EVALUATION OF FOOT-TRANSMITTED VIBRATION AND TRANSMISSIBILITY CHARACTERISTICS OF MINING BOOTS AND INSOLES

byPULKIT SINGH

Thesis submitted in partial fulfillment of the requirements for the degree of Master of Human Kinetics (MHK)

School of Graduate Studies Laurentian University

Sudbury, Ontario

©PULKIT SINGH, 2013

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Abstract

Vibration can enter the body of mobile equipment operators, the hands of workers using

power-tools or the feet of workers standing on vibrating platforms (Eger et al, 2006).

Epidemiologically, 4-7% of workers in Canada, the United States and the European

Union are exposed to potentially harmful vibrations (Bovenzi, 1996). Mine workers

drilling from stationary platforms are exposed to whole-body vibration above the eight

hour health guidance caution zone set-out in ISO 2631-1 (Leduc et al, 2010). Literature

suggests that the health effects typically observed in the hands have been reproduced in

the feet when exposed to similar vibration frequencies and accelerations (Griffin, 2008).

However, research associated with foot transmitted vibration (FTV) is limited despite

evidence of negative health effects of vibration at the foot, either with direct segmental

exposure (Thompson et al, 2010) or indirectly with hand-arm vibration exposure

(Sakakibara and Yamada, 1995). Improved understanding of FTV is warranted, to deal

with potentially harmful vibrations, which lead to injury, and to identify interventions

capable of attenuating harmful vibrations at the foot.

The primary objective of study one (Chapter 2) was to determine the vibration

transmissibility between the floor and the ankle when exposed to FTV. The

transmissibility between the floor and ankle was compared between males and females

and between different foot arch types to determine if there was a significant difference in

floor-to-ankle vibration transmissibility. The second objective was to determine if there is

correlation between floor-to-ankle transmissibility and participant reported discomfort

scores. Sixteen university aged participants (eight males and eight females) participated in

the study. The participants were exposed to two levels of vibration, while standing on a

low frequency (3.15-lOHz) and a high frequency (40Hz) vibration platform. Vibration

was recorded at the floor and the ankle with two tri-axial accelerometers in accordance

with the ISO 2631-1 guidelines. Participants reported body discomfort on a 9-point

discomfort scale following each vibration trial. Vibration recorded in the z-axis (vertical

axis) entering the foot (Fawz) was compared to vibration recorded in the z-axis at the

ankle (Aawz). The percentage difference between Aawz and Fawz was taken as a measure

of vibration transmissibility from the floor through the foot to the ankle. There was a

significant difference in floor-to-ankle vibration transmissibility (p= 0.001; F= 3.27) by

vibration exposure frequency. The participants attenuated FTV when exposed to high

frequency vibration; however, there was no significant attenuation of vibration during low

frequency vibration exposure. There was no significant difference in the floor-to-ankle

vibration transmissibility or discomfort by gender (p= 0.715), or foot arch type (p=

0.515).

Despite evidence to support their efficacy, many industries use mats and insoles believing

they are capable of attenuating FTV (Leduc et al, 2011). Therefore, the primary objective

of the second study (Chapter 3) was to determine the transmissibility of commercially

available insoles and mining boots. Sixteen participants (eight males and eight females)

experienced four insoles and two mining boot conditions at two vibration levels, while

standing on a low frequency vibration platform (3.15-10Hz) and a high frequency

vibration platform (40Hz). Vibration was recorded at the floor and above the insole/boot

at the ankle with two tri-axial accelerometers in accordance with the ISO 2631-1

standard. The percentage difference between the vibration recorded at the ankle (Aawz)

and the vibration recorded at the floor (Fawz) was used to determine vibration

transmissibility of the insole/mining boot. A paired comparison of the insoles/mining

boots was also done to identify the preferred insole/mining boot based on participant

comfort reports (9-point scale) provided after each insole/mining boot condition. There

was a significant difference in vibration transmitted from the floor through the insole (p=

0.00; F= 17.91) and boot (p= 0.014; F= 6.31) to the ankle by exposure frequency. All the

insoles and mining boots attenuated vibration during high frequency vibration exposure;

however, with the exception of mining boot 1 none of the insoles or mining boot 2 were

effective in attenuating vibration during low frequency FTV. There was no significant

difference in vibration transmissibility or reported discomfort between genders. The

participants identified insole-3 and mining boot-2 as most comfortable when exposed to

low frequency and high frequency FTV. Future studies should identify an effective boot-

insole combination capable of attenuating vibration frequencies believed to contribute to

potential health risks at the feet.

VI

Acknowledgement

“I can no other answer make, but, thanks, and thanks” - William Shakespeare

Finally I am taking this privilege to thank all the wonderful people who helped me from

the beginning to the completion of this project. Believe me it wouldn’t have been such a

smooth and pleasant journey without having all of you around. Every one of you fills a

space of deep respect in my heart.

I am very thankful to my family for providing me this great opportunity while staying

away from everyone. At last, I followed the tradition of success and your belief and love

was always a source of inspiration whenever I was down. Thank you Papa, Mummy and

Bhai, I love you all.

Especially I would like to thank my mentor, Dr. Tammy Eger who always stood by me

throughout the project and for being a great source of inspiration. Tammy, the way you

managed all the situations and your brilliant ideas were key to the successful completion

of the project. In one word, you are the best and I feel fortunate to have worked under

your supervision. Thank you Dr. Eger.

I would also like to thank Dr. Sylvain Grenier and Dr. Alison Godwin. It was impossible

to complete the project without your valuable time and suggestions. Thanks to Dr.

Michelle Oliver, Dr. Jim Dickey and Dr. Ron House for their collaboration and valuable

input to the project.

VII

Thanks to Sulabh Singh, Mallorie Leduc, Ashish Dhall, Jason Chevrier and Matthew

Felton for helping me in the data collection and with my pilot studies.

I would like to acknowledge the continuous help and support from the Centre for

Research Expertise in the Prevention of Musculoskeletal Disorders, Workplace Safety

and Insurance Board of Ontario, Ontario Mining Industry and Workplace Safety North

for financially supporting the project.

At last, my deepest gratitude to all the participants who voluntarily stepped on the

vibration platform for this project.

Thank you everyone.

VIII

Co-Authorship and Author Contributions

Chapters 2 and 3 have been presented as draft manuscripts intended for submission to a

peer-review journal.

Chapter 2:

EVALUATION OF GENDER DIFFERENCES AND FOOT ARCH TYPE IN FOOT TRANSMITTED VIBRATION

Chapter 3:

EVALUATION OF VIBRATION TRANSMISSIBILITY PROPERTIES AND COMFORT OF INSOLES AND BOOTS WORN BY MINE WORKERS

The research work completed in Chapter 2 and Chapter 3 was financially supported by

the Workplace Safety and Insurance Board of Ontario and the Centre of Research

Expertise for the Prevention of Musculoskeletal Disorders (CRE-MSD). The Ontario

mining industry and Workplace Safety North also provided continued support for the

research work.

IX

TABLE OF CONTENTS

1. Review of Literature 1

1.1 Introduction 2

1.2 Understanding Vibration 4

1.3 Epidemiology and Health Effects 5

1.4 Hand-Arm Vibration Exposure 9

1.5 Whole-Body Vibration Exposure 14

1.6 Effect of Vibration in Standing 15

1.7 Biodynamic Response and Transmissibility 19

1.8 Comparison Between Hand-Arm and Foot-Ankle Response to Vibration 23

1.8.1 Anatomy of Hand and Foot 23

1.8.2 Arches of the Foot 24

1.8.3 Assessment of the Foot Arch 25

1.8.4 Bio-dynamics and Vibration Transmissibility of the Hand 26

1.9 Strategies to Reduce Vibration 29

1.9.1 Reduction Strategies for WBV Exposure 29

1.9.2 Reduction Strategies for HAV Exposure 31

1.9.3 Reduction Strategies for FTV Exposure 33

1.10 Thesis Outline 33

References 36

X

2. Examination of Floor to Ankle Vibration Transmissibility and Subjective Discomfort of Males and Females with Different Foot Arch Classification when Exposed to Foot Transmitted Vibration

Abstract

2.1 Introduction

2.2 Methodology

2.2.1 Participants

2.2.2 Vibration Exposure

2.2.3 Vibration Measurement

2.2.3.1 Vibration Measurement at Platform

2.2.3.2 Vibration Measurement at Ankle

2.2.4 Foot Arch Assessment

2.2.5 Discomfort Measurement

2.2.6 Floor to Ankle Vibration Transmissibility Measurement

2.2.7 Data Collection Procedure

2.2.8 Data Analysis

2.2.9 Statistical Analysis

2.3 Results

2.3.1 Floor to Ankle Vibration

2.3.2 Discomfort Score

2.4 Discussion

2.4. ITransmissibility

2.4.2 Discomfort

2.5 Limitations

2.6 Conclusion

References

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XI

3. Evaluation of Vibration Transmissibility Property and Comfort of Insoles and Boots Worn by Mine Workers

Abstract

3.1 Introduction

3.2 Methodology

3.2.1 Participants

3.2.2 Insoles and Boots Evaluated

3.2.3 Vibration Exposure

3.2.4 Vibration Measurement

3.2.4.1 Vibration Recording at Floor

3.2.4.2Vibration Recording at Ankle

3.2.5 Transmissibility Measurement

3.2.5.1 Effective Amplitude Transmissibility of Insoles and Boots

3.2.6 Discomfort Score

3.2.7 Paired Comparisons

3.2.8 Data Analysis

3.2.9 Statistical Analysis

3.3 Results

3.3.1 Insole Transmissibility

3.3.2 Discomfort Score Associated with Insole Transmissibility

3.3.3 Mining Boot Transmissibility

3.3.4 Discomfort Score Associated with Boots

3.4 Discussion

3.4.1 Transmissibility

3.4.2 Discomfort

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XII

3.5 Limitations 124

3.6 Conclusion 125

Reference 126

4. General Discussion 134

4.1 Linking of the Previous Chapters 134

4.2 Relevance to the Mining Industry 135

4.3 Relevance to the Medical Industry 135

4.4 Relevance to the Insoles/Mining Boot manufacturing Industries 136

4.5 Conclusion 136

References 138

Appendix 1 141

Appendix 2 147

Appendix 3 153

Appendix 4 159

Appendix 5 168

Appendix 6 174

Appendix 7 207

XIII

List of Figures

Chapter 1

1.1 Pictorial Demonstration of Arches of Foot 25

Chapter 2

2.1 Placement of Accelerometers 60

2.2 Accelerometer placed on lateral malleolus of the ankle and secured by taping 61

2.3 Foot Print for Measurement of Arch Index 63

2.4 Axis Orientation of the Ankle Accelerometer 66

2.5 Main Effect Plot for the Percentage Vibration Transmissibility Versus Gender, Frequency and Mass

2.6 Interaction Plot for the Percentage Vibration Transmissibility Versus Gender, Frequency and Mass

Chapter 3

3.1 The Commercially Available Insoles Tested

3.2 Two Types of Commercially Available Mining Boots that were Tested

3.3 Accelerometer Mounted Over the Lateral Malleolus of the Left Ankle Above the Cut off Boot

3.4 Placement of Accelerometers

3.5 Axis Orientation of the Ankle Accelerometer

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3.6 Accelerometer Placed on the Lateral Malleolus of the Ankle and Secured by Pro-Wrap Taping 106

3.7 Main Effect Plots for the Percentage Vibration Transmissibility Versus Gender, Frequency, Insole and Mass

3.8 Interaction Plot for the Percentage Vibration Transmissibility Versus jjj Gender, Frequency, Insole and Mass

3.9 Main Effect Plots for LB Discomfort Versus Gender, Frequency, Insole and Mass 114

XIV

3.10 Main Effect Plots for UB Discomfort Versus Gender, Frequency, Insole and Mass

3.11 Main Effect Plots for the Percentage Vibration Transmissibility Versus Gender, Frequency, Boots and Mass

3.13 Main Effect Plots for UB Discomfort Versus Gender, Frequency, Boot and Mass

3.14 Main Effect Plots for LB Discomfort Versus Gender, Frequency, Boots and Mass

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3.12 Interaction Plot for the Percentage Vibration Transmissibility Versus Gender, Frequency, Boots and Mass 119

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XV

List of Tables

Chapter 1

1.1 Different Body Areas and there Reported Resonant Frequency Range 7

1.2 Reported Cases with Raynaud’s Phenomenon of Toes in Vibration Exposed 17 Workers

Chapter 2

2.1 Demographic Data and Pre-test Discomfort Rating

2.2 Summary of the Vibration Characteristics

2.3 Multivariate Analysis: GLM ANOVA Transmissibility Versus Gender, Frequency,Mass, Discomfort and Foot Arch Type

3.2 Paired Insole Comparisons for Vibration Testing

3.3 Paired Boot Comparisons for Vibration Testing

3.4 Multivariate Analysis: GLM ANOVA Transmissibility Versus Gender, Frequency, Insole, Mass and Discomfort

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59

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2.4 Mean Vibration Transmissibility in the Males and Females with Different Foot Arch Types at LF and HF Vibration Exposure ^

Chapter 3

3.1 Demographic Data and Pre-test Whole Body Musculoskeletal Discomfort Reported by the Participants on a Nine Point Scale

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3.5 Transmissibility and Discomfort Score During Three Different Insole Condition in 110 Males following HF and LF Vibration Exposure

1123.6 Transmissibility and Discomfort Score During Three Different Insole Condition in Females following HF and LF Vibration Exposure

3.7 Transmissibility and Discomfort Score for Boot Conditions in Males following HF and LF Vibration Exposure

3.8 Transmissibility and Discomfort Score for Boot Conditions in Females following HF and LF Vibration Exposure

1173.9 Multivariate Analysis: GLM ANOVA-Transmissibility Versus Gender, Frequency,Boots, Mass and Discomfort 118

Glossary

XVI

Abbreviation Long FormA(8) 8-hour energy equivalent vibration total valueANOVA analysis of variance&wx frequency-weighted r.m.s. acceleration in the x-axis

frequency-weighted r.m.s. acceleration in the y-axisaWz frequency-weighted r.m.s. acceleration in the z-axisDF dominant frequencyFTV foot-transmitted-vibrationHAV hand arm vibrationHAVS hand arm vibration syndromeHGCZ health guidance caution zone

HF high frequencyISO International Organization for StandardizationIN 1 insole 1IN 2 insole 2IN 3 insole 3LB lower bodyLF low frequencyNIN no insoler.m.s. root-mean-squareSD standard deviationUB upper bodyVATS vibration analysis tool-setVDV vibration dose valueVWF vibration white fingerVWFt vibration white footWBV whole-body vibrationwd weighting factor, applied to the x & y axes, as described in ISO 2631-1Wk weighting factor, applied to the z-axis, as described in ISO 2631-1

XVII

Vibration Terminology and Definitions

Listed below are the vibration related terms, along with a basic definition, that have been

used throughout the thesis document. However, for a detailed understanding of

terminologies related to mechanical vibration and shock, the reader should refer to the

1997, ISO 5805 (mechanical vibration and shock - human exposure - vocabulary)

document and the 1990, ISO 2041 (vibration and shock - vocabulary) document.

,4(8) - The 8-hour energy equivalent vibration total value for a worker in meters per

second squared (m/s2), including all whole-body vibration exposures during the day.

Acceleration: A vector quantity that specifies the time-derivative of velocity.

Accelerometer: A pick-up that converts an input acceleration to an output (usually

electrical) that is proportional to the input acceleration.

Amplitude: The maximum value of a sinusoidal vibration.

Amplification: A signal is said to be amplified if it increases in amplitude and intensity

Attenuation: Attenuation is the reduction in amplitude and intensity of a signal. For

example, a vibration signal may be attenuated as it is transmitted through the body.

Biodynamics: The science of the physical, biological and mechanical properties and

responses of the human body (tissues, organs, parts and systems) to an external force

(vibration) or in relation to the internal forces, produced by an interplay of external forces

and the body’s mechanical activity.

Comfort: Subjective state of well-being or absence o f mechanical disturbance in relation

to the induced environment (mechanical vibration or repetitive shock).

XVIII

Damping: The dissipation of energy with time or distance (i.e. the amplitude of the

vibration signal decreases).

Directional vibration: Translational or rotational mechanical vibration [shock] acting

upon a human as a whole or upon parts of a human (e.g. hand, head or limbs).

Dominant frequency: A frequency at which a maximum value occurs in a spectral

density curve.

Frequency weighted: A term indicating that a wave-form has been modified according

to some defined frequency weighting.

Frequency weighting: A transfer function used to modify a signal according to a

required dependence on vibration frequency. For whole-body vibration, the frequencies

thought to be most important range from 0.5-80Hz. However, because the risk of damage

to different body parts is not equal at all frequencies a frequency weighting is used to

represent the likelihood of damage from the different frequencies.

Hand arm vibration/hand transmitted vibration: Mechanical vibration directly applied

or transmitted to the hand-arm system, commonly through the palm of the hand or

through the fingers gripping a tool or work piece.

ISO 5349-1: The International Standard for the measurement and assessment of human

exposure to hand-transmitted vibration.

ISO 2631-1: The International Standard used to describe the effects of whole body

vibration exposure on human health.

Peak value: The maximum value of a vibration (maximum deviation from the mean

value) during a given interval.

XIX

Resonance: A resonance of a system in forced oscillation exists when any change,

however small, in the frequency of excitation, causes a decrease in a response of the

system.

Resonant frequency: The frequency at which resonance occurs. At the resonant

frequency of a system, peak oscillation will occur.

r.m.s. value: For a set of numbers, the square root of the average of their squared values.

Shock absorber: A device for the dissipation of energy in order to reduce the response of

a mechanical system to applied shock.

Segmental vibration: Mechanical vibration applied or transmitted to a particular

segment, area or region of the human body.

Transmissibility: The unit-less ratio of the response amplitude of a system, in steady-

state forced vibration, to the excitation amplitude. A value greater than one would

indicate the vibration was amplified as it travelled from the “input location” to the

“output” locations, whereas a value less than one would indicate attenuation.

Transfer function: A mathematical relationship between the output and the input of the

system.

Transient vibration: The vibratory motion of a system other than steady-state or

random.

Vibration: The variation with time of the magnitude of a quantity which is descriptive of

the motion or position of a mechanical system, when the magnitude is alternately greater

and smaller than some average value or reference.

XX

Weighted acceleration: Weighted vibration level value or set of values of vibrational or

repetitive shock acceleration affecting human that has been subjected to a computational

or signal conditioning operation to reflect human response characteristics as a function of

vibration frequency or exposure time.

VATS: The Vibration Analysis Toolkit. A software application used to derive the

various measures required by the ISO 2631-1 standard for assessing the health effects of

whole-body vibration exposure.

Whole Body Vibration: Mechanical vibration transmitted to the body as a whole,

usually through areas of the body (e.g. buttocks, soles of the feet, back) in contact with a

supporting contact surface that is vibrating.

x-axis vibration: Translational mechanical vibration in the direction of the x-axis of the

anatomical coordinate system of the human body or of a part of the body.

y-axis vibration: Translational mechanical vibration in the direction of the y-axis of the

anatomical coordinate system of the human body or of a part of the body.

z-axis vibration: Translational mechanical vibration in the direction of the z-axis of the

anatomical coordinate system of the human body or of a part of the body.

CHAPTER 1

REVIEW OF LITERATURE

1.1 Introduction

People can be exposed to vibration in the workplace and/or during activities of their daily

life. Automobiles, different equipment and industrial activities expose people to periodic,

random and transient mechanical vibration, which can interfere with comfort, activities

and health (ISO 2631-1, 1997). In the workplace, people can be exposed to vibration

when standing, sitting, and in some cases, when lying while in contact with a vibration

source. Vibration exposure has been one of the latent causes for occupational health

injury/disease in many industries. The harmful effects of vibration on health usually

appear after several years of vibration exposure (Fritz, 2000). Knowledge of how

vibration is transmitted to and through the human body can provide an important input to

our understanding of the bio-dynamic response of the body to vibration exposure. Also an

improved understanding of vibration transmissibility is also necessary for proper design

and application of protective measures to attenuate harmful vibrations.

The International Organization for Standardization (ISO) provides guidelines for

vibration exposure and measurement in ISO 2631-1: Mechanical vibration and shock -

Evaluation of human exposure to whole-body vibration - Part 1: General requirements.

The guidelines are applicable to situations where the individual is exposed to whole-body

vibration when sitting, standing, or lying on a vibrating surface. Similarly, The ISO

provides further guidelines for measuring segmental vibration transmitted through the

hand-arm system; ISO 5349-1: Mechanical vibration - Guidelines for the measurement

and the assessment of human exposure to hand-transmitted vibration. However, an

analogous standard to assess health risks associated with segmental vibration transmitted

through the feet does not exist. Currently, exposure to foot-transmitted vibration (FTV),

3

whether of a whole-body or segmental nature, is evaluated according to ISO-2631-1

guidelines. Recent work by Leduc et al. (2011) and Thompson et al. (2010) suggests this

may not be the best approach.

Exposure to whole-body vibration (WBV) from a seated position and techniques to

attenuate vibration that enters the body when seated has been widely studied (Paddan et

al, 2001; Niekerk et al, 2003). Similarly hand arm vibration (HAV) exposure associated

with gripping tools that vibrate rapidly has been studied in more depth (ISO 5349-1,

1986) and attention is turning to the development of anti-vibration tools and gloves to

reduce HAV exposure (Jetzer et al, 2003). However, health effects associated with

exposure to FTV and the bio-dynamic response of the feet to FTV are less understood.

Workers can be exposed directly or indirectly to FTV. For example, indirect exposure can

occur from hand-held drills attached to the standing platform (Hirata et al, 2004; Leduc et

al, 2011). On the other hand, direct vibration exposure occurs when the workers stand to

operate mobile equipment such as locomotives (Eger et al, 2006; Leduc et al, 2011).

Exposure to FTV can affect neurological, vascular and musculoskeletal systems of the

exposed worker, which occurs either due to direct exposure or as a secondary

complication to HAV syndrome (Sakakibara, 1995). Despite evidence of negative health

effects associated with FTV, little is known about the bio-dynamic response of the feet

and lower body to vibration. Even though awareness to prevent health hazards associated

with FTV has been employed by many industries with the use of anti-vibration mats,

insoles and mining boots, the efficacy of these materials in reducing vibration

transmissibility is yet to be proved.

In the following sections, vibration will be discussed in general terms and

epidemiological evidence for health effects associated with WBV, HAV and FTV will be

presented. The importance of an improved understanding of the structures exposed to

vibration will also be discussed before attention is given to interventions aimed at

decreasing the health risks associated with exposure to vibration. Lastly, the objectives of

the research project will be outlined.

1.2 Understanding Vibration

Vibration is a mechanical movement that oscillates about a fixed (often a reference) point.

Oscillatory displacement involves alternating velocity in one direction with a velocity in

the opposite direction. This change of velocity means that the object is constantly

accelerating, first in one direction and then in the opposite direction (Griffin, 1998). The

oscillations produced are characterized as a simple harmonic sine wave or a multiple

wave complex differing in frequency and acceleration, or a random non-repeating series

of complex waves (Palmear, 1998). Vibration needs a medium to propagate the energy

through a system (Mansfield, 2005). When an individual is exposed to vibration, the

vibration energy is transmitted into the body through compressions and rarefactions of

tissues and fluids in the body (wave-propagation).

In order to describe the characteristics of a vibration signal, frequency and acceleration

are generally reported. Acceleration is a measure of the magnitude or amplitude of signal

oscillation and is typically reported in m/s2 (meters per second squared). Frequency is a

measure of the number of oscillatory motions completed in one second and is measured in

cycles/second or Hertz (Hz). Vibration can occur along three principal axes: vertical

vibrations are measured along the z-axis, fore-aft vibrations are measured along the x-

axis, and side-side (lateral) vibrations are measured along the y-axis.

1.3 Epidemiology and Health Effects

International Labor Office in 1977 identified vibration exposure as being one of the latent

causes for occupational injury/disease in many industries (Mandal, 2006). Studies have

reported that approximately 4-7% of workers in Canada, the United States and European

countries are exposed to vibration that may potentially cause negative health effects

(Bovenzi, 1998; Bernard, 1997). In 2006, Mandal reported increased HAV/WBV injury

risk to Indian workers in mines due to vibration exposure. In South Africa gold mines, the

prevalence rate of HAVS is estimated at 15% of the mine workers exposed to vibration

(Dias et al, 2005-cited in Mandal, B. B. (2006). Risk from vibration in Indian mines.

Indian Journal of Occupational and Environmental Medicine, 10(2), 53).

Long-term vibration exposure on a regular basis can cause vascular, musculoskeletal and

neural disorders (Sakakibara, 1994; Abercromby et al, 2007). Human response to

vibration depends on the part of the body that is exposed, the dominant frequency and the

amplitude of the vibration exposure. Vibration can be transmitted to the whole body

(whole-body vibration or WBV) through a supporting surface, for example, the feet of a

standing person or the buttocks of a seated person, or exposure can be more localized

(segmental vibration), as in the case of vibration experienced at the hand-arm system

(HAY) or foot-transmitted vibration (FTV). In 1911, Giovanni Loriga of Italy first

6

reported HA VS among stone-cutters using pneumatic hammers on marble and stone

blocks (Griffin, 1998). They suffered from autonomic neurovascular disease of the hand

and fingers as described by Maurice Raynaud in 1862. Thereafter, many researchers

discovered the adverse health effects of vibration and several studies were carried out

with an aim to reduce occupational vibration exposure and vibration related health

disorders.

The risks involved with vibration exposure are greatest when the vibration magnitudes are

high, the exposure durations long, frequent and regular, and the vibration includes severe

shocks or jolts. Major musculoskeletal health effects reported from WBV exposure

include lumbago, early degenerative changes of the vertebrae and intervertebral disc

herniations (Mayton et al, 2008; Slota et al, 2007; Pope et al, 1998). In 1986, Seidel and

Heide reported that WBV may also contribute to the development of noise induced

hearing loss (Seidel and Heide, 1986).

Similarly, workers exposed to HAV have reported symptoms of neurovascular changes in

their fingers and hand which include blanching of the fingers; tingling, numbness and

reduced thermal and tactile sensations of the fingers and hands; and a reduction in

muscular strength and dexterity (European Union, 2006; Cohen et al, 1995; Bovenzi,

1998). However, the human response is complicated by the fact that the body does not

respond equally to all frequencies (Table 1.1). Each segment or component of the human

body has its own critical frequency at which it oscillates to its maximum amplitude and

hence producing maximum shear forces in the body tissue. This typical frequency is

identified as the resonant frequency (Table 1.1) of the exposed body segment and is

closely related to WBV exposure frequency (1-20 Hz) (Holmlund et al, 2001).

7

Table 1.1: Different body areas and their reported resonant frequency range

Body Parts Resonant

Frequency

(as reported)

Reference

Eye balls 20-25 Hz Mandal et al. (2006)

Knee 4-8 Hz

Abdomen 4-8 Hz

Chest 4-8 Hz

Skull (sitting/reclining) 50-70 Hz

Hand-arm 20-50 Hz Dong et al. (2004)

Fingers >80 Hz Dong et al. (2010);

Lundstrom (1984)

Spine 5 Hz Mandal et al. (2006)

Feet currently not known

For instance, it has been shown that the spine has a resonant frequency of about 5 Hz

(Griffin, 1990; Dupuis et al, 1986), a frequency produced when operating industrial

mobile machinery and earth moving machinery (Christ et al, 1989). Thus, this could be a

reason for back pain in many professional drivers (Bovenzi et al, 1999). However,

frequencies in the range of 20-50 Hz are considered potentially damaging to the hand-arm

system (Dong et al, 2004) and frequencies above 80 Hz for the fingers (Dong et al, 2010).

8

In 2010, Krajnack et al, in a study done on a rat-tail, reported that the greatest vibration

transmissibility was recorded at 250 Hz. This is an important finding from HAV point of

view since the physiological effects of vibration on the human finger has been shown to

behave in a similar fashion (due to a similar anatomical make up and orientation of

capillaries) to a rat tail exposed to vibration (Krajnack et al, 2010).

Vibration exposure when standing, and the resulting health effects to the feet, have

received little attention and the impact of vibration frequency on the feet is not

understood. However, it has been reported that there is a greater transmission of vertical

vibration to the pelvis and lower spine in the standing posture than in the sitting posture

(Matsumoto and Griffin, 2000). Neurological symptoms typically observed in the hands

after occupational exposure to HAV have been reproduced in the feet when exposed to

similar vibration frequencies and accelerations (Griffin, 2008). Furthermore, long-term

exposure to FTV has been linked with vibration-induced white toes in the feet of workers

(Sakakibara, 1994; Thompson et al, 2010). Vibration exposure via the feet has also been

found to cause muscle and nerve fibre degeneration in animal models (Shanskaya et al,

1967 and Lundborg et al, 1990). Considering the similar anatomical architecture of the

hands and feet (except the bone and muscle size and mass), the physiological response of

the feet to vibration exposure could be expected to be in line with the vibration exposure

response of the hands. Some research studies have shown similar pathophysiological

findings in the feet and also a correlation between vibration syndrome of the hands and

the feet (Sakakibara, 1995; House et al, 2011). In another study by Thompson et al, the

authors observed vibration-white-feet (VWFt) solely from exposure to FTV, i.e.

independent of exposure to HAV (Thompson et al, 2010). Based on current and past

findings, further research is warranted to better understand the injury mechanism of foot

transmitted vibration.

1.4 Hand Arm Vibration Exposure

‘The mechanical vibration that, when transmitted to the human hand-arm system, entails

risks to the health and safety of workers, in particular vascular, bone or joint, neurological

or muscular disorders is known as hand arm vibration’ (Directive 2002/44/EC of the

European Parliament). Hand Arm vibration is caused by vibration transmitted into the

hand and arms through the palm and fingers. The handle of the machine or the surface of

a work piece vibrates rapidly and this motion is transmitted into the hand and arm holding

the equipment. The development of HAVS depends on various factors as identified by

Wang et al, which include the vibration magnitude of the tool, the volume of cumulative

exposure and the ergonomics (grip, posture, adjustability) o f the tool in use (Wang et al,

2005). Frequencies ranging from 2 to 1500 Hz have been reported to be potentially

damaging (Patient UK). However Dong et al, have identified that frequencies ranging

from 20-50 Hz range produces significant damage to the Hand-Arm system and

frequencies above 80 Hz are reportedly more damaging for the fingers (Dong et al, 2004;

Dong et al, 2010).

“Palmear and Wasserman summarized the clinical symptoms o f HAV (Palmear, 1998)

as

a. Tingling and/or numbness in the finger(s) initially - similar to but not the same as

Carpel Tunnel Syndrome (CTS)

b. As the exposure continues, the appearance of a single white or blanched fingertip

occurs - usually, but not always in the presence of cold. It is called Vibration

10

Induced White Fingers (VWF) and the condition is known as Hand Arm Vibration

Syndrome (HAVS).

c. With further exposure, these attacks increase in number, intensity and duration,

especially in cold conditions.

d. In extreme and rare cases, the loss of blood supply to the fingers can lead to

gangrene, which may require amputation.

Workers whose hands and fingers are regularly exposed to hand arm vibration have been

reported to suffer from various musculoskeletal and soft tissue disorders of the hands and

arms, e.g. Dupuytren’s (Liss et al, 1996 and Thomas et al, 1992).

The workers with long-term and regular vibration exposure have reported changes in their

tactile and thermal sensations, and reduced hand function with precision and prehension

activities with loss of dexterity. HAV has also been reported to cause muscular weakness,

pain in the hands and arms, wrist and elbow osteoarthritis, hardening (ossification) of soft

tissues, carpal tunnel syndrome and tendinitis (EU Guide to good practice on HAV,

2006).

When assessing a worker for adverse exposure to HAV, vibration exposure magnitude is

expressed in terms of the frequency-weighted acceleration of the surface of the tool-

handle or work-piece that is in contact with the hand. The Vibration Directive (Directive

2002/44/EC) of European Union sets a daily exposure action value of 2.5m/s2 and a daily

exposure limit value of 5m/s2 to control HAV-associated risks. The International

Organization for Standardization provides further guidelines applied solely to hand-arm

vibration exposure; ISO 5349-1: Mechanical vibration - Guidelines for the measurement

and the assessment of human exposure to hand-transmitted vibration. According to the

11

standard, symptoms of hands-transmitted vibration are rare for a vibration total

acceleration value less than 2 m/s2.

Through the autonomic nervous system changes, HAV is also believed to affect the feet

of workers (even if the feet have not been in direct contact with a vibrating surface). The

HAV exposure has been reported to induce vasoconstrictive changes in the periphery

through activation of sympathetic channels of the autonomic nervous system. Thus,

individuals with HAVS also experience circulatory disturbances in their feet (Sakakibara

et al, 1995). Studies have shown that acute vibration exposure to one hand is associated

with vasoconstriction in not just the exposed hand but also the contralateral hand

(Farkkila et al, 1978; Egan et al, 1996; Bovenzi et al, 1995) and the toes of the foot (Egan

et al, 1996; Sakakibara et al, 1990). Further, it was reported that the central sympathetic

vasoconstrictor reflex is responsible for vibration induced vasospasm in the extremities

(Olsen et al, 1993) and that this reflex is increased in case of HAVS (Greenstein et al,

1992). The changes in the peripheral nervous system in the upper extremities have been

conventionally considered to be a direct effect of segmental HAV exposure. In a study by

Hirata et al. in 1995, 59 patients with HAVS and 49 controls were examined for their

sural and medial plantar sensory nerve conduction velocity. A reduction in medial plantar

nerve conduction velocity was reported in the patients with HAVS. However, the

reduction of sensory nerve conduction velocity of the medial plantar nerve in HAVS

patients is considered to be an indirect effect of vibration exposure in the feet because of

its distant location from the vibration exposed hands in HAVS patients (Hirata et al,

1995). Researchers suggested vasoconstrictive changes due to sympathetic stimulation in

HAVS patients as a cause of the reduction in the sensory nerve conduction velocity in the

foot. The structural changes in the localized neural tissue following long-term vibration

12

exposure have also been reported in the past. In a study by Takeuchi et al. increased

number of Schwann cells and fibroblasts with strong collagen formation, severe loss of

myelin sheath and perineural fibrosis in the neural tissues were reported from a

pathological study of 60 fingers from 30 patients with HAVS (Takeuchi et al, 1986). The

reduction in the nerve conduction velocity could also be the result of demyelination and

structural changes in the perineural tissues as reported.

Patients with HAVS have been reported to experience a decrease in the temperature of

their feet as well as the hands and have low skin temperature of the fingers and toes

following cold exposure (Sakakibara et al, 1991; Hirata et al, 1995). In a study by

Sakakibara; 11 subjects with VWF, 12 subjects without VWF (but exposed to vibration

by hand) and 20 healthy individuals were exposed to 3 minutes of immersion of the foot

in cold water at 10 degree Celsius. It was found that the group with VWF showed the

lowest skin temperature of both the upper and lower extremity. Thus, it was reported by

the authors that patients with HAVS, especially those with VWF, have circulatory

disturbances in the foot as well as in the hand. Furthermore, skin temperature studies of

the hands and feet of patients with HAVS showed a positive correlation with symptoms

(Sakakibara et al, 1991).

Due to long-term vibration exposure, localized structural changes have also been

observed in the peripheral vasculature of patients with VWF. Thickening of the tunica

media of the arterial wall in the hands and fingers was reported in patients with VWF

(Sakakibara et al, 1995). In another study by Hashiguchi et al. (1994), fingers and toes

from 21 males with HAVS and 13 referent male cadavers showed structural changes in

the hand and foot vasculature. The study reported thickening of the tunica media and

increased collagen fibres in the perivascular regions of both the fingers and the toes of

patients with HAVS (Hashiguchi et al, 1994). The impact o f the localized effects of the

vibration exposure has been depicted by the finding that the ratio of the diameters of the

tunica media to tunica externa was higher in the patients directly exposed to FTV than

those who were not exposed to foot vibration directly but presented with HAVS

(Hashiguchi et al, 1994). Although there seems to be a positive correlation between

HAVS and observed pathophysiological changes in the lower extremity (though indirect),

which leads to vibration symptoms in the feet of workers exposed to vibration via feet,

the findings also suggests direct effects of the vibration exposure in the feet. However, the

structural changes in the foot vascular and perivascular structures could also result from

long-term HAV exposure due to the repeated sympathetic stimulation leading to

vasoconstriction of the extremity vessels (Hashiguchi et al, 1994). Thompson et al. (2010)

reported a case study documenting the direct effect of segmental vibration exposure in the

feet. The case report shows that a condition analogous to HAVS might occur in the feet

after prolonged exposure to segmental lower-extremity vibration in workers. The results

showed a vasomotor disturbance associated with cold sensitivity in the toes but not in the

hands of the miner who was exposed to vibration from underground bolting machines for

18 years (Thompson et al, 2010). Most researchers prior to 2010 have related the

vascular symptoms in the feet of HAVS patients to be primarily due to a centrally

mediated sympathetic mechanism. But for the first time, this case suggests that while

centrally mediated mechanisms may contribute to the vibration syndrome in the hands

and feet, the direct segmental vibration exposure also plays a significant role in the

structural changes of the exposed body segment. However, further research is required to

provide additional evidence to substantiate this new finding.

14

1.5 Whole Body Vibration Exposure

Whole Body Vibration (WBV) is a mechanical vibration that, when transmitted to the

whole body, increases the risk to the health and safety o f workers, in particular lower

back morbidity and trauma of the spine (Directive 2002/44/EC of the European

Parliament). Exposure to WBV is encountered in various areas such as farming,

construction, mining and quarrying, truck drivers, motor boats and helicopters. WBV

exposure can occur while sitting, standing or lying in contact with the vibration source

(ISO 2631-1; 1997).

WBV has repeatedly been identified as a risk factor for low back pain (Bernard, 1997;

Bovenzi, 1992, 1994, 1999; Lis et al, 2007 and Seidel, 2005). Prolonged WBV exposure

may cause mechanical damage to the spine, vertebral end plates, intervertebral discs and

low back musculature thereby causing lumbago (Wikstrom et al, 1994). According to

Panjabi (1992) any impairment in the passive, active or neural subsystems of the spine

may lead to lumbar spine instability and associated tissue damage. Muscles representing

Panjabi’s lumbar-stability hypothesis are influenced by vibration. Tonic lumbar reflex

(TLR) occurs in the back muscles at frequencies between 1 and 5 Hz (Seidel, 1988).

WBV also causes impairment in postural control of the trunk which implies impairment

in spinal stability and a mechanism by which vibration exposure may increase low back

injury risk (Slota et al, 2007). Other associated systemic disorders due to WBV exposure

includes varicose veins, menstrual disorders, proneness to abortion and hyperemesis

gravidum in women exposed to WBV (Abrams, 1990; Wasserman et al, 1997); increase

in blood volume during the phases of ovulation and menstruation (Abrams, 1990;

Wasserman et al, 1997); digestive system disorders (Seidel H, 1986); frequencies below

15

20Hz affects cardiovascular system and results in hyperventilation, increase in heart rate,

oxygen intake and respiratory rate (Griffin, 1998); headaches, sleep disturbances,

increased irritability and impotence has also been reported following WBV exposure

(Dupuis et al, 1985). WBV is also known to affect the vestibular system (Roll et al, 1980;

Gauthier et al, 1981) and visual systems (Ishitake et al, 1998).

The European Union Vibration Directive (Directive 2002/44/EC) sets a daily vibration

exposure action value of 0.5m/s and a daily vibration exposure limit value of 1.15m/s to

control the WBV risks among workers. The International Organization for

Standardization (ISO) also provides guidelines for vibration exposure and measurement

in ISO 2631-1: Mechanical vibration and shock - Evaluation of human exposure to

whole-body vibration - Part 1: General requirements. The guidelines are applicable to

situations where the individual is exposed to vibration while in a seated posture.

However, the general principles may be transferable into a situation when collecting

vibration measurements between the floor and the feet. The ISO 2631-1 establishes a

health guidance caution zones (HGCZ) for vibration exposure. The HGCZ for vibration

2 2exposure between four and eight hours lies between 0.45m/s and 0.9m/s . Exposure to

WBV that places a worker within the HGCZ may result in potential health risks to the

worker, while exposures below the HGCZ have not been shown to cause any health

effects.

1.6 Effects of Vibration in Standing

Workers who are in a WBV environment are often subjected to postural stress, whether

they are seated or standing. Workers are exposed to FTV when working with equipment

16

that requires them to stand on a surface that vibrates (Eger et al, 2006). The resonant

frequency of a standing person has been identified to lie between 8-10 Hz with a second

peak at 20 Hz (Randall et al, 1997; Miwa, 1975). Studies have reported a greater

transmission of vibration to the pelvis and lower spine in the standing than sitting position

(Matsumoto et al, 2000). Greater transmissibility of FTV to the upper body during

standing could result in similar health disorders commonly associated with WBV.

Lundstrom and Holmlund in 1998 stated that WBV exposure is associated to many

physiological, psychophysical and physical factors like individual susceptibility, body

constitution and body posture, together with the frequency, direction, magnitude and

duration of the vibration that are relevant for the development of unwanted effects

(Lundstrom and Holmlund, 1998). In another study by Holmlund et al, it was stated that

erect body posture during vibration exposure results in higher impedance magnitudes

with vibration peaks located at higher frequencies (Holmlund et al, 2000). The findings

were supported by the fact that high muscle activity (as with erect compared to relaxed

body posture) is necessary to dampen vibratory waves (Wakeling and Nigg, 2001).

However, sustained muscular activity could lead to muscle fatigue, which effects

neuromuscular coordination (Ng et al, 2003) and proprioception (Taimela et al, 1999),

thereby increasing the potential risk of workplace-related injury. Exposure to WBV

affects body’s balance and results in increased postural sway (Martin et al, 1980).

Exposure to FTV in forest workers (Juntunen et al, 1983) and rock drill workers (Hirata et

al, 1995) actually cause reductions in the lower extremity nerve conduction velocity.

Also, Raynaud’s phenomenon of the toes (vibration induced white toes) was reported in

chain saw workers (Sakakibara, 1994) and underground mine workers (Hedlund, 1989)

while exposed to FTV in standing. Leduc et al. (2010) also reported that two of seven

17

miners exposed to FTV were diagnosed with Vibration White Feet (VWFt) in her

research study at Northern Ontario mine sites. Reportedly, both of the workers were

exposed to standing vibration through their feet and were also diagnosed with HAVS.

Table 1.2 shows various cases with Raynaud’s phenomenon of the toes reported in

previous research.

Table 1.2: Reported cases with Raynaud’s phenomenon of toes in vibration exposed

workers

Mills ( 1942)l) one pneumatic hammer operatorSuzuki et al. (1966)2> one rock drillerGomibuchi and Ohi one chain-saw and wood collecting machine operator(1967)1)Hashiguchi et al. ( 1988)4) three cases: a chain-saw operator,

a rock driller, a stone crusher operatorHedlund (1989)*> six cases of twenty-seven minersToibana and Ishikawa ten cases: three chain-saw operators, three rock(1990)6) drillers, and others

(Table taken from: Sakakibara H; Sympathetic responses to hand-arm vibration and

symptoms o f the foot; 1994)

Furthermore, in a case report presented by Thompson et al. (2010), the authors reported

VWFt in a mine worker (54 year old male with 18 years o f vibration exposure while

working with rock drills and roof bolters) solely from exposure to FTV (i.e. independent

of exposure to HAV). The subject was diagnosed with bilateral and symmetric

vasospastic disease (Raynaud's phenomenon) in the feet but not in the hands. Due to the

central sympathetic vasoconstrictor reflex induced vasospasm in the extremities, House et

al. (2010) recommended screening of workers exposed to HAV for any vascular

18

abnormalities in the feet. In another study, whose purpose was to rule out the

vasoconstrictive changes in the foot as being solely dependent on the sympathetic

pathway mediated by HAV exposure, researchers found that miners exposed to segmental

foot vibration had severe vasospasm of the feet than hands. This led to the conclusion that

the changes in the feet were not necessarily sympathetically induced from HAVS and

could be the direct result of segmental vibration exposure at the feet while standing. Choy

et al. (2008) has also reported white toes in a 58 year old male subject with 30 years of

vibration exposure as a rock drill operator. In the same study, researchers suggested that

symptoms of the feet must be assessed by the occupational and environmental medicine

physicians when diagnosing HAVS due to the high incidence of vasoconstrictive changes

in the feet following HAV exposure. Structural changes like thickening of the tunica

media in the foot vessels and perivascular fibrosis have also been reported in the

individuals with long-term direct vibration exposure of the foot while standing

(Hashiguchi et al, 1994). Direct exposure to FTV in the experimental animal models has

also reported sciatic nerve damage (Lundborg et al, 1987) and atrophy of the muscles of

the legs and sole (Shanskaya, 1965).

Adverse health effects during HAV exposure are associated with vibration exposure with

a frequency range of 20-50 Hz, and more than 80Hz for the fingers; whereas the risks to

the whole body are greatest in the frequency range of 4-8Hz (Griffin, 1990). The

symptoms of the feet during vibration exposure were noted when exposed to the critical

HAV frequency levels. Moreover, ISO 2631-1 places the greatest emphasis on the lower

frequency ranges (0-20 Hz), which may not adequately address the health risks at the feet.

Therefore, it might be more appropriate to determine the health risks associated with

vibration exposures at the feet by referring to the guidance in ISO 5349-1, hand-arm

19

vibration standards. However, since ISO 5349-1 standard does not contain information on

standing vibration measurement, which are well demonstrated by ISO 2631-1 standards;

the current study adapted ISO 2631-1-Mechanical vibration and shock - Evaluation of

human exposure to whole-body vibration - Part 1: General requirements; guidelines for

vibration measurement at the feet in the individuals exposed to FTV while standing.

1.7 Biodynamic Response and Transmissibility

Some understanding of the manner in which vibration is transmitted to and through the

body is necessary to understand how vibration influences human comfort, performance

and health. It is also necessary for the proper consideration of protective measures that

prevent direct contact with the vibration source (e.g. seat cushions, anti-vibration gloves

etc.) or reduces vibration transmission in the body (e.g. postural changes). Measures of

the dynamic responses of the body are represented by transfer functions, which are

categorized into two groups: those where two measures are obtained at different points

(i.e. at the driving point of vibration and a location remote from the driving point) and

those where two different measurements are obtained at the same point. The first method

is used to calculate vibration transmissibility through the body, in which the ratio of

motion at one point to motion at another point is determined. The latter case most often

involves the determination of the ratio of the force and acceleration to determine the

driving point mechanical impedance (Mansfield, 2005).

The transfer function at any frequency can be expressed as either two numbers

(magnitude and phase) or as a single complex number. The combination of the magnitude

and phase is commonly referred as the “transfer function” and the magnitude alone as the

“transmissibility” (Mansfield, 2005).

20

The equation if transmission of vibration from the floor (vibration platform) to the ankle

is considered will be:

T (f) = a gnk!e(f)/anoor(f) (Equation 1)

Where, aankie(0= acceleration measured at the ankle at frequency (f)

a n o o r ( f ) = acceleration measured at the floor at frequency (f)

Thus, if the aankie(f)/ a f l o o r ( f ) ratio is less than 1 it indicates attenuation of the vibration and

if it is more than 1, it indicates amplification of the vibration during its course through the

heel to the ankle (Mansfield, 2005).

The peak in the vibration transmissibility occurs at the resonant frequency of the tissue,

and then vibration at that frequency is amplified by a buildup of stored energy due to

repeated stretching and compression of tissue (Mansfield, 2005). As mentioned earlier,

all mechanical systems have its typical resonant frequency at which there is maximum

shear force at the tissue level. Bio-dynamic studies have identified critical frequencies for

some of the body segments and it has been reported that some type of detrimental effects

are closely related to vibration exposure, resulting in resonant behavior of the exposed

body part (Holmlund et el, 2000).

In the past, whole-body vibration transmissibility has typically been determined between

the seat surface (input) and the head (output) (Griffin, 1990). Other studies have

discussed vibration transmissibility to other body parts like the hip (Guignard, 1959),

shoulder (Rowlands, 1977), thorax (Donati and Banthoux, 1983) and cervical vertebrae

21

(Cooper, 1986; Griffin, 1990). Differences in the transmissibility from the seat to the head

have been attributed to changes in the posture of the body, head and limbs (Griffin, 1990).

The effect of neck and pelvic postures on vibration transmissibility has been reported by

Messenger and Griffin (1989). It was concluded that an anatomically erect sitting posture

would tend to increase the transmission of vibration to the head at higher frequencies but

minimize transmissibility at low vibration frequencies. Also, there is some evidence that

changes in the foot position alter seat-to-head vibration transmissibility (Rowlands and

Maslen, 1973; Rowlands, 1977 and Griffin et al, 1979; Griffin, 1990; Jack et al, 2008).

Muscle tension along the body during vibration exposure has also been identified as the

possible cause of alterations in vibration transmissibility (Guignard, 1959 and Griffin et

al, 1979; Griffin, 1990).

There are limited resources on gender differences in vibration transmissibility. Griffin and

colleagues (1982) exposed 18 male and 18 female subjects to WBV between 1-100 Hz

and found that, although the median transmissibility had the same general form, women

had significantly less vertical head motion at 2.5 Hz and significantly more vertical head

motion at 40, 50 and 63 Hz than men. In a separate study, researchers found that females

tend to absorb more vibration power per kilogram of sitting weight. However, researchers

attributed this finding to the higher body fat mass to muscle mass ratio in female

compared to their male counterparts. It was reported that fat, being viscous and inelastic,

implies a high degree of damping, and thus leads to greater vibration absorption in

females (Lundstrom and Holmlund, 1998).

Studies on the transmission of vertical floor vibration to the heads of subjects standing

erect generally suggest that vertical head vibration is similar to that when seated in an

erect posture. Paddan (1987) showed that transmissibility to all six axes of the head is

22

broadly similar whether standing or sitting erect, with the greatest motion occurring in the

mid-sagittal plane (i.e. x-axis, z-axis and pitch axis) (Griffin, 1990; Matsumoto and

Griffin, 2000). However, there was greater transmission of vertical vibration to the pelvis

and the lower spine in the standing posture than in the sitting posture at the principal

resonance (5-6 Hz) and at higher frequencies (Matsumoto, Griffin, 2000). Also, it was

found that “unlocking and slightly bending the knees” results in a small reduction in the

vibration transmissibility at any frequency below 25 Hz. Bending the knees so that they

were vertically over the toes reduced vertical transmissibility of the vibration at all

frequencies above 5 Hz (Griffin, 1990). A recent study by Caryn and Dickey (2010)

reported that the axial skeleton is exposed to large amounts of mechanical energy with

full knee extension.

The human body has a complex response to vibration that varies greatly within and

between individuals. Although there are some data showing the transmission of vibration

to the body (impedance) and also through the body (transmissibility), the complexity of

the phenomenon and the factors which influence vibration in the body is not well

understood and needs more work. Also, there is a lack of knowledge on the vibration

transmissibility through the feet and the lower body while standing on a vibration source.

Considering the increase in the reported cases with VWFt, this justifies the need for

further research in this context to prevent health hazards.

1.8 Comparison Between Hand-Arm and Foot-Ankle Response to Vibration

1.8.1 Anatomy of the Hand and Foot

(Paraphrased from Gray’s Anatomy o f the Human Body, 1918; Nor kins and Levangie,

2001)

23

The ‘wrist and hand’ in the upper extremity and ‘ankle and foot’ in the lower extremity of

the human body appears to be structurally constructed on similar principles. The

interdependence of the ankle and foot with the more proximal joints of the lower

extremities and the great weight bearing stresses to which these joints are subjected have

resulted in higher frequency of lower extremity disorders (Norkin and Levangie, 2001).

The hand and wrist consists of proximal carpal bones, middle metacarpal bones and the

terminal free mobile segment, phalanges. Similarly, in the lower extremity, the hind foot

consists of tarsal bones, mid-foot has tarsal and metatarsal bones, and the forefoot

consists of metatarsals and phalanges. The proximal row of carpal and tarsal bones

consists of cubical bones, which are chiefly concerned in distributing forces transmitted

to or from the long, weight bearing bones of the upper or lower extremities. The middle

part of the metatarsals and metacarpals provides greater surface area for the efficient

force distribution and transmission. The terminal portion of the hand and foot or

phalanges are the most movable part, to allow a large range of movement, particularly

flexion/extension.

The vascular and nerve distribution in the foot and hand are very similar. The ulnar and

radial artery supply blood to the hands whereas the medial and lateral plantar artery

supply blood to the feet. The muscles of the hand are innervated by the median and ulnar

nerves and the intrinsic muscles of the foot are innervated by the medial and lateral

plantar nerves.

However, functionally, the hand and foot have different roles. The foot forms a firm basis

of support for the body in the erect posture and helps in the propulsion of the body. In

comparison, the hand is used for functional activities and has great dexterity. Another

very marked difference lies between the metacarpal bone of the thumb and the metatarsal

24

bone of the great toe. The metacarpal bone of the thumb is constructed to permit great

mobility, is directed at an acute angle from that of the index finger, and is capable of a

considerable range of movements at its articulation with the trapezium carpal bone. On

the other hand, the metatarsal bone of the great toe is more massive and assists in

supporting the weight of the body, lies parallel with the other metatarsals, and provides

push off during the terminal stance phase of the gait cycle. (Gray’s Anatomy of the

Human Body, 1918; Norkins and Levangie, 2001).

1.8.2 Arches of the Foot and Hand

The foot consists of plantar arches to support the body weight, provide smooth propulsion

by acting as a rigid lever, shock absorption and adjust to ground contours. Although the

arch-like structure of the foot is similar to the structure of the palmar arches of the hand,

the arches of the hand serve to facilitate grasp and manipulation of objects (Norkins and

Levangie, 2001). The foot is constructed of a series of arches formed by the tarsal and

metatarsal bones, and is strengthened by the ligaments and tendons of the foot. The

main/functional arches are the transverse arch and the medial longitudinal arch (MLA).

The medial longitudinal arch is made up by the calcaneus, the talus, the navicular, the

three cuneiforms, and the first, second, and third metatarsals. The chief characteristic of

this arch is its elasticity, due to its height and to the number of small joints between its

component parts (Figure 1.1). The transverse arch is present along the medial-lateral

border o f the foot. This is formed by the curvature of the five metatarsal bones.

25

Medial longitudinal arch

lateral longitudinal arch

Figure 1.1: Pictorial Demonstration of the Arches of the Foot (Arthur’s Medical

Clipart, 2009)

The medial longitudinal arch of the foot demonstrates two extremes of anatomical

structural position, the high arch foot and the flat foot. Although all types of arches of the

foot help to support the erect body posture during weight bearing and dynamic activities,

the MLA has been found clinically significant in these arch-related pathologies. Muscular

imbalances, structural malalignments of the joints, gait abnormalities, impaired joint

mechanics and repetitive stress injuries are caused by either high arch or flat arch foot

(Franco, 1986; Kisner and Colby, 2002).

1.8.3 Assessment of the Foot Arch

The human foot can have a range of structural variations, more so than any other part of

the body. Its functional mechanics are influenced by its structure, particularly the height

of the MLA (Cavanagh et al, 1987; Shiang et al, 1998; McCrory et al, 1997). Several

methods have been used in the past to evaluate the MLA of the foot including foot-prints

(Hawes et al, 1992), direct observation (Giladi et al, 1985), radiographs (McCrory et al,

1997; Cavanagh et al, 1997), photographs (Cowan et al, 1993), and ultrasound (Honning

26

et al, 1985). In 1987, Cavanagh and Rodgers put forth an arch index measure, which is

the ratio of the area of the middle third of the toeless footprint (truncated foot) to the total

footprint area. The arch index has been recognized as a useful tool in assessing the

structural characteristics of the foot. An arch index of less than 0.21 is indicative of a high

arch foot and an arch index of greater than 0.26 indicates a low arch foot. The arch index

has also been shown to be a valid predictor of arch height and showed strong association

to navicular height measured by the radiographic technique (McCrory et al, 1997).

Moreover, the arch index has been used as a reliable technique to determine the incidence

and prevalence of flat footedness in the population (Rose et al, 1985; Igbigbi et al, 2002).

1.8.4 Bio-dynamics and Vibration Transmissibility of the Hand

Although magnitude, frequency, duration and direction of the vibration are considered

prime factors that determine the vibration transmissibility and its effects, there are also

some other important factors associated with HAVS. Vibration transmissibility in the

hand-arm system is defined as the ratio of the vibration measured on the hand-arm system

and the input vibration on the hand-tool interface (Dong et al, 2005). As defined by Dong

et al, the bio-dynamic force is the vibration energy transmitted from the handle of the

equipment to the hand-arm system, and the internal body dynamics which lead to the

further transmission of this vibration energy to the other locations of the hand-arm

system, are defined as bio-dynamic stresses (Dong et al, 2005). It was stated that the

stresses caused by the vibration energy are responsible for the damage caused to the tissue

following vibration exposure (Dong et al, 2005).

Vibration transmissibility through the hand-arm system is largely determined by the bio­

dynamic response of the hand to vibration exposure, which depends on the physical

characteristics of the hand, hand grip, tool-operating technique, area of hand in contact

with the tool, push force, and elbow posture (Griffin, 1990). Dong et al. stated that the

surface area of the hand in contact with the vibration source plays a significant role in the

vibration transmissibility, which is estimated through the apparent mass or mechanical

impedance of the hand-arm surface in contact with the vibrating tool (Dong et al, 2005).

It has been reported that increased coupling between the hand and the handle of the

equipment tends to increase the impedance at the hand. Griffin (1990) reported that a

moderate grip force is associated with greater impedance than a light grip over the handle

of the tool in use. Researchers also reported that variations in the angle at the elbow joint

while operating a hand held device also altered the impedance measured at the hand. The

greatest transmission of vibration was reported while working in a closed biomechanical

chain with the extended elbow (Griffin, 1990).

The vibration-induced stresses and strains on the fingers are different from the palm-

wrist-arm system, as the fingers are structurally different and offer lower impedance

(Griffin, 1990). In another study, Dong et al, (2010) reported that the impedance

distributed at the fingers is less than at the palm at frequencies below 100 Hz because the

effective mass of the fingers at lower frequencies is less than that of the palm. There is a

difference in the response and mechanism of injury of the hand and fingers to the

vibration exposure at different frequencies (Dong et al, 2010). Vibration power or

vibration exposure measured at the finger tip may be more closely associated with VWF,

whereas vibration power measured at the palm-wrist level may have a better correlation

with disorders of the wrist and arm. Thus, devices that are effective in attenuating

28

vibration at the palm level may not attenuate vibration as efficiently at the fingers (Dong

et al, 2005). Further, it was reported that the efficiency of the anti-vibration gloves was

dependent on the apparent mass of the exposed area of the hand or finger. It was stated

that the higher the apparent mass of the exposed area of the hand-arm system the more

effective the gloves were at attenuating the vibration (Dong et al, 2005).

Since the physiological and pathological response of the feet to vibration is comparable to

the hand-arm system, as represented in various studies (Hedlund, 1989; Sakakibara et al,

1991; Hirata et al, 1995; Sakakibara et al, 1994; Thompson et al, 2010; Choy et al, 2008),

a similar approach can be used to evaluate the bio-dynamic response of the foot. Based on

the difference in impedance distributed at the fingers and hand (Dong et al, 2010), it is

hypothesized that there could be differences in the vibration impedance distributed at the

toes and the sole of the feet. Also, with reference to HAV, FTV may also depend upon the

apparent mass of the foot and toes, which may be dependent on physical factors like the

surface area of the feet in contact with the vibrating surface, body weight, angle of the

hip-knee-ankle, etc. There is limited knowledge on the bio-dynamic response of the foot

to FTV. Future research can be done to understand the of the foot to vibration exposure,

which will be helpful in devising measures to attenuate vibration that enters the body

through the feet.

1.9 Strategies to Reduce Vibration

Several strategies can be adopted to reduce harmful vibration from entering the body.

Ergonomic measures like decreased tool vibration, reduced exposure times, regular

29

maintenance of equipment, and the use of personal protective equipment are often

recommended to limit exposure to vibration. Proper training with respect to driving and

equipment use and regular health monitoring could also help to limit negative health

outcomes associated with HAV and WBV exposure (Mansfield, 2005). Strategies

suggested to reduce HAV and WBV might also be helpful to reduce FTV.

1.9.1 Reduction Strategies for WBV Exposure

Ergonomics best practices suggest interventions should focus on either reducing the

magnitude of vibration exposure or reducing the duration of the vibration exposure to

minimize the overall health effect o f the vibration exposure (Mansfield, 2005).

Engineering solutions like improved axle suspension, engine mounting or suspension

seats can be implemented in heavy vehicles to minimize vibration transmission to the

operator (Mansfield, 2005). Maintenance of the road has reportedly helped in reducing

shocks and harmful vibrations experienced by heavy equipment operators (Mansfield,

2005). A reduction in vibration dose can also be achieved by monitoring the speed of

vehicles, as several operators have reported lower speeds result in less vibration

transmitted to the vehicle operator (Mansfield, 2005; Eger et al, 2011). Also, multi­

cylinder engines have been reported to have higher dominant frequencies than single

cylinder engines. Considering the fact that WBV effects are multifold at frequencies less

than 20Hz, multi-cylinder engines can be an ideal solution for reducing whole body

vibration effects (Mansfield, 2005). Studies have also suggested that isolating the

vibration source from the body of the equipment to minimize the vibration transmission

into the body of the equipment, as an effective measure. Thus, mounting the engine of the

30

vehicle on a resilient mounting to isolate engine vibration from the chassis vibration has

been found as an effective measure in reducing vibration (Mansfield, 2005).

In 2008, Mayton tested ergonomically modified suspension seats in newer trucks and

reported that the improved seat quality provided better overall isolation to drivers from

WBV exposure compared to older seats. In another study, a new car seat design which

reduced contact between the seat and the ischial tuberosities, helped in reducing both the

contact pressure and amplitude of vibration transmitted through the body (Makhsous et al,

2005).

Canadian Institute of Mining, Edmonton in 2004 proposed an onboard warning system

based on ISO 2631-1 to help operators monitor the vibration levels experienced in a

heavy hauler. The onboard system consists of light signals to determine the level of

vibration exposure where, green represents a safe zone, yellow a caution zone, and red-a

danger zone. The onboard system also estimates the overall vibration exposure for the

entire shift and warns the worker when he/she is over a recommended daily exposure

limit.

If engineering solutions cannot be achieved then reducing the duration of vibration

exposure should be considered as the ideal measure to reduce vibration exposure

(Mansfield, 2005). Training to ensure an ergonomically sound posture to operate heavy

equipment should also be considered as an important measure to reduce the health effects

associated with vibration exposure. For example, improved seat designs may be helpful

in the maintenance of a good posture in the vibration environment (Griffin, 1990).

Training on the proper technique to use the equipment is also very important in reducing

31

the amount of vibration that enters the body (Mansfield, 2005). Lastly, all workers

should undergo routine medical check-ups at regular intervals to monitor their vibration

exposure and health status (Griffin, 1990).

1.9.2 Reduction Strategies for HAV Exposure

There are some general techniques that can be adapted to reduce hand-arm vibration

exposure. Vibration can be transmitted to the hands and arms of operators from vibrating

tools, vibrating machinery or vibrating work pieces. Depending on the nature of the work,

vibration can enter one arm only or both arms simultaneously and travel up to the

shoulder (ISO 5349-1, 1986). In order to reduce hand-arm vibration, strategies are

employed to reduce vibration at the source and/or to reduce vibration transmitted to the

worker. Engineering controls focus on manufacturing low emission vibration tools which

have features such as vibration-reducing handles (Mansfield, 2005). Hand tools should

be ergonomically designed to minimize the need for high grip forces and hand and finger

exposure. Tools should also avoid the emission of cold gases on worker’s hands as it

reduces the vascular supply to the localized tissue and increases the risk of vibration

induced white finger (Griffin, 1990). Medical management is also important. Workers

who are regularly exposed to vibration should be advised on the adverse effects of long­

term vibration exposure and a routine health check-up should be conducted to screen

workers for HA VS. Appropriate warnings, such as trigger times, should be tagged to tools

known to emit harmful vibrations (Mansfield, 2005).

Individual training in the proper handling and knowledge of the equipment is also

important to differentiate any unwanted change in the equipment behaviour (Mansfield,

2005). Unwanted vibration exposure must be avoided and tools should not be held when

32

not in use. Wearing adequate clothing, use of appropriate personal protective equipment

(PPE) and keeping the hands dry and warm are also very important while working with

hand held vibration tools. The severity of HAVS has been reported to be higher in

smokers and it is highly recommended that workers avoid smoking if their work involves

vibrating tools (Griffin, 1990).

The use of personal protective equipment such as anti-vibration gloves is also

recommended to operators working with vibration tools. ISO approved (ISO-10819) anti­

vibration gloves have been found to attenuate harmful vibrations from entering the hand-

arm system during vibration exposure (Jetzer et al, 2003). However, the effectiveness of

anti-vibration gloves depends on the exposed area of the hand. It was reported by Dong et

al. (2005) that the higher the apparent mass of the exposed area of the hand the better the

gloves were at attenuating vibration. Also, the grip force was reported to affect the

transmissibility of these anti-vibration gloves. Different gloves have different material

properties and it was found that the stiffness of some of the material increased with the

application of force, which led to an increase in vibration transmissibility (Dong et al,

2005). As mentioned earlier, it is also important to note that the same anti-vibration glove

cannot be effective at attenuating hand and finger vibration because of differences in the

physiological and bio-mechanical properties of the hand and fingers (Dong et al, 2005).

1.9.3 Reduction Strategies for FTV Exposure

Some of the general measures like engineering controls, ergonomic modifications and

manufacturing tools with the main aim to minimize vibration emission, are the key

measures for reducing vibration exposure to any body part. Isolated standing areas on

drilling platforms have been reportedly used to reduce vibration that enters through the

33

feet (Leduc et al, 2011). Personal protective equipment like anti-vibration mats, boots

and insoles has also been introduced to the workers to help attenuate FTV. However the

ability of these PPE to attenuate vibration has yet to be proved. A recent study by Leduc

et al. (2011) identified mats that were effective in attenuating some vibration at the feet.

However, there is no reported literature on the efficacy o f insoles and boots used by

operators exposed to FTV in reducing vibration magnitude at the feet. Therefore, future

research to determine the effectiveness o f mining boots and insoles should be conducted.

1.10 Thesis Outline

Long-term segmental vibration exposure at the feet can lead to vibration induced white

feet (VWFt) (Thompson et al, 2010; Choy et al, 2008; Hedlund, 1989). Other

pathological findings related to neurovascular structures, musculoskeletal structures,

sympathetic nervous system etc., have also been reported following vibration exposure at

the feet (Choy et al, 2008; Takeuchi et al, 1986; Hirata et al, 1995; Hashiguchi et al,

1994). However, there is limited knowledge on the bio-dynamic response of the feet to

FTV and less is known about appropriate interventions to attenuate FTV. Therefore, the

objectives of this study are four fold: 1) to measure vibration transmissibility through the

foot (between the floor and ankle); 2) to determine if floor-to-ankle transmissibility is

significantly different between males and females; 3) to determine the influence of arch

types (foot surface area in contact with the vibration platform) on floor-to-ankle vibration

transmissibility; and 4) to evaluate the efficacy of mining boots and “anti-vibration”

insoles in FTV attenuation.

Chapter 1: Literature Review: This chapter includes background knowledge on work

that has been done in the field of vibration, including vibration terminologies and

nomenclature, types of vibration exposure, international standards that comment on

vibration measurement techniques, reported occupational health hazards due to vibration

exposure and necessary steps to combat harmful vibrations. At each step in the literature

an attempt has been made to relate the importance of previous research in the study of

FTV. Also the chapter includes information on reported cases of foot ailments due to

vibration exposure and the patho-physiology behind it. The basic intent of this chapter is

to justify the present research work, which deals with health effects associated with FTV

and interventions to reduce its harmful effects.

Chapters 2 and 3 are written as papers ready for journal submission. Specific objectives

of Chapter 2 are as follows.:

a) to determine vibration transmissibility between the floor and the ankle in standing

individuals exposed to two levels of FTV

b) to determine if there is a significant difference in floor-to-ankle vibration

transmissibility between males and females when exposed to FTV

c) to determine if there is a significant difference in floor-to-ankle vibration

transmissibility with the surface area of the foot in contact with the vibration

surface

d) to determine if there are any differences in floor-to-ankle vibration transmissibility

with participant body mass.

e) to determine if there is a significant difference in subjective discomfort reported

by males and females when exposed to FTV

35

Specific objectives of Chapter 3 are:

a) to measure and document the vibration transmissibility properties of three

commercially available anti-vibration insoles when exposed to low frequency and

high frequency vibration.

b) to measure and document the vibration transmissibility properties o f two

commercially available mining boots when exposed to low frequency and high

frequency vibration

c) to determine if there is a significant difference in the subjective discomfort scores

when participants are exposed to FTV while wearing different insoles and mining

boots.

In the final chapter. Chapter 4. conclusions derived from Chapter 2 and 3 are discussed

along with limitations and future directions. The relevance of the work to the mining

industry and workers exposed to FTV is also discussed.

36

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www.arthursclipart.org/medical/skeletal/arches%20of%20the%20foot.gif

48

CHAPTER 2

Examination of floor-to-ankle vibration transmissibility and subjective discomfort of males and females with different foot arch classifications when exposed to foot-

transmitted vibration

49

Abstract

Research concerning foot-transmitted vibration (FTV) is limited despite evidence of

vibration induced white feet. There has been extensive research on the bio-dynamic

response and on adverse health effects resulting from exposure to vibration when seated

or vibration when gripping power tools. However, research associated with FTV is

limited despite evidence of vibration induced white feet. Therefore the main objective of

the study was to determine vibration transmissibility between the floor and the ankle

while standing. Specific objectives were 1) to determine if there were any significant

differences in floor-to-ankle vibration transmissibility between males and females; 2) to

determine if there were any significant differences in floor-to-ankle vibration

transmissibility by foot arch type; 3) to determine if there were any significant differences

in floor-to-ankle vibration transmissibility by body weight; and 4) to determine if there

were any significant differences in reported discomfort by gender or vibration exposure

frequency. Sixteen participants (eight male and eight female) were exposed to two-levels

of vibration, while standing on a low frequency (3.15-lOHz) and a high frequency (40Hz)

vibration platform. The vibration was recorded at the floor and the ankle with two tri-

axial accelerometers in accordance with the ISO 2631-1 standard. Participants reported

body discomfort on a 9-point discomfort scale following each vibration trial. Frequency-

weighted acceleration in the z-axis (vertical axis) entering the foot (Fawz) was compared

to frequency-weighted acceleration in the z-axis at the ankle (Aawz). The percentage

difference between Aawz and Fawz was taken as a measure of vibration transmissibility

between the floor and the ankle. Multivariate analysis was performed with a selected

alpha level of 0.05 and six degree of freedom to analyze the vibration transmissibility (y-

axis) against frequency, gender, mass and foot arch type (x-axis). There was a significant

50

difference in vibration transmissibility at two frequencies (F = 3.27, p= 0.001) with less

vibration transmitted to the ankle at high frequency (72.61+/-33.99) than low frequency

(106.27+/-9.53) vibration exposure. There was no significant difference in floor-to-ankle

transmissibility by gender (F=3.27, p=0.715) or participant body weight (F=3.27, p=

0.849). Also there was no significant difference in vibration transmissibility with

differences in foot arch type (F=3.27, p= 0.515).

51

2.1 Introduction

People can be exposed to vibration in the workplace and during leisure activities.

Vehicles, machinery and industrial activities can expose people to different forms of

mechanical vibration, which can interfere with comfort, activities and health (ISO 2631 -

1; 1997). In the workplace, people can be exposed to vibration when standing, sitting and

in some cases lying while in contact with a vibration source. Vibration exposure is

becoming one of the latent causes for occupational health hazard in many industries.

Regular and long-term exposure to vibration can lead to vascular, musculoskeletal,

neurological and other systemic disorders (Sakakibara et al, 1994; Abercromby et al,

2007). Acute health effects reported from whole-body vibration (WBV) exposure include

loss of visual acuity, postural stability and manual control; whereas chronic health effects

include low back pain, early degeneration of the spine, herniated discs, neurological,

digestive and circulatory disorders (Mayton et al, 2008). Similarly, workers exposed to

hand-arm vibration (HAV) have reported episodes of blanching of the fingers; tingling,

numbness and reduced tactile sensation in the hand and fingers; and also reduction in

muscular strength and dexterity (EU Guide to good practice on HAV, 2006; Cohen et al,

1995; Bovenzi, 1998). Associated changes with hand-arm vibration syndrome (HAVS)

include thickening of the tunica media of the blood vessels, demyelination of the neural

tissues and collagen deposition in the connective tissues of the exposed part (Takeuchi et

al, 1986).

Vibration exposure during standing and the resulting health effects to the feet have

received little attention and the impact of vibration frequency on the feet is not clearly

understood. Workers are exposed to foot transmitted vibration (FTV) when working with

52

equipment that requires them to stand on a surface that vibrates (Eger et al, 2006). Health

effects like neurological symptoms typically observed in the hands after occupational

exposure to HAV have been reproduced in the feet of workers exposed to similar

vibration frequencies and accelerations (Griffin, 2008). Other studies have also reported a

reduction in the nerve conduction velocities in the lower extremity (Juntunen et al, 1983;

Hirata et al, 1995); Raynaud’s phenomenon of the toes (Hedlund, 1989; Choy et al, 2008;

Thompson et al, 2010; Leduc et al, 2010); thickening of the blood vessel walls and

increased collagen deposits in the connective tissue (Hashiguchi et al, 1994); and

reduction in the lower extremity skin temperature (Sakakibara et al, 1991).

Vibration exposure via the feet has also been found to cause muscle and nerve fiber

degeneration in animal models (Shanskaya et al, 1965 and Lundborg et al, 1989). It has

been reported that changes in the feet are induced by stimulation of sympathetic nervous

system in the workers with HA VS when exposed to HAV (Sakakibara H, 1994; House et

al, 2010). However, some of the studies have also identified vibration white foot (VWFt)

independent of HAVS in individuals exposed to segmental FTV (Thompson et al, 2010;

Hedlund, 1989). These findings throw light on the occurrence of VWFt in workers who

are exposed to segmental lower extremity vibration in standing, independent of HAV

exposure. The vibration frequency in both the case reports that led to the development of

VWFt was reported to be 40Hz (Thompson et al, 2010; Hedlund, 1989).

Different parts of the body have their own resonant frequency and it has been reported

that some types of detrimental health effects are associated with exposure at resonant

vibration frequencies (Holmlund et al, 2001). The hand-arm system is reported to have a

resonant frequency between 20-50Hz and frequencies above 80Hz are believed to be

more harmful for the fingers (Dong et al, 2004; Dong et al, 2010). On the other hand,

frequencies in the range of 4-8Hz are associated with seated spinal resonance (Griffin,

1990). The resonant frequency of the foot and toes has not been documented. During an

underground mine study by Leduc et al, (2011), workers were exposed to FTV between

3.15-6.3Hz (WBV range) and 31.5-40Hz (HAV range). Moreover, workers consistently

exposed to vibration between 31.5-40Hz had an increased diagnosis of VWFt (Leduc et

al, 2011).

Evidence from the hand-arm vibration literature indicates factors other than vibration

exposure frequency also influence vibration transmissibility. Vibration transmissibility in

the hand-arm system is defined as the ratio of the vibration measured on the hand-arm

system and the input vibration on the hand-tool interface (Dong et al, 2005). Vibration

transmissibility through the hand-arm system is largely determined by the bio-dynamic

response of the hand which depends on the physical characteristics of the hand, hand grip,

tool-operating technique and area of hand in contact with the tool, push force, elbow

posture etc. (Griffin, 1990). For example, a moderate grip force is associated with greater

impedance (and transmissibility) than a light grip over the handle of the tool in use

(Griffin, 1990). There is also greater vibration transmissibility to the arm and shoulder

when operating vibration tools with extended elbow (Adewusi et al. 2011). Similarly,

greater vertical transmission of FTV has been reported while working with fully extended

knees compared to slightly flexed knees (Caryn and Dickey, 2010; Griffin, 1990).

However, the influence of mass (force) or surface area in contact with the vibration

source, on foot transmitted vibration has yet to be documented.

Researchers have also used comfort (discomfort) as a measure to understand the effect of

vibration exposure. A comfortable stimulus is defined as the one where the subjects do

not have to change their activity or reduce vibration exposure magnitude (Mansfield,

2005). Depending on the intensity and characteristics of vibration, a vibration stimulus

might not be painful but produce a sense of discomfort (Mansfield, 2005). Furthermore,

several researchers have exposed participants to short periods of vibration and accurately

obtained discomfort reports (Dickey et al, 2006). For example, Dickey et al. (2006)

reported that there was no significant difference in the reported discomfort between a 15

or 20 second vibration exposure, or a 5 or 10 second rest duration when participants were

exposed to single axis, planar or six degree of freedom vibration in a lab setting.

Given the limited research documenting the transmission of FTV through the foot, but

evidence of VIWFt (Thompson et al, 2010; Leduc et al, 2011), the objectives of the

present study were;

1) to determine if there are any significant differences in floor-to-ankle vibration

transmissibility when participants were exposed to low-frequency FTV and high-

frequency FTV;

2) to determine if there are any significant differences in floor-to-ankle vibration

transmissibility between males and females;

3) to determine if there are any differences in floor-to-ankle vibration transmissibility for

different foot arch types;

4) to determine if there are any differences in floor-to-ankle vibration transmissibility

with participant body mass.

55

5) to determine if there are any significant differences in participant reported discomfort

by gender or FTV exposure frequency

Based on the literature review it was hypothesized that:

1. there will be greater vibration transmissibility through the foot during high

frequency vibration exposure, since there has been greater incidences of VWFt

reported at higher vibration exposure frequencies (Thompson et al, 2010; Leduc et

al, 2010; Hedlund, 1989).

2. there will be less vibration transmissibility in females compared to males as

females typically have a higher body fat to muscle mass ratio (Lundstrom and

Holmlund, 1998).

3. there will be less vibration transmissibility in individuals with a high foot arch due

to the reduced surface area of the foot in contact with the vibration surface

(Griffin, 1990).

4. female participants will report less discomfort than the male participants because

the overall vibration transmissibility will be lower in females.

5. there will be a greater floor-to-ankle vibration transmissibility for heavier

participants based on evidence from HAV exposure that found an increase in

HAV transmissibility with increased grip force (Griffin, 1990).

56

2.2 Methodology

The research study was approved by Laurentian University’s Research Ethics Board and

informed consent was provided.

2.2.1 Participants

Sixteen participants (eight males and eight females) with a mean age of 26 years (males)

and 20 years (females), mean height of 171 cm (males) and 165.7 cm (females), and a

mean mass of 75 kg (males) and 67.1 kg (females) were recruited by convenient

sampling. The demographic data are presented along with baseline musculoskeletal

discomfort reports in Table 2.1. Participants were ruled out for past history of concussion,

any fracture in the previous six months, diabetes, neurological disorders, peripheral

vascular disorders, back pain, or motion sickness before being cleared to participate in the

study.

2.2.2 Vibration Exposure

Two vibration profiles were generated to expose participants to FTV with a dominant

frequency below 10Hz and FTV with a dominant frequency between 30-40Hz. A custom

made vibration simulator in the Biomechanics Lab at Laurentian University generated the

lower frequency profile and an exercise vibration platform (Power Plate North American,

Inc., Irvine, CA) was used to generate the higher frequency vibration. The equipment was

previously used in a laboratory study by Leduc et al. 2011 to evaluate FTV and the author

adapted similar methods during data collection.

57

Table 2.1: Demographic Data and Pre-test Discomfort Rating

Participants Gender Mass (kg) Height (cm) Age(Years)

Initial Discomfort (0-9)

1 Male 63.6 167.5 27 0

2 Male 95.5 177.5 38 0

3 Male 82.3 171 23 0

4 Male 66.4 175.5 24 0

5 Male 86.4 173 26 0

6 Male 69.1 164 25 0

7 Male 70.9 170 23 0

8 Male 65.9 170 23 0

9 Female 62.5 164 21 0

10 Female 61.8 166 20 0

11 Female 57.3 163 19 0

12 Female 102.3 175 19 0

13 Female 50.9 161 20 0

14 Female 77.3 161 20 0

15 Female 72.7 171 20 0

16 Female 52.3 165 23 0

The lower frequency profile was selected to replicate the dominant frequency associated

with operating a locomotive in an underground mine, while the higher frequency was

selected to simulate FTV experienced when standing on a drilling platform or

underground raise platform (Leduc et al, 2010; Leduc et al, 2011). Refer to Table 2.2 for

details on the vibration profiles used in the experiment.

58

Table 2.2: Summary of the vibration characteristics

Vibration

Profile

Profile Details

Dominant Frequency Frequency-weighted r.m.s.

acceleration

1 3.15-10 Hz l.lm /s2-2 m/s2

2 40 Hz 22.1m/s2

2.2.3 Vibration Measurement

Two Series 2 10G MF tri-axial accelerometers (NexGen Ergonomics, Montreal, QC)

were used to record vibration at the platform and vibration transmitted from the floor to

the ankle (Figure 2.1). Vibration data were collected with a 500Hz sampling frequency, in

accordance with ISO 2631-1 standards and stored on two portable dataloggers, DataLOG

II P3X8 (Biometrics, Gwent, UK) (Figure 2.1).

2.2.3.1 Vibration Measurement at the Platform

A tri-axial accelerometer was mounted in a wooden foot-board which was a replica of a

Brannock device with cut out space at the heel to secure the accelerometer (Figure 2.1).

The wooden foot-board was placed on top of the vibration platform so that the

accelerometers were in contact with the vibrating surface. The participants were

instructed to stand on the wooden foot-board so that the lateral malleolus of the ankle

(where the ankle accelerometer was secured) stayed in line with the floor accelerometer.

Figure 2.1: Placement of accelerometers: a) Recording at the ankle; b) Recording at

the floor. Picture shows replication of the Brannock device with a cut out at the end

for the accelerometer. The participant stood on this apparatus with his/her heel

aligned over the accelerometer, c) Data logger used to record vibration.

2.2.3.2 Vibration Measurement at the Ankle

The tri-axial accelerometer was mounted on the lateral malleolus of each participant’s left

ankle (Fig 2.1). The accelerometer was secured over the bony prominence with double­

sided common stationary velcro and a stretchable wrapping tape (Fig 2.2). The

participants were provided with a pair of typical athletic socks, which they wore over the

ankle accelerometer while standing on the vibration platform. The accelerometer was

aligned with the vertical axis and calibrated each time prior to recording vibration. The

angular deviation of the accelerometer was maintained well within 15 degrees from the

vertical axis as suggested in the ISO 2631-1 standard guidelines. The participants did not

wear any other footwear during data collection.

Figure 2.2: Accelerometer placed on the lateral malleolus of the ankle and secured

by elastic taping.

61

2.2.4 Foot Arch Assessment

In the studies on HAV, researchers have reported that the area of the hand in contact with

the hand-held vibrating tools play an important role in the vibration transmissibility

through the hand and up to the shoulders (Dong et al, 2005; Griffin 1990). So, during the

experiment, the foot arch type of each participant was assessed as a measure of the

surface area of the foot in contact with the vibration platform while standing. The foot

print technique and Arch Index was used to measure the foot arch of each individual

(Cavanagh and Rodgers, 1987).

The Arch Index is defined as the ratio of the area of the middle third of the toeless

footprint (truncated foot) to the total footprint area (Figure 2.3) and is considered a usefiil

and reliable tool in the assessment of the medial foot arch (Rose et al, 1985; Igbigbi et al,

2002). An Arch Index of less than 0.21 is indicative of a high arch foot and an arch index

of greater than 0.26 indicates a low arch (Cavanagh and Rodgers, 1987).

The procedure, as stated by Cavanagh and Rodgers in 1987, was used to calculate the

Arch Index. Participants were asked to dip their left foot into a box containing edible

colorant and were subsequently asked to step onto graph paper of 0.36cm grid with their

full body weight to leave their foot impression on the paper. The foot impression was

allowed to dry completely and then the Arch Index was calculated using the Cavanagh

and Rodgers equation (Figure 2.3).

62

O q

L/3

L/3

L/3

Figure 2.3: Foot print for the measurement of the Arch Index. Marked areas A, B

and C show the area of the forefoot, mid foot and hind foot of the foot print,

respectively. Arch Index= B/A+B+C (Figure from the study by Stavlas et al, 2005)

2.2.5 Discomfort Measurement

A nine point unipolar continuous type verbal discomfort scale, with zero indicating an

absence of discomfort and nine indicating maximum discomfort, was used to record

participant discomfort scores (Dempsey et al, 1977). The participants were asked to

verbally report their discomfort at the start of the experiment (to serve as a baseline) and

subsequently after each 20 second vibration trial (Dickey et al, 2006). The participants

were provided with a body chart (Appendix 1) that showed different body segments and

were instructed to point out the areas of discomfort on the chart and appropriately report

the level of discomfort experienced on the nine-point scale. Discomfort in the area of the

63

head, neck, back, and/or shoulders/arms was classified as upper body (UB) discomfort,

while discomfort in the feet, knees, thighs and buttocks was classified as lower body (LB)

discomfort. The discomfort scores reported for the different body parts were summed up

on the basis of their location in either the UB or LB region and a single mean value was

calculated to represent the total UB and LB discomfort for each participant.

2.2.6 Floor-to-Ankle Vibration Transmissibility Measurement

Floor to ankle vibration transmissibility was measured by comparing frequency-weighted

acceleration in the z-axis entering the foot (Fawz) to frequency-weighted acceleration in

the z-axis at the ankle (Aawz). The percent difference between Aawz, and Fawz was taken

as a measure of vibration transmissibility from the floor to the ankle (Equation 1). Values

greater than 100% were indicative of vibration amplification between the floor and the

ankle, while values less than 100% were indicative of vibration attenuation.

T (f) = Aawz / Fawz X 100 Equation 1

Where, T= Transmissibility

Aawz= frequency-weighted acceleration in the z-axis at the ankle

Fawz= frequency-weighted acceleration in the z-axis entering the foot

2.2.7 Data Collection Procedure

A randomized block design was used for the experiment. One block exposed participants

to vibration in the 3.15-10Hz range and the second block exposed the participant to

64

vibration frequency of 40Hz. Participants were given an opportunity to experience the

FTV prior to data collection and were asked to hold onto a handrail in front o f each

vibration platform (isolated from the body of the vibration equipment) and to avoid full

knee extension during the vibration trial.

Participants were exposed to 20 seconds of FTV per trial, repeated twice, with 10 seconds

of rest (no vibration) between trials. The block order was randomized. In total,

participants were exposed to twelve 20 second FTV exposures (six at profile 1 and six at

profile 2). At the end of each vibration trial, during the rest period, the participants were

asked to rate their discomfort score on the nine-point discomfort scale.

Prior to collecting FTV data, each participant’s foot impression was obtained using the

edible color ink for the foot arch assessment before mounting the ankle accelerometer.

2.2.8 Data Analysis

The data were processed in accordance with the guidelines provided by ISO 2631-1 using

Vibration Analysis Toolkit v. 5.0 (NexGen Ergonomics, Montreal, QC, CND) software.

The frequency-weighted root mean square acceleration was calculated (aw) and expressed•n

in meters per second squared (m/s ). The frequency weightings applied, as listed in ISO

2631-1 were: x-axis=Wd, y-axis=Wd and z-axis=z'W\i (Figure 2.4). Floor-to-ankle vibration

transmissibility was calculated according to Equation 1.

65

x-axis

Figure 2.4: Axis orientation of the ankle accelerometer. The accelerometer was

aligned with the vertical axis and calibrated each time prior to recording vibration.

The angular deviation of the accelerometer was maintained well within IS degrees

from the vertical axis, as suggested in the ISO 2631-1 standard guidelines.

2.2.9 Statistical Analysis

The dependent variables were vibration transmissibility percentage and the reported

discomfort scores by the participants; whereas gender, body mass, vibration frequency,

and arch types were independent variables. To analyze the difference in the vibration

transmissibility (continuous data) and reported discomfort (continuous data) with respect

to exposed frequency, gender, body mass and foot arch type (continuous set of data), a

general linear model analysis of variance (GLM ANOVA) was performed with a selected

alpha level of 0.05.

66

2.3 Results

2.3.1 Floor-to-Ankle Vibration Transmissibility

A multivariate analysis with six degrees of freedom was performed to analyze the

transmissibility (about y-axis of the graph) against frequency, gender, mass and foot arch

type (about x-axis of the graph). We hypothesized that there would be greater floor-to-

ankle vibration transmissibility under a higher frequency FTV. There was a significant

difference in vibration transmissibility at the two vibration profiles (F = 3.27, p= 0.001),

with floor-to-ankle transmissibility being lower during exposure to high frequency

vibration (72.61+33.99) than low frequency vibration (106.27+9.53). Thus, the

hypothesis was not supported (Table 2.3; also refer to Appendix 3).

We hypothesized that females would transmit less vibration than males. However, there

was no significant difference in floor-to-ankle transmissibility by gender (F=3.27,

p=0.715).

We also hypothesized that participants with high foot arch type would attenuate more

vibration due to less surface area in contact with the vibration platform. However, there

was no significant difference in floor to ankle transmissibility with differences in foot

arch type (F=3.27, p= 0.515). Therefore, the hypothesis was rejected (Table 2.3 and 2.4;

Figure 2,5).

Also, there was no significant difference in floor to ankle vibration transmissibility by

differences in participant body mass (p= 0.849) (Table 2.4). Thus, the hypothesis was not

supported.

67

Table 2.3: Multivariate Analysis: GLM ANOVA- Transmissibility versus gender, frequency, mass, discomfort and foot arch type

Predictor Coef SE Coef T P

Constant 133.74 29.42 4.55 0.000

Gender 3.537 9.565 0.37 0.715

Frequency -46.77 11.78 -3.97 0.001

Mass -1.383 7.192 -0.19 0.849

Discom U.B -0.1596 0.5300 -0.30 0.766

Discom L.B 0.7898 0.5426 1.46 0.158

Foot Arch 4.443 6.727 0.66 0.515

68

Table 2.4: Mean vibration transmissibility in the males and females with different foot arch types at low frequency and high frequency vibration exposure

Arch Types Transmissibility

Low Frequency High Frequency

MALE High

Medium

Flat

107.9 (2.7)

107.9(11.5)

109.72 (3.8)

96.3 (44.6)

101.2(25.3}

37.58(12.6)

FEMALE High

Medium

Flat

109.68(11.9)

96.66 (10.4)

105.6 (6.9)

36.78 (12.4)

83.22 (49.3)

74.88 (22.4)

69

a

1= Male

2= Female

1= 50-68 kg

2= 69-86 Kg

3= >87 Kg

Data Means

110

100

90

80-1

g 70

{

90

80

70

Gender Frequency

* ... r " W\

1 2 1 2Mass Foot Arch

1= L.F

2= H.F

d1= Flat

2 =

Medium

3= High

Figure 2.5: Main effect plot for vibration transmissibility versus a) Gender, (b) frequency, (c) mass and (d) foot arch type

Interaction Plot for Discom L.BData Means

2 3 1 2 3. 40 Gender

-#—■ 1- m ~ 2

Frequency12

Mass12 3

Figure 2.6: Interaction plot for vibration transmissibility versus a) Gender, (b) frequency, (c) mass and (d) foot arch type

7 0

2.3.2 Discomfort Score

The mean discomfort score for the UB and LB was calculated from the verbally reported

discomfort in the UB and LB segments on a nine-point discomfort scale. The discomfort

scores reported for different body parts were summed up on the basis of their location in

the UB or LB segment and a single mean value was calculated to represent the total UB

and LB discomfort individually (Appendix 3-Table 3a and 3b).

A multivariate analysis with six degree of freedom was performed to determine if any

significant difference existed between transmissibility and reported discomfort. We

hypothesized that there would be greater subjective discomfort at high frequency

vibration exposure and that females would report lower discomfort scores than males.

There was no significant difference in reported discomfort for the UB (F= 3.27; p =

0.766) or LB discomfort (F= 3.27; p = 0.158) for either vibration profile (Table 2.3).

Also, there was no significant difference between males and females in their reported UB

discomfort (p = 0.277) or LB discomfort (p = 0.151) scores during the LF and HF

vibration exposures. (Refer Appendix 3 for detailed interaction plot).

2.4 Discussion

2.4.1 Transmissibility

The main objectives of this research were to determine floor-to-ankle vibration

transmissibility and discomfort when exposed to two levels of FTV and to determine if

gender, foot arch type, body mass or vibration exposure frequency had an effect on floor-

to-ankle vibration transmissibility. It was hypothesized that there would be greater

71

transmissibility at the higher frequency FTV. This hypothesis was not supported as there

was greater floor-to-ankle transmissibility at the 3.15Hz-10Hz vibration exposure profile

than at the 40Hz FTV profile. Our finding appears to be in contradiction to previous

theories regarding vibration induced injury as Thompson reported a case of VIWFt, when

workers were exposed to vibration at 40Hz (Thompson et al, 2010). This may hint

towards injury risk being closely linked to exposure frequency and resonance of the foot.

Although the resonant frequency of the foot has not been reported to date, there is

evidence to suggest it might be in line with reported resonant values for the hands and

fingers, since previous research has shown similar changes in the foot as the hand when

exposed to similar vibration frequencies (Hedlund, 1989; Sakakibara et al, 1991; Hirata et

al, 1995; Sakakibara et al, 1994; Thompson et al, 2010; Choy et al, 2008). The

development of HAVS is associated with vibration exposure at a frequency range of 20-

50Hz, and more than 80Hz for the fingers (Griffin, 1990). Previous research has reported

cases of VWFt in workers exposed to FTV at or above 40Hz (Leduc et al, 2010; Hedlund,

1989; Toibana and Ishikawa, 1990). For example, workers who operate drills off raised

platforms in underground mines were exposed to vibration with a dominant frequency

between 30Hz- 40Hz and several of the workers in the study had diagnosed cases of

VWFt (Leduc et al, 2010).

Vibration attenuation at the high frequency exposure (40Hz) observed in this study may

be the result of the differences in the apparent mass or impedance of the foot in contact

with the vibration surface (Dong et al, 2005). The bio-dynamic response of the foot to

FTV is still not fully understood and further studies at a greater range of frequencies and

vibration exposure magnitudes are required. Detailed information on the bio-dynamic

72

response of the foot to FTV is important to determine interventions to attenuate vibration

and reduce the incidence of VWFt in workers exposed to FTV.

Our hypothesis that females would transmit less vibration than males was not supported.

There were no significant gender differences in floor-to-ankle vibration transmissibility at

either vibration exposure profile. Gender differences in transmissibility have received

little attention in the past. In an earlier study, Griffin and colleagues (1982) exposed 18

males and 18 female subjects to WBV between l-100Hz and found that, women had

significantly less vertical head motion at 2.5Hz and significantly more vertical head

motion at 40, 50 and 63Hz. In a separate study researchers found that females tend to

absorb more vibration power per kilogram of sitting weight. This was linked to a higher

ratio of body fat to muscle mass in females. It was stated that “fat is viscous and inelastic,

implying a high degree of damping and thus more power absorption among females”

(Lundstrom and Holmlund, 1998). Future research may consider looking at differences in

vibration transmissibility between males and females with an equal body mass index

when exposed to FTV.

Our hypothesis that there would be a significant difference in floor-to-ankle vibration

transmissibility with differences in body mass was not supported. Body mass of the

participants was thought to be important in vibration transmissibility through the foot. It

has been reported that increased coupling between the hand and the handle of hand-held

equipment during exposure to hand-arm vibration tends to increase the impedance at the

hand. Furthermore, a moderate grip force was found to be associated with greater

transmissibility than a light grip when applied on a hand held vibration tool during hand-

arm vibration exposure (Griffin, 1990). Therefore, during exposure to FTV, we

hypothesized that individuals with lower body mass would apply less contact force on the

vibration platform than individuals with greater body mass, which could lead to a

difference in vibration transmissibility. In another study by Eger et al. (2011) on the

influence of vehicle size, and haulage capacity on vibration exposure of LHD vehicle

operators, it was reported that there was significantly lower vibration exposure during

loaded haulage compared to empty haulage. Thus, there was less vibration transmitted

during the heavily loaded vehicle than when the vehicle was empty. Based on these

findings, it was assumed that there might be less vibration transmissibility in participants

with greater mass compared to lower mass participants.

We hypothesized that a high foot arch type would attenuate more vibration than the

medium and low foot arch type. This hypothesis was not supported. It has been reported

that the bio-dynamic response of the hand depends on the physical characteristics of the

hand like the hand grip and area of the hand in contact with the hand-held vibration tool

(Griffin, 1990). Health risks at the foot were believed to be associated with a similar

vibration frequency range known to lead to HAVS (Thompson et al, 2010). Similarities

between VWFt and HAVS have also been suggested from similar pathological findings in

the foot and hand when exposed to the same vibration frequency range (Hedlund, 1989;

Leduc et al, 2010; Toibana and Ishikawa, 1990; Thompson et al, 2010). Thus, foot arch

type was evaluated to determine if floor-to-ankle vibration transmissibility was dependant

on the area of the foot in contact with the vibration platform. Dong et al. has stated that

the surface area of the hand in contact with the vibration source plays a significant role in

vibration transmissibility, which is estimated through the apparent mass or mechanical

74

impedance of the hand-arm surface in contact with the vibration tool (Dong et al, 2005).

It has also been reported that increased coupling between the hand and the handle o f the

equipment tends to increase the impedance at the hand (Dong et al, 2005). This suggests

that there might be a difference in the mechanism of force distribution during composite

grip of the hand and the weight transmitted through the feet while standing. However, the

size of the anatomical structures of the hand and feet differ and might be responsible for

the differences in the impedance and vibration transmissibility in the hand and foot.

2.4.2 Discomfort

Our hypothesis regarding discomfort was not supported as there was no significant

difference between the reported discomfort and frequency of vibration exposure.

However, the participants tended to reported higher discomfort during the high frequency

vibration exposure conditions than during low frequency exposure. That being said, it is

important to note that there was a difference in the magnitude of vibration that

participants experienced during the high frequency (22.1 m/s2) and low frequency (1.1-

2m/s2) vibration conditions. Participants tended to report higher discomfort under the

higher magnitude exposure. This finding is in line with findings from Mansfield (2000)

who reported greater discomfort with higher magnitude vibration compared to lower

magnitude vibration.

Our hypothesis regarding discomfort and gender was also rejected as there was no

significant difference in reported discomfort for males or females. This finding

contradicted the results of Leduc et al. (2010) who reported lower discomfort scores for

female participants compared to male counterparts when exposed to the same level of

vibration. Furthermore, in a study to examine gender difference in subjective response to

75

WBV in different directions, while standing, it was reported that, regardless of the axis of

vibration, males reported more discomfort than females (Shibata et al, 2010).

2.5 Limitations

Earlier research has stated that a 20 second vibration exposure duration was sufficient for

participants to provide a discomfort report during seated exposure to WBV (Dickey et al,

2006). In a field study of seated WBV exposure, Grenier et al. (2010) found experienced

operators had large variability in discomfort reports and hypothesized that operators are

so habituated to high vibration levels, or biased by previous injury, that their perception

of discomfort is masked or distorted to differentiate between different stimuli, unless the

vibration is severe. Although a 20 second exposure duration was used in this study, it

might not have been long enough to enable participants to register and report discomfort

from FTV. Alternatively, participants with pervious exposure to occupational FTV or

recreational FTV (exercise platforms) might not be as sensitive to FTV. We also found

that some of the participants that had a low mass and no previous exposure to high

frequency FTV, found it more difficult to balance on the platform. Therefore, they might

have been more focused on maintaining their balance, which may have masked the

perception of vibration related discomfort. Thus, future study might consider longer

duration exposures and consider categorizing participants based on previous exposure to

FTV. Future studies might also benefit from the inclusion of experienced participants

from the mining industry for the laboratory set-up and/or a field-study in the mines.

The sample size was unequally distributed and small to determine the effect of foot arch

type on the vibration transmissibility. There were only three participants in the high foot

76

arch category, whereas six participants fell into the low and seven into the medium arch

type category. Future study with individuals equally distributed in each foot arch category

may be performed in order to determine if the area of the foot in contact with the

vibration surface influences floor-to-ankle vibration transmissibility.

Lastly, one of the identified limitations of the present study was the use of ISO 2631-1

WBV guidelines to determine the frequency-weighted r.m.s. acceleration data. Previous

researchers have suggested that measurements recorded at the feet should be done in

accordance with ISO 5349-1 guidelines as opposed to ISO 2631-1 guidelines (Thompson

et al, 2010). The ISO 5349-1, hand-arm vibration standard, may calculate a more

appropriate frequency-weighted acceleration value since the weighting curve does not

down weight higher frequency vibrations at the same rate (Thompson et al, 2010).

Furthermore, the hand and foot are structurally similar (however they vary in their size

and muscle mass) which implies they might react similarly to the vibration exposure

(Mansfield, 2005). Future research examining the characteristics and health effects of

vibration entering the body through the feet may also consider recording their

measurements and analysis using ISO 5349-1 HAV guidelines, in addition to ISO 2631-1

guidelines, until a standard, specific to FTV is standardized internationally.

2.6 Conclusion

Although previous research work has linked pathological changes in the foot with a FTV

exposure frequency of 40 Hz, this study reported less floor-to-ankle vibration

transmissibility at 40Hz, which might suggest greater absorption of vibration within the

localized tissue. Measured floor-to-ankle vibration transmissibility was greatest when

exposed to lower frequency vibration. At this stage it may be concluded that the

pathological changes in the foot may not be solely linked to the localized transmissibility

recorded at the feet when exposed to FTV.

Also, unlike HAV exposure, where the physical characteristics like surface area of the

hand in contact with the vibration tool, hand grip force, and posture of the upper

extremity, affects the vibration transmissibility (Dong et al, 2005; Griffin 1990), during

FTV, no significant relationship was found between the physical factors and vibration

transmissibility. This difference may be linked to difference in the size and function of

the physical factors in the hand and foot. Based on the present findings, it can be

concluded that foot arch type and mass of the individual and gender do not play a

significant role in floor-to-ankle vibration transmissibility.

78

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86

CHAPTER 3

EVALUATION OF VIBRATION TRANSMISSIBILITY PROPERTY AND COMFORT OF INSOLES AND BOOTS WORN BY MINE WORKERS

87

Abstract

There is limited work on foot transmitted vibration (FTV) despite evidence that prolonged

vibration exposure at the feet can lead to neurological, vascular and musculoskeletal

symptoms occurring either due to direct segmental exposure of the feet to vibration or as

a secondary complication to hand-arm vibration syndrome through the sympathetic

channel. Anecdotal evidence from workers at underground mines suggests that the use of

insoles or certain mining boots might protect the worker from the harmful effects of FTV.

Therefore, the vibration transmissibility properties of commercially available insoles and

mining boots were evaluated, along with associated comfort. Sixteen participants (eight

males and eight females) experienced four insoles and two mining boot conditions at two-

vibration levels, while standing on a low frequency (LF) vibration platform (3.15-6.3Hz)

and a high frequency (HF) vibration platform (40Hz). Vibration was recorded at the floor

and above the insole/boot at the ankle with two tri-axial accelerometers in accordance

with the ISO 2631-1 standard. The percent difference between the vertical axis (z-axis)

frequency-weighted acceleration at the ankle (Aawz) and the frequency weighted

acceleration in the z-axis entering the foot at the floor through the insole/boot barrier

(Fawz) was taken as the measure of vibration transmissibility of the insole/mining boot at

the ankle. A significant difference in vibration transmissibility of the insoles (P = 0.0001)

and the boots (P = 0.014) at LF and HF was observed with greater attenuation occurring

at HF vibration exposure. However, no significant difference was observed in the

transmissibility of different insole conditions and boot conditions. Also no significant

difference was observed in the subjective discomfort (U.B: p = 0.944, F= 17.91; L.B: p=

0.08, F= 17.91) ratings of the individual participants.

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3.1 Introduction

International Labor Office in 1977 recognized that vibration exposure is one of the latent

causes for occupational hazard in many industries (Mandal, 2006). Approximately 4-7%

of workers in Canada, the U.S and European countries are exposed to vibration that may

potentially cause health effects (Bovenzi, 1996; Bernard, 1997). Similarly, Mandal (2006)

reported increased hand-arm vibration (HAV) and whole-body vibration (WBV) risk in

Indian working at mines, due to vibration exposure. Also, in the gold mines in South

Africa, the prevalence rate of hand-arm vibration syndrome (HA VS) is estimated at 15%

(Dias et al, 2005).

Knowledge of how vibration is transmitted to and through the human body can provide

important information concerning the bio-dynamic response of the body to vibration

exposure. In the workplace, people can be exposed to vibration when standing, sitting and

in some cases when lying in contact with a vibration source (Griffin, 1998). Researchers

have reported acute and long term health effects related to vibration exposure in workers.

These include loss of visual acuity, postural stability, manual control, low back pain,

early degeneration of the spine, herniated discs, neurological, digestive disorders and

circulatory disorders (Mayton et al, 2008). WBV may also contribute to the development

of noise induced hearing loss (Seidel and Heide, 1986); circulatory disturbances such as

varicose veins; and menstrual disorders, proneness to abortion and hyperemesis gravidum

in women (Abrams, 1990 and Wasserman et al, 1997). Earlier studies have reported that

workers exposed to HAV were diagnosed with Raynaud’s phenomenon of the hand and

fingers with reduction in muscular strength and dexterity (EU guide to good practice on

HAV, 2006; Cohen et al, 1995; Bovenzi, 1998). The characteristic neurovascular and

8 9

physical changes in the hand arm system due to long-term vibration exposure are often

addressed as vibration induced white finger (VWF) and the condition is known as hand

arm vibration syndrome (HAVS) (Palmear, 1998).

The development and implementation of techniques to reduce the harmful effects of

WBV and HAV has been wisely carried out by several researchers in the past. The use of

personal protective equipment (PPE), like anti-vibration gloves and suspension seats, are

recommended to reduce harmful HAV and WBV respectively. Exposure to WBV from a

seated position and techniques to attenuate vibration by seat modifications have been

widely studied (Paddan et al, 2001; Niekerk et al, 2001; Mayton et al, 2008; Douglas et

al, 2006). Similarly, HAV exposure associated with gripping vibrating tools has been

studied in depth (ISO 5349-1; 1986) and attention has been given to the development of

anti-vibration tools and gloves to reduce HAV exposure (Jetzer et al.; 2003; Hewitt, 1998;

Dong et al, 2005; Giffin, 1990; Mansfield, 2005). However, the benefits of PPE for

workers exposed to FTV are less understood.

Workers can be exposed to FTV when standing on a surface that vibrates or when using

vibrating hand held equipment that is physically attached to a platform a worker stands on

(Eger et al, 2006). The health effects associated with such exposures and the bio-dynamic

response of the feet to FTV have received little attention. Workers can be exposed

directly or indirectly to FTV. For example, indirect exposure can occur when workers use

hand-held drills attached to platforms they stand on (Hirata et al, 2004; Leduc et al, 2011)

or directly when they stand to operate mobile equipment such as locomotives (Eger et al,

2006; Leduc et al, 2011). Neurological symptoms typically observed in the hands after

90

occupational exposure to HAV have also been seen in the feet of workers exposed to

similar vibration frequencies and accelerations (Griffin, 2008). Peripheral vascular

disorders and Raynaud’s phenomenon of the toes (vibration induced white feet) were

reported in chain saw workers (Sakakibara, 1994) and underground mine workers

(Hedlund, 1989) who were exposed to FTV while standing. Leduc et al. (2010) also

reported that two of seven miners exposed to FTV were diagnosed with VWFt in a recent

study at northern Ontario mine sites. Reportedly, both of the workers were exposed to

standing vibration through their feet and were also diagnosed with HAVS. Studies have

reported that patients with vibration white finger (VWF) are likely to complain of

coldness in their feet as well as the hands and have low skin temperature of the fingers

and toes (Sakakibara et al, 1991; Hirata et al, 1995). One of the important finding by

researchers stated that there is a relationship between pathological changes in the feet of

workers and HAVS. It was reported that workers with HAVS will likely have

neurovascular disturbances in the foot in conjunction with VWFt. Vascular changes like

thickening of the tunica media layer of the foot vessels and perivascular fibrosis etc., with

vibration white finger (VWF) (Sakakibara et al, 1995; Hashiguchi, 1994), and reduction

in the sensory nerve conduction velocity in the feet of patient with HAVS (Hirata et al,

1995), were identified in the workers. Further studies reported that these changes resulted

from the long-term repeated vasoconstriction and circulatory disturbances in the foot

resulting from the stimulation of the sympathetic branch of the autonomic nervous system

caused by HAV exposure (Hashiguchi, 1994; Sakakibara et al, 1995). Thus, these studies

suggested that changes in the feet could also result from the indirect effect of long term

vibration exposure to the hands.

However, a condition analogous to HAVS was reported recently in the feet of a worker

after prolonged exposure to segmental lower-extremity vibration (Thompson et al, 2010).

The results showed a vasomotor disturbance associated with cold sensitivity in the toes

but not in the hands of the miner who was exposed to vibration from underground bolting

machines over an 18 years career (Thompson et al, 2010). In another study, House et al.

(2010) reported that the patients exposed to segmental foot vibration had severe

vasospasm of the feet and that the changes in the feet were not necessarily

sympathetically induced and could be the direct result of segmental vibration exposure at

the feet while standing (House et al, 2010). Thus, while centrally mediated mechanisms

may contribute to vibration syndrome in the hands and feet, local pathology secondary to

direct segmental vibration exposure also plays a significant role in some cases (House et

al, 2010).

PPE like anti-vibration mats, anti-vibration insoles and boots are used in many mining

industries and other industries where workers are exposed to potentially harmful

vibrations to protect workers from the harmful effects of FTV. However, the ability of

mats, insoles and boots to attenuate FTV has not been thoroughly evaluated. Any material

can either attenuate or amplify vibration. In relation to drilling platforms, the degree of

amplification or attenuation is dependent on the structural resonances occurring in the

path of the vibration as it travels from the drill through the platform to the worker (van

Niekerk et al, 2003). If the resonant frequency of the PPE is the same as the exposed

vibration frequency, then the overall resultant vibration will be amplified as it travels

through the PPE. If this is the case, the PPE would not be suited to the application, and in

fact, would increase a worker’s injury risk (Leduc et al, 2010). Anti-vibration gloves used

92

to protect workers from HAV can attenuate vibration in the frequency spectrum ranging

from 100-1600 Hz (Griffin, 1998); however, some gloves have also been found to

amplify vibration (Mansfield, 2005). In 2010, Leduc and colleagues tested the efficacy of

three different types of mats used in the mining industry to protect workers from FTV.

The mats tested did not significantly attenuate FTV (Leduc, 2010). However, it was

reported that the mats provided the workers with a softer surface, which was less

fatiguing and more comfortable than standing on a hard concrete floor during vibration

exposure (Leduc et al, 2010). Leduc et al. used Mat Effective Amplitude Transmissibility

(MEAT) to determine the transmissibility properties of the mats. Similar to the SEAT

(Seat Effective Amplitude Transmissibility) value, which is used to evaluate the ability of

seats to attenuate vibration (Niekerk, 2003), the MEAT value was defined as the ratio of

the vibration experienced on top of the anti-vibration mat being tested and the vibration

experienced when standing directly on the vibrating floor (Niekerk, 2003; Leduc et al,

2010). It was hypothesized that the mat associated with the lowest MEAT value would

have the lowest reported discomfort following vibration exposure, although no significant

finding was reported (Leduc et al, 2010). On the other hand, Niekerk reported a positive

correlation between mean SEAT values and dynamic comfort reported by the participants

for vertical rough road stimuli (Niekerk, 2003).

Similar to anti-vibration gloves, anti-vibration insoles and mining boots are made up of

different types of materials designed to attenuate FTV and provide comfort during

prolong standing. Viscoelastic polymers like Sorbothane, Viscolas, Polyurethane foams,

ethylene vinyl acetate etc. (Whittle, 1996) are widely used by insole manufacturers, while

rigid and low compliance polymers like Kevlar are used in the manufacturing of mining

93

boots. However, their ability to attenuate FTV has yet to be proved. Viscoelastic materials

have been proved to provide useful shock attenuation during heel strike of the gait cycle

as well as redistribution of pressure beneath the foot (Whittle, 1996). On the other hand,

Kevlar like polymers comprise one of the best stiffness to mass ratios with the additional

benefit of self damping. Due to the high stiffness to mass ratio, the resonance of the low

compliant polymers naturally occur at a very high frequency. This property of polymers

like Kevlar makes them ideal to be used under high frequency vibration conditions

(Marshall Cavendish Corporation; 2003). Recently, boot manufacturers have replaced the

metallic shanks, they used previously with polymer shanks like Kevlar, to help reduce the

harmful vibrations that may enter through the feet of mine workers. The most important

factor when selecting vibration attenuating materials is their natural vibration frequency,

in order to avoid using a material whose resonant frequency is the same as the input

vibration frequency of the platform or vibrating surface (Boucher et al, 2011). Thus

selecting materials with higher resonant frequencies is ideal for manufacturing PPE for

vibration exposure.

Comfort is also an important measure to consider when determining the effectiveness of

PPE. A comfortable stimulus is defined as one where the subjects do not have to change

their activity or reduce exposure magnitude (Mansfield, 2005). Absence of nociception or

pain stimuli is often considered to contribute to a sense of comfort. However, depending

on the intensity and characteristics of vibration, a vibration stimulus might not be painful

but may produce a sense of subjective discomfort (Mansfield, 2005). In 2006, Dickey et

al. conducted a laboratory study and reported that there was no significant difference in

94

the reported discomfort between 15 second or 20 second vibration exposures, or 5 second

and 10 second rest durations (Dickey et al, 2006).

Human response to vibration is complicated by the fact that the body does not respond

equally to all frequencies. Each segment or component of the human body has its own

critical frequency, at which it oscillates to its maximum amplitude and hence causing

maximum tissue disruption. This typical frequency is identified as the resonant frequency

of the exposed body segment (Holmlund et al, 2001). Vibration frequencies in the range

of 20-50Hz are considered potentially damaging for the hand arm system and frequencies

above 80Hz for the fingers (Dong et al, 2004; Dong et al, 2010). Frequencies in the range

of 4-8Hz are harmful for the whole body (Griffin, 1990). Due to limited research on FTV

and discomfort, the critical frequency range for the feet is not known. However, during an

underground mine study, Leduc et al. (2010) reported the vibration exposure frequencies

of the underground workers exposed to vibration while standing on vibrating platforms.

Two levels of vibration frequency were identified: (a) 3.15-6.3Hz (WBV range) and (b)

31,5-40Hz (HAV range). Therefore, the vibration frequency ranges reported by Leduc et

al. (2010) were used as a reference frequency to examine the vibration attenuation

abilities of insoles and boots in the current study.

The objectives of this paper are:

a) to measure and document the vibration transmissibility properties of three

commercially available “anti-vibration” insoles when exposed to low frequency

and high frequency vibration.

95

b) to measure and document the vibration transmissibility properties of two

commercially available mining boots when exposed to low frequency and high

frequency vibration

c) to determine if there is a significant difference in the subjective discomfort scores

when participants are exposed to FTV while wearing different insoles and mining

boots.

We hypothesize that:

a) floor-to-ankle vibration transmissibility will be lower when standing on “anti­

vibration” insoles than when bare foot.

b) floor-to-ankle vibration transmissibility will be lower when wearing mining

boots than when exposed to FTV when bare foot.

c) floor-to-ankle vibration transmissibility will be lower in boots with polymer

shanks than with metallic shanks. Due to the high stiffness to mass ratio, the

resonance of the low compliant polymers naturally occur at a very high

frequency. This property of polymers makes them ideal for use under high

frequency vibration conditions (Marshall Cavendish Corporation; 2003).

d) the reported discomfort scores will be lower when wearing insoles and boots

than when exposed to FTV while bare foot.

3.2 Methodology

The research methodology was approved by Laurentian University’s Research Ethics

Board and all participants provided informed consent prior to participation. Participants

96

were ruled out for past history of concussion, lower body fracture in the last six months,

diabetes, any neurological disorders, peripheral vascular disorders, back pain and/or

sensitivity to motion sickness.

3.2.1 Participants

Sixteen participants (eight males and eight females) drawn from an university population

with mean age of 26.12 years (males) and 20.25 years (females); mean height of 171.06

cm (males) and 165.75 cm (females); mean mass of 75.01 kg (males) and 67.13 kg

(females) were recruited by a sample of convenience (Table 3.1).

97

Table 3.1: Demographic data and pre-test whole-body musculoskeletal discomfort

reported by the participants on a nine point scale (0=no discomfort; 9=maximal

discomfort)

Subject Mass (kg) Height (cm) Age (yrs) Initial Discomfort (0-9)

Male 63.6 167.5 27 0

Male 95.5 177.5 38 0

Male 82.3 171 23 0

Male 66.4 175.5 24 0

Male 86.4 173 26 0

Male 69.1 164 25 0

Male 70.9 170 23 0

Male 65.9 170 23 0

Mean (SD) 7 5 (11 .6 ) 171 (4.3) 26 (5) 0 (0 )

Female 62.5 164 21 0

Female 61.8 166 20 , 0

Female 57.3 163 19 0

Female 102.3 175 19 0

Female 50.9 161 20 0

Female 77.3 161 20 0

Female 72.7 171 20 0

Female 52.3 165 23 0

Mean(SD) 6 7 (1 7 ) 166(4 .9) 2 0 (1 .3 ) 0 (0 )

98

3.2.2 Insoles and Boots Evaluated

Three commercially available insoles (Fig. 3.1) and no insole were evaluated (INI, IN2,

IN3 and NIN). INI, IN2 and IN3 were commercially marketed as “Decode”,

“Sorbothane” and “Sofsole Airr” brand insoles, respectively. Similarly, two different

types of mining boots (MB1 and MB2), which are currently used in the mining industry

were selected for analysis (Figure 3.2). The boots differed in the material make of their

shank. MB1 came with a metal shank while MB2 had a polymer shank. The top shin

rubber portion of the left leg boot was cut out to provide sufficient room around the ankle

to mount an accelerometer at the ankle level in order to measure vibration above the boots)

(Figure 3.2).

Figure 3.1: The commercially available insoles tested. Insole 1 (INI), Insole 2 (IN2),

Insole 3 (IN3)

99

Figure 3.2: Two types of commercially available mining boots that were tested.

Mining boot 1 and 2 (MB1 and MB 2)

3.2.3 Vibration exposure

Two vibration sources were used to produce the vibration exposure profiles during the

study: (a) Low frequency vibration (LF) with dominant frequency in the range of 3.15-

6.3Hz and a frequency-weighted root mean squared acceleration of 0.7m/s2-5m/s2; (b)

High frequency (HF) vibration with dominant frequency of 40Hz and a frequency-•y

weighted root mean squared acceleration of 22.1 m/s . A custom made vibration

simulator (Laurentian University) generated the LF vibration which was selected to

replicate the dominant frequency associated with operating a locomotive or moving

mining vehicle in an underground mine (Leduc, 2010). An exercise vibration platform

100

(Power Plate North American, Inc., Irvine, CA) was used to generate the HF vibration

condition selected to simulate the vibration frequency experienced when standing on

drilling platforms or raises used in underground mining (Leduc, 2011).

3.2.4 Vibration Measurement

Two Series 2 10G MF tri-axial accelerometers (NexGen Ergonomics, Montreal, QC)

were used to collect all vibration measurements (Figure 3.3 and 3.4). The vibration data

were collected in accordance with ISO 2631-1 standard guidelines at a sampling

frequency of 500 Hz. All vibration measurements recorded by the accelerometers were

stored onto a portable datalogger, DataLOG II P3X8 (Biometrics, Gwent, UK) (Fig.

3.4b).

A ccelerom eter

Figure 3.3: Accelerometer mounted over the lateral malleolus of the left ankle above

the cut off boot

101

The accelerometers were mounted at two locations. The point of origin was on the

vibration platform and the reference point was just above the insole/mining boot on the

lateral malleolus of the ankle.

3.2.4.1 Vibration Recording at the Floor

One Series 2 10G MF tri-axial accelerometer (NexGen Ergonomics, Montreal, QC) was

mounted in the defined slot on the underside of a custom made wooden foot-board on

which participants stood (Figure 3.4c). The wooden foot-board was placed on top of the

LF and HF vibration platform so that the accelerometer was in direct contact with the

vibration surface in order to record FTV at the source. Participants were instructed to

stand with their feet placed over the wooden foot-board so that their lateral malleolus of

the ankle was aligned with the floor accelerometer.

3.2.4.2 Vibration Recording at Ankle

A second series 2 10G MF tri-axial accelerometers (NexGen Ergonomics, Montreal, QC)

was mounted on the lateral malleolus o f the left ankle (Figure 3.4a). The accelerometer

was mounted just above the insole/mining boot in order to record vibration at the ankle.

The accelerometer was secured to the bony prominence of the ankle with general

stationary velcro tape and pro-wrap (Figure 3.5). The accelerometer was aligned with the

vertical axis and calibrated each time prior to recording vibration. The angular deviation

of the accelerometer was maintained well within 15 degrees from the vertical axis as

suggested in the ISO 2631-1 standard guidelines.

102

Figure 3.4: Placement of accelerometers: a) Recording at the ankle; b) DataLOG; c)

Recording at the floor; d) Placement of wooden board and insole over vibration

simulator

3.2.5. Transmissibility Measurement

The ratio of the vibration measured by the accelerometer along the vertical (z-axis) axis at

the ankle (Figure 3.5) and the floor was used to calculate the percent vibration transmitted

from the floor through the insoles and boots while standing ( Niekerk, 2003; Leduc et al,

2010).

103

y-axis

x-axis

Figure 3.5: Axis orientation of the ankle accelerometer. The accelerometer was

aligned with the vertical (z) axis and calibrated each time prior to recording

vibration. The angular deviation of the accelerometer was maintained well within 15

degrees from the vertical axis as suggested in the ISO 2631-1 standard guidelines.

3.2.5.1 Effective Vibration Amplitude Transmissibility o f Insoles and Boots

Similar to the SEAT measurement used to evaluate the transmissibility properties of seats

(Niekerk, 2003) and the MEAT value used to evaluate the transmissibility properties of

mats (Leduc et al, 2010), insole/boot transmissibility was assessed by comparing

vibration measured at the floor to vibration measured at the ankle. Specifically, vibration

transmissibility was measured by comparing frequency-weighted acceleration in the z-

axis entering the foot (Fawz) to frequency-weighted acceleration in the z-axis at the ankle

(Aawz). The percentage difference between Aawz and Fawz was taken as a measure of

104

vibration transmissibility from the floor through the insole/boot to the ankle. Values

greater than 100% were indicative of vibration amplification through the insole/boot

condition tested, while values less than 100% were indicative of vibration attenuation

through the respective insole/boot condition. Therefore,

T (I) or T (B) = Aawz / Fawz X 100 (Transmissibility Equation) — Equation 3

Where, T (I) = Transmissibility through insole

T (B) = Transmissibility through boot

Aawz= frequency-weighted acceleration in the z-axis at the ankle

Fawz= frequency-weighted acceleration in the z-axis entering the insole/boot

3.2.6 Discomfort Score

A nine point unipolar continuous type verbal discomfort scale, with zero indicating an

absence of discomfort and nine indicating maximum discomfort, was used to record

participants’ discomfort scores (Dempsey et al, 1977). The participants were asked to

verbally report their discomfort prior to the start of the experiment session (as a baseline)

and after each 20 second vibration trial (Dickey et al, 2006). The participants were also

provided with a body chart (Appendix 1) that showed different body segments and were

instructed to point at the area of discomfort on the chart and appropriately report the level

of discomfort experienced on the nine-point scale. The discomfort was measured as upper

body (UB) discomfort and lower body (LB) discomfort. Discomfort reported in any body

area above the' pelvis (neck, upper back, shoulders, elbows, wrists, hands, and lower

back) was classified as UB discomfort, whereas discomfort to a body region below the

pelvis (buttock, thighs, knees, ankles, feet) was classified as LB discomfort. The mean

discomfort score for the UB and LB was calculated from the verbally reported discomfort

in the UB region and LB region on the nine-point discomfort scale. The discomfort scores

reported for each body region in the UB and LB were summed and a single mean value

was calculated to represent the total UB and LB discomfort for each participant.

Figure 3.6: Accelerometer placed on the lateral malleolus of the ankle and secured

by pro-wrap taping

3.2.7. Paired Comparisons

In order to determine if participants preferred one insole or boot more than the others

tested, a paired comparison (Annett, 2002) was conducted resulting in 12 paired insole

comparisons (Table 3.2) and 6 boot comparisons (Table 3.3). The order of presentation

was randomized (Appendix 4).

106

Table 3.2: Paired insole conditions for vibration testing

INSOLE CONDITION INSOLE PAIRS

INI (Insole 1) INI- IN2 INI- IN3 INI- NIN

IN2 (Insole 2) IN2- INI IN2-IN3 IN2- NIN

IN3 (Insole 3) IN3- INI IN3-IN2 IN3- NIN

NIN (No insole) NIN- INI NIN- IN2 NIN- IN3

Table 3.3: Paired boot comparisons for vibration testing

BOOT CONDITIONS BOOT PAIRS

MB 1 MB 1- MB 2

MB 2 MB 2- MB 1

NB (No Boot) NB- MB1/

NB-MB2

107

Participants were asked to step onto the selected insole (or boot) placed on either the HF

or LF vibration platform. The insole (or boot) was sized to fit the participant’s foot. Once

comfortable the participant was exposed to 20 seconds of vibration and then asked to step

down off the insole (or boot) and report their discomfort on the nine-point discomfort

scale and body chart. The second insole (or boot) in the pair was then presented to the

participant and vibration exposure lasted 20 seconds. The participant was then asked to

step off the insole (or boot) and report discomfort using the nine-point scale. After testing

each paired test, the participants were asked to indicate the insole (or boot) they preferred

based on their perceived comfort (Annett, 2002).

Participants were given a 30 second rest period between each paired comparison and a

two-minute rest period after ever three paired comparisons. It is also important to note

that the insoles were placed over the wooden footboard and secured with velcro

attachments to eliminate any vertical and horizontal displacement of the insole during

testing.

The overall vibration exposure time for the boot and insole testing was 18 minutes and 40

seconds, which was under the recommended ISO 2631-1 Health Guidance Caution Zone.

When standing on the platform, participants were reminded to stand with their knees

unlocked in order to minimize vibration transmission to the head (Caryn and Dickey,

2010; Griffin, 1990).

3.2.8 Data Analysis

The data were processed in accordance with ISO 2631-1 using Vibration Analysis Toolkit

v. 5.0 (NexGen Ergonomics, Montreal, QC, CND). Frequency-weighted root mean

108

squared acceleration was calculated (aw) and expressed in metres per second squares

(m/s ). The frequency weightings applied as listed in the ISO 2631-1 were: jc-axis =Wd;

y-axis=W<j, and z-axis=W|<. The ISO 2631-1 standard states that the vibration must be

measured according to a co-ordinate system originating at a point from which vibration is

considered to enter the human body.

3.2.9 Statistical Analysis

The dependent variables for both the insole and boot conditions were vibration

transmissibility and the reported discomfort scores; whereas gender (males; females),

vibration frequency (LF; HF), insole conditions (NIN; INI; IN2:IN3) and boot conditions

(MB1:MB2) were independent variables. To analyze the difference in the vibration

transmissibility (continuous data) and reported discomfort (continuous data) with respect

to exposed insole/boot type, frequency, gender and body mass (continuous sets of data), a

general linear model analysis of variance (GLM ANOVA) was performed with a selected

alpha level of 0.05.

3.3 Results

3.3.1 Insole Transmissibility: A multivariate analysis with six degrees o f freedom was

performed to analyze the transmissibility (y-axis) against insole type and frequency (x-

axis). We hypothesized that the floor-to-ankle vibration transmissibility would be lower

while standing on the insoles than bare foot; however, there was no significant difference

(P-value = 0.646; F= 17.91) in transmissibility across any of the insole conditions (Table

3.4). Thus, the hypothesis was not supported. There was a significant difference in floor

109

to ankle vibration transmissibility (under all insole conditions) during HF and LF (Table

3.5; Table 3.6) vibration exposures (P-value = 0.000; F= 17.91) with there being greater

transmissibility at LF FTV exposure (Figure 3.7b; Appendix 5 and 6). The interaction

plot (Figure 3.8) also shows outcomes noted during the procedure.

Table 3.4: Multivariate Analysis: GLM ANOVA- Transmissibility versus gender, frequency,

insole, mass and discomfort

Predictor Coef SE Coef T P

Constant 165.39 13.37 12.37 0.000Gender 2.985 4.692 0.64 0.526

Frequency -54.600 6.047 -9.03 0.000Insole -0.939 2.039 -0.46 0.646Mass -5.878 3.319 -1.77 0.079

*Discom UB -0.0231 0.3279 -0.07 0.944*Discom LB 0.5630 0.3199 1.76 0.081

IB = upperbody; L }= lower body

a 110-100

l=M ale9080

2= Female70

§

C

2.110-

1=IN1 100

2= IN2 90

3= IN380

704= NIN

Gender Frequency\11 w ......... ........ * \1 2 1 2

Insole Mass

• ----c--- ^

1 I 1 11 2 3 4 1 2 3

1=L.F

2= H.F

1= 50-68 Kg

2=69-86Kg

3= >87Kg

Figure 3.7: Main effect plots for the percentage vibration transmissibility versus gender, (b) frequency, (c) insole and (d) mass

110

Interaction Plot for Transm issibilityData Means

1 2 3 4 1 2 1 2 3

Figure 3.8: Interaction plot for the percentage vibration transmissibility versus

(a) gender, (b) frequency, (c) insole and (d) mass

3.3.2 Discomfort Score Associated with Insole Transmissibility

We hypothesized that subjective discomfort of the participants would be lower when

exposed to FTV when standing on insoles compared to bare foot. However, there was no

significant difference in reported UB discomfort (P-value = 0.944; F= 17.91) or LB

discomfort (P-value = 0.081; F= 17.91) scores when exposed to LF or HF FTV for any of

the insole conditions (Table 3.2). Thus the hypothesis was not supported.

Table 3.3 and 3.4 breaks down the individual transmissibility of the different insole

conditions and associated discomfort scores for male and female participants. Also,

Figure 3.9 and Figure 3.10 represent the main effect plot for UB and LB discomfort

against insole type, vibration frequency exposure and gender.

Il l

Table 3.5: Transmissibility and discomfort scores during three different insoleconditions in males following HF and LF vibration exposure

sNo

c?

Percent Diff. (LF) A a » ,/F a „ <%)

Mean Discomfort Score (LF) Percent Diff. (HF) A a „ /F a „ (%)

M ean Discomfort Score (HF)

INI IN2 IN3 UB(IN)

LB(IN)

INI IN2 IN3 UB(IN)

LB(IN)

1 2 3 1 2 3 1 2 3 1 2 3

1 93.44 95.3 93.70 0 1 2 1 3 1 134.1 125.1 1003 32 33 26 30 33 18

2 97.82 107.8 106.7 14 8.5 14 14 8.5 14 80.3 63.77 52.1 30 24 18 31 24 18

3 106.9 134.8 108.2 0 0 0 0 0 0 19.36 9.60 13.11 47 32 38 47 38 53

4 107.6 111 111.6 8 4 13 13 15 8 68.17 63.05 50.56 54 52 53 54 52 53

5 112.6 112.7 115.8 0 0 0 0 0 0 48.70 37.75 30.14 9 2 0 9 2 0

6 124.1 123.2 126.8 21 2 8 17 25 20 104.8 54.68 67.89 42 47 46 42 49 46

7 112.7 115.1 118.1 18 18 16 22 18 18.5 41.46 11.45 17.66 27 16 12 18 26 21

8 125.1 124.9 124.9 4 1 0 8 8 1 45.28 30.84 26.93 0 1 0 12 6 0

112

Table 3.6: Transmissibility and discomfort scores during three different insoleconditions in females following HF and LF vibration exposure

sNo

9

Percent DifT. (LF) A a „ /F a „ (% )

M ean Discomfort Score (LF) Percent DifT. (HF) Aa ,,,/Fa „ (%)

Mean Discomfort Score (HF)

INI IN2 1N3 l!B(IN)

LB(IN)

INI 1N2 IN3 UB(IN

LB(IN)

1 2 3 1 2 3 1 2 3 1 2 3

l 109.2 109.7 109J 0 0 0 4 0 6 56.05 48.46 47.72 48 39 41 48 25 40

2 94.2 92.69 90.03 0 0 0 0 0 0 112.1 94.99 130.5 6 2 18 25 23 19

3 87.52 88.61 86.96 18 16 16 18 16 16 26.53 29.21 40.62 17 24 24 17 24 24

4 110 98.75 104.9 0 0 0 0 0 0 59.65 55.43 58.21 22 15 20 19 21 18

5 114.4 114 113.8 0 0 0 0 0 0 131.1 125.4 119.6 37 44 32.5 30.5 28.5 39.5

6 106 110.1 108.2 0 0 0 4 1 0 15.12 22.67 18.93 21 18 15 0 0 0

7 105.7 102.9 101 0 18 17 12 25 30 77.13 74.22 68.53 45 44 36 45 44 43

8 113.1 116 114.9 0 0 0 0 0 0 117.4 82.80 51.93 35 38 32 39 29 31

113

l=M ale

2= Female

1=IN1

2= IN2

3= IN3

4= NIN

Gender Frequency 1=L.F30

2= H.F25

20

1 5 -

1 0 -

cmf 2 211

dInsole Mass30

1= 50-6825

202=69-86Kg

15

3= >87Kg

Figure 3.9: Main effect plots for LB discomfort versus- (a) gender, (b) frequency

(c) insole, (d) mass

l=M ale

2= Female

a

c

1=IN1

2= IN2

3= IN3

4= NIN

Figure 3.10: Main effect plots for UB discomfort versus- (a) gender, (b) frequency

(c) insole, (d) mass

Gender F re q u e n c y3 0 -

2 0 -

1 0 -

22 1Insole Mass

3 0 -

2 0 -

1 0 -

322 3 4 11

1=L.F

2= H.F

1= 50-68 Kg

2= 69- 86 Kg

3= >87Kg

114

3.3.3 Mining Boot Transmissibility:

We hypothesized that floor-to-ankle vibration would be lower when participants were

exposed to FTV while wearing boots than bare feet; and the boot with the polymerized

shank would attenuate vibration more than the boot with the metallic shank. However,

there was no significant difference (P-value = 0.996; F= 6.31) in floor to ankle vibration

transmissibility by boot condition (Table 3.9). Thus, the hypothesis was not supported.

However, MB1 and MB2 attenuated significantly (P-value= 0.014; F= 6.31) more

vibration at the HF exposure than LF exposure (Table 3.7 and Table 3.8; Appendix 5 &

Appendix 7). Also, refer to Figure 3.11 for main effect plot and Figure 3.12 for

interaction plot outcomes from the study.

3.3.4 Discomfort Score Associated with Boots

We hypothesized that the reported discomfort would be lower when exposed to FTV

while wearing boots compared to bare feet; however, there was no significant difference

in the reported UB discomfort (P-value = 0.78; F= 6.31) or LB discomfort (P-value =

0.15; F= 6.31) with different boot conditions (Table 3.9). The main effect plot for UB

and LB discomfort against boot type, vibration frequency and gender is presented in

Figure 3.13 and Figure 3.14.

115

Table 3.7: Transmissibility and discomfort scores for boot conditions in malesfollowing HF and LF vibration exposure

sNo

6

Percent Diff. (LF) A a « /F a ,« (%)

Mean Discomfort Score (LF) Percent Diff. (HF) A a»,/F an (%)

M ean Discomfort Score (HF)

MBI MB2 UB LB MBI MB2 UB LB

MBI MB2 MBI MB2 M BI MB2 MBI MB2

l

90.905 91.13 1 I 1 1 77.53 52.455 9 7.5 9 7.52

82.585 84.785 0 0 0 0 34.415 56 3 2 2 33

144.195 101.35 0 0 1 0 41.26 77.655 8.5 7 8.5 74

107.975 104.185 0 0 0 0 38.665 71.725 4.5 4.5 9 95

97.9 93.41 0 0 0 2 57.895 62.71 0 0.5 0 0.56

96.285 112.175 1 1.5 0 0 57.61 48.04 4.5 7.5 8 7.57

104.8 96.347 1 1 1 1 64.49 127.35 0 4.5 5 4.58

114.87 94.7350 0

0 0 30.805 124.4752 0 0 0.5

116

Table 3.8: Transmissibility and discomfort scores for boot conditions in femalesfollowing HF and LF vibration exposure

sNo.2

Percent DifT. (LF) A awl/F a „ (%)

M ean Discomfort Score (LF) Percent DifT. (HF) A a « /F a « (%)

Mean Discomfort Score (HF)

MBI MB2 UB LB MBI MB2 l!B LB

MBI MB2 MBI MB2 MBI MB2 MBI MB2

l

102.78 103.205 0 0 0 0 67.795 60.82 9 0 9 62

95.455 92.035 0 0 0 0 83.365 83.74 1 0 2 13

83.125 81.191 3 2.5 3 2.5 89.246 86.214 ' 8 5.5 8 5.54

112.22 95.145 0 0 0 0 46.175 21.41 4 2.5 5 45

109.44 111.02 0 0 0 0 151.705 76.405 2 5.5 4 5.56

105.34 104.34 0 0 0 0 97.16 94.9 6.75 5 0 07

108.37 91.64 0 0 0 0.25 42.34 84.44 7 8 7 88

106.83 113.295 0 0 0 0 111.625 66.46 4 4 7 7

l=M ale

2= Female

a

c

1=MB1

2= MB2

Table 3.9: Multivariate Analysis: GLM ANOVA- Transmissibility versus gender,

frequency, boots, mass and discomfort

Predictor Coef SE Coef T P

Constant 130.64 17.07 7.66 0.000Gender 4.731 5.620 0.84 0.403

Frequency -20.389 8.071 -2.53 0.014Boots -0.029 5.506 -0.01 0.996Mass -9.532 4.104 -2.32 0.024

Discom UB 0.488 1.741 0.28 0.780Discom LB -2.410 1.650 -1.46 0.150

1=L.F

2= H.F

b

d

1= 50-68 Kg

2= 69-86Kg

3= >87Kg

1 2 1 2 3

Figure 3.11: Main effect plots for the vibration transmissibility versus

(a) gender, (b) frequency, (c) boots and (d) mass

Gender Frequency100

90-

80-

70-c

22 11I MassBoots100

90-

80-

70

118

l=M ale

2= Female

1=MB1

2= MB2

Interaction Plot for TransmissibilityData Means

m Gender

m

Boots

Figure 3.12: Interaction plot for the vibration transmissibility versus

(a) gender, (b) frequency, (c) boots and (d) mass

1=1. F

2= H.F

b

d

1= 50- 68 Kg

2=69- 86Kg

3=>87 Kg

1 2 1 2 3

Gender Frequency

Boots

Figure 3.13: Main effect plots for UB discomfort versus- (a) gender, (b)

frequency, (c) boots and (d) mass

119

l=M ale

2= Female

a

c

1=MB1

2= MB2

Gender Frequency 1=L.F

4.82= H.F

3.6

2.4

1.2 -

22 11MassBoots

4.81= 50-

68 Kg3.62=69-86Kg

2. 4-

1.2 -

>87Kg0.01 2 1 2 3

Figure 3.14: Main effect plots for LB discomfort versus- (a) gender, (b) frequency,

(c) boots and (d) mass

3.4 Discussion

3.4.1 Transmissibility

The main objectives of the study were to measure vibration transmissibility for three

commercially available “anti-vibration” insoles and two commercially available mining

boots when exposed to LF and HF vibration and to determine participant discomfort

during vibration exposures. There was no significant difference in transmissibility for any

of the insole or boot conditions evaluated. Similarly, Leduc et al. (2010) did not find any

difference in the transmissibility of several “anti-vibration” mats tested.

In a study by Johnson (1988) which evaluated the effectiveness of shock-absorbing

insoles during normal walking, a 30 percent reduction in shock, at the foot, was achieved

with Sorbothane insoles when exposed to a shock frequency range of 10 Hz-150 Hz. One

120

of the insoles (IN 2), tested in this study was composed of Sorbothane, but this insole did

not attenuate LF or HF condition differently than any of the other insoles tested. Although

individual differences in transmissibility were not observed between the insole/boot

conditions tested, both boots attenuated vibration under the high frequency vibration

exposure condition. Since the vibration frequency that is considered to be harmful for the

feet has been closely linked to the frequency associated with HAV (Dong et al, 2004;

Dong et al, 2010; Thompson et al, 2010; Leduc et al, 2010, Hedlund, 1989), the ability of

the boots to offer some vibration attenuation at the 40 Hz frequency is positive.

Although floor-to-ankle vibration transmissibility was not significantly different between

the non insole and insole conditions, additional testing may be warranted.

Transmissibility across the foot should be examined at more locations and under a greater

range of FTV frequencies. For example, the insoles might be effective at attenuating

vibration transmitted to the toes but not through the heel pad to the ankle. Moreover, it is

possible that different areas of the foot absorb high frequency vibration/shock more

effectively than other regions, and the insole material will need to be adapted

appropriately. For example, the resonant frequency of the hand/palm has been shown to

be different than the resonant frequency of the fingers (Dong et al, 2010). Vibration

frequencies in the range of 20-50Hz are considered potentially damaging to the hand-arm

system, whereas frequencies above 80Hz are potentially harmful to the fingers (Dong et

al, 2004; Dong et al, 2010). Therefore, research is required to determine the resonant

frequency associated with different regions of the foot in order to design insoles with

material properties capable of attenuating harmful FTV frequencies.

Since the boots and the insoles act as a barrier between the vibrating surface and the foot,

they are considered personal protective equipment. However, as documented with anti­

vibration gloves, the effectiveness of the anti-vibration gloves depends on the exposed

area of the hand. Dong et al. (2005) reported that, the higher the apparent mass o f the

exposed area of the hand, the better the gloves were at attenuating vibration. Grip force

was also reported to affect the transmissibility of the anti-vibration gloves. Different

gloves have different material properties and it was found that the stiffness of some of the

material increased with the application of force, which increased vibration

transmissibility (Dong et al, 2005). Dong et al. (2005) also reported that due to the

differences in the physiological and biomechanical properties of the hand-palm and the

fingers, the effectiveness of a glove cannot be the same at both locations. Similar

differences are likely to exist for insoles when exposed to FTV. When standing, the centre

of pressure (COP) in the feet continuously changes to achieve a comfortable standing

posture (Winter, 1995). With a continuously changing COP, the transmissibility across

different pressure areas in the foot may also vary, as documented in the findings observed

during HAV studies (Dong et al, 2005). The coupling between the foot and the insole will

also vary with changing COP. Since it has been reported that increased coupling between

the hand and the handle of the equipment during HAV tends to increase the impedance at

the hand (Griffin, 1990), changes to COP during standing might also influence foot

transmissibility. Since there is limited information on the biodynamic response of the foot

when exposed to vibration, more research is warranted to determine the characteristics of

insoles and boots required to attenuate vibration at the feet. Procedures used to determine

transmissibility properties of anti-vibration gloves required to attenuate HAV, could be

adapted to evaluate the efficacy of different insoles and boots in the future.

122

3.4.2 Discomfort

There was no significant difference in the reported discomfort score across any of the

insole or boot conditions during HF or LF vibration exposure. Based on the paired

comparison findings, IN3 and MB2 were selected by the participants as the most

comfortable insole and mining boot, respectively. The material used to make an insole or

a boot is important. Some of the polymers like Kevlar have a very high resonant

frequency due to the high stiffness to mass ratio, which makes them an ideal material to

be used for vibration attenuation (Marshall Cavendish Corporation; 2003; Whittle, 1996).

However, high stiffness also makes these materials less compliant, which may not be

desirable when standing for long periods of time. Considering comfort, a worker standing

on an insole or mining boot for long periods of time may wish to have a less stiff

insole/boots in order to have more cushioning (Boucher et al, 2011). The primary role of

shoe insoles is to minimize the transmission of shock to the foot (Shiue, 1989 and 1992;

Tan and Shiue, 1991 and 1993). The mat effective amplitude transmissibility values by

Leduc et al. (2010) showed that the anti-fatigue mats were not able to attenuate FTV;

however, the mats provided the workers with a softer surface which was less fatiguing

and also increased comfort than standing on a hard concrete floor throughout the shift

(Leduc et al, 2010). Future work could involve identification of an effective boot-insole

combination capable of attenuating vibration frequencies believed to contribute to

potential health risks at the feet while still offering enough compliance to be comfortable

while standing for long periods of time. For example, an ideal combination might include

boots made of stiff polymers with less stiff and compliant insoles, such that the overall

pair is effective in attenuating FTV while maintaining standing comfort.

123

3.5 Limitations

While standing on the vibration platform during vibration trials, some of the lighter

participants were observed to lose complete contact between their foot and the insoles.

This might have changed the COP at different locations of the foot and insole and

affected transmissibility recorded at the ankle. In the future, insoles should be properly

secured to the foot or fitted inside a boot. The participants were also instructed to stand

on the vibration platform with unlocked knees to reduce the vertical transmission of the

vibration to the head and upper body (Caryn and Dickey, 2010; Griffin, 1990). However,

due to the closed chain mechanics, this also changed the angle at the ankle joint and thus

the muscles firing around the ankle joint. The ankle and knee angles were not

standardized across the participants and could have altered measured floor-to-ankle

transmissibility due to resulting changes in ankle joint stiffness. Since, knee joint angle

was not controlled; this could have also led to changes in accelerometer position with the

vertical axis. This is a major drawback as it may have affected the validity of the data

across the participants and therefore must be controlled in future research.

The vibration exposure magnitude also differed across the HF and LF exposure (LF had a

magnitude of 1.1-2 m/s2; HF had a magnitude of 22.1 m/s2). In future studies, the effect of

frequency and amplitude on FTV and discomfort should be tested separately by

controlling one of the factors.

Lastly, one of the identified limitations of the present study was the use of ISO 2631-1

WBV guidelines for the assessment of the data. Recent research has suggested that the

hand-arm vibration standards may provide a more accurate indication of the potential

health effects, which may occur locally at the feet as a result of the vibration exposure

(Thompson et al, 2010). Since the present research is one of the initial efforts to

124

determine FTV and vibration transmissibility of the insoles and boots, data were analyzed

with ISO 2631-1 WBV, as this is the currently accepted standard. However, future

research examining the characteristics of vibration entering the body through the feet

should evaluate transmissibility using both ISO 2631-1 and ISO 5349-1 frequency-

weighted data or un-weighted vibration data.

3.6 Conclusion

Although this study did not find a significant difference in floor-to-ankle transmissibility

across any of the insole conditions, this does not necessarily mean insoles are not

warranted for workers exposed to FTV. Insoles have been shown to help align body

posture and alleviate many lower extremity ailments. They can also improve standing

comfort and reduce fatigue associated with prolonged standing. The mining boots offered

some attenuation of FTV at the high frequency. Further research is required to identify an

appropriate boot-insole combination capable of attenuating harmful FTV frequencies in

order to reduce the risk of experiencing VWFt.

125

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CHAPTER 4

GENERAL DISCUSSION

4.1 Linking Previous Chapters

The symptoms of HAV have been reproduced in the foot when the foot is exposed to

similar vibration frequencies and accelerations (Griffin, 2008). Researchers have

identified vibration-induced neurological, vascular, musculoskeletal and sympathetic

disorders in the feet of workers who are exposed to FTV directly or indirectly

(Sakakibara, 1994; Hedlund, 1989; Hirata et al, 1995; Thompson et al, 2010; House et al,

2010). Researchers have also identified the physiological mechanisms leading to these

pathological conditions in the feet following direct or indirect vibration exposure

(Sakakibara et al, 1991; Hirata et al, 1995; Sakakibara et al, 1994; House et al, 2010).

However, the bio-dynamic response of the foot when exposed to vibration has not been

examined in detail. Chapter 2 examined the bio-dynamic response of the foot when

exposed to two levels of vibration. There was no gender difference in floor-to-ankle

vibration transmissibility. The results showed a slight attenuation of floor-to-ankle

transmissibility when exposed to HF FTV, thereby reducing the overall vibration

travelling to more superior body parts. However, further research is required to

understand the bio-dynamics of the foot under a larger range of exposure frequencies.

Additional research is also required to determine if foot arch type alters the bio-dynamic

response of the foot. Arch type (low, medium and high) was evaluated; however, the

number of participants in each group was low and a difference in floor-to-ankle

transmissibility was not observed.

134

In Chapter 3, the efficacy of “anti-vibration” insoles and mining boots was examined for

their ability to attenuate vibration at the feet. Commercially available insoles and mining

boots were evaluated at two different vibration frequencies commonly experienced in

underground mining (Leduc et al, 2010). The mining boots provided some attenuation at

the HF vibration exposure that is believed to increase the risk of VWFt (Thompson et al,

2010). However, no significant difference was noticed between the transmissibility o f the

different insoles. Future research is required to determine the best boot-insole

combination capable of attenuating vibration frequencies believed to contribute to the

development of VWFt.

4.2 Relevance to the Mining Industry

The insoles and the mining boots did not provide sufficient vibration attenuation to bring

the vibration level at the foot within the eight hour ISO 2631-1 health guidance caution

zone. However, the boots did provide some attenuation at the HF exposure. Therefore, the

mining boots tested in this study can be used by workers to reduce FTV when exposed to

higher frequency vibration (i.e. raise mining; jumbo drill operation; bolting). However,

more research is required to identify suitable personal protective equipment to attenuate a

broader range of FTV frequencies. Engineering solutions to reduce vibration emissions

from drills or improve the attenuation of platforms also needs to be explored.

4.3 Relevance to the Medical Industry

Physicians and health care providers should also evaluate the feet for signs of VWFt

when diagnosing HAVS (Choy et al, 2008). Moreover, physicians should be informed

that symptoms in the feet are not necessarily sympathetically induced by HAVS and

135

could be the direct result of exposure to FTV (House et al, 2010). Therefore, workers

exposed to FTV should be regularly evaluated by their health care provider for symptoms

of VWFt.

4.4 Relevance to the Insole/Mining Boot Manufacturing Industries

As mentioned in Chapter 3, the material used to manufacture insoles and boots is

important and must be capable of attenuating FTV. More research is needed to identify a

material that has the desirable stiffness to attenuate vibration at high frequencies while

still offering compliance for comfort when standing for prolonged hours (Boucher, 2011).

A boot-insole combination composed of a boot made of a stiff polymer to attenuate high

frequency vibration with an insole designed to minimize the transmission of shock to the

foot should be evaluated in future research.

4.5 Conclusion

There has been extensive research on HAV and WBV; however, the current study is the

first to attempt to document the bio-dynamic response of the foot to FTV and the first to

evaluate the transmissibility properties of insoles and mining boots. The relevance to the

medical, mining and personal protective equipment manufacturing industries has also

been provided to highlight the role each sector will need to play in order to reduce the risk

o f VWFt. The research community needs to evaluate the bio-dynamic response of the foot

to FTV under a larger range of frequencies in order to identify the resonant frequency of

the foot. The manufacturers of equipment need to develop equipment that emit less

vibration, and platforms that can attenuate FTV. Manufacturers of personal protective

equipment need to produce boots and insoles capable of attenuating FTV. Lastly, the

136

medical community needs to educate workers about the hazards associated with FTV and

they need to conduct thorough exams to rule out symptoms of VWFt in workers exposed

to HAV and FTV.

137

References

Boucher, D., Oliver, M., and Eger, T., (2011). Quantification and comparison of selected

material properties for anti-fatigue mats to investigate vibration transmission

reduction potential. Canadian Acoustics, Volume 39, Number 2, 86-87

Choy, N., & Sim, C. S. (2008). A case of Raynaud’s phenomenon of both feet in a

rock drill operator with hand-arm vibration syndrome. Korean J Occup Environ

Med, 20(2), 119-126.

EU guide to good practice on hand arm vibration; Implementation of Directive

2002/44/EC, V7.7 English 260506.doc, 2006

EU guide to good practice on whole body vibration, V6.7g English 070606.doc, 2006

EU Directive 2002/44/EC of the European Parliament and of the council of 25 June 2002

on the minimum health and safety requirements regarding the exposure of workers

to the risks arising from physical agents (vibration) (sixteenth individual directive

within the meaning of article 16(1) of directive 89/391/EEC)

Griffin, M.J., (1990). Hand-book of human vibration. London Academic Press

Hedlund, U. (1989). Raynaud’s phenomenon of fingers and toes of miners exposed to

local and whole-body vibration and cold. International Archives of Occupational

and Environmental Health, 61(7), 457-461. doi:10.1007/BF00386479

Hirata, M., Sakakibara, H., Yamada, S., Hashiguchi, T., Toibana, N., & Koshiyama, H.

(1995). Nerve conduction velocities in the lower extremities among patients with

vibration syndrome. Central European Journal of Public Health, 3 Suppl, 78-80

House, R., Jiang, D., Thompson, A., Eger, T., Krajnak, K., Sauve, J., & Schweigert, M.

(2011). Vasospasm in the feet in workers assessed for HAVS. Occupational

Medicine, 61(2), 115 -120. doi:10.1093/occmed/kqql91

International Organization for Standardization. ISO 2631: Mechanical vibration and

shock - Evaluation of human exposure to whole-body vibration - whole-body

vibration - Part 1: General Requirements. Geneva, 1997

International Organization for Standardization. ISO 5349: Mechanical vibration -

Guidelines for the measurement and the assessment o f human exposure to hand-

transmitted vibration. Geneva, 1986

Leduc, M., Eger, T., Godwin, A., Dickey, J., and House, R., (2010). Examination of

vibration characteristics for workers exposed to vibration via the feet. 3rd ACHV,

Iowa City, Iowa, l-4th June, 2010, 115-116

Leduc, M., Eger, T., Godwin, A., Dickey, J., and Oliver, M., (2011). Evaluation of

transmissibility properties of anti-fatigue mats used by workers exposed to foot-

transmitted vibration.. Canadian Acoustics, Volume 39, Number 2, 88-89

Shiue, Y.S., and Tan, T.E., (1993). A study of optimal equivalent characteristics of insole

materials. DE-Vol 56, Dynamics & Vibration of Time-Varying Systems and

Structures, ASME 1993-177-185

Shiue, Y.S., (1989). Computerized determination of shock attenuation in insole materials

using a resiliometer. Master Thesis, Memphis State University, Memphis, TN

Shiue, Y.S., (1992). Determination of optimal equivalent characteristics of shoe insole

materials. PhD Dissertation, Memphis State University, Memphis, TN

139

Tan, T.E., and Shiue, Y.S., (1991). Hybrid synthesis of mathematical model equivalent

for viscoelastic insole materials. Computational Methods and Experimental

Measurements V, Elsevier’s Science Publishing Co., Inc., New York, pp. 273-284

APPENDIX 1

Documentation for Study 1

141

CONSENT FORM

0 9 LaurentianUniversity 1|gr UniversiteLaurentienne

“Evaluation of mining boots and insoles to determine vibration transmissibility from the floor to the lower body” and “Evaluation and comparison of the Bio-dynamic response of the lower body to vibration exposure in both the genders while standing and to determine the effects of foot arch types on vibration transmissibility”

I ,_____________________________ , am interested in participating in the study on the(1) “evaluation of mining boots and insoles to determine vibration transmissibility from the floor to the lower body” and (2) “evaluation and comparison of the Bio-dynamic response of the lower body to vibration exposure in both the genders while standing and to determine the effects of foot arch types on vibration transmissibility (how vibration travels through the body)” conducted by Pulkit Singh, MHK candidate and Professor Tammy Eger, PhD, from Laurentian University (funded by the Workplace Safety and Insurance Board of Ontario & Centre for Research in Musculoskeletal Disorders). The purpose of the study is to examine the effectiveness of different types of commercially available insoles and mining boots for attenuation of the harmful vibrations that enters the body via feet. This research will also evaluate the vibration transmissibility in the lower body in both the genders by comparing vibrations recorded at the ankle and at the base of the great toe with the vibration recorded at the floor while standing on the vibration platform. Differences in the vibration transmissibility with the area of contact of the foot with the surface will also be studied during this research by prior assessment of the foot arch type.If I agree to participate, I will be randomly fitted with different pairs of mining boots and insoles. A specially designed wooden foot scale fitted with accelerometer (device to measure vibration) will be placed over the vibration platform during the standing trials. Two more accelerometers will be taped to my ankle and base of the great toe. During the study I will be asked to (I) stand on the vibration exercise platform at the University gym, and (II) stand on the vibration simulator at the School of Human Kinetics biomechanics lab. I am told that each trial will last for 20secs followed by 1 Osecs of rest period during which the mining boot and insole condition will be randomly changed. Also, I will undergo a general foot assessment session to evaluate my foot arch type and the area of my foot that is in contact with the floor. The total estimated vibration exposure during the testing will be less than 20 minutes and the testing may last approximately for two hours. I know that the vibration exposure and the duration will be in the recommended dose given by ISO standards. I will be asked few questions related to my health history and also to complete a body chart for discomfort evaluation.I have been informed that only members of the research team will have access to the data collected. My participation is strictly voluntary and I am free to withdraw from the study at any moment or refuse to participate without any penalty. I have received assurance from the researcher that all data collected will remain strictly confidential. My

142

individual results will not be reported. All collected data will be coded with a subject number and stored in a locked filing cabinet (in the Professor Eger’s office) or a password secured laptop (only members of the research team will have access to the data). After a period of 5 years paper documents collected will be shredded.I understand that I will receive no immediate benefit from my participation; however, results of the study will be used to identify an insole- boot combination capable of reducing harmful vibrations that enters the feet of workers. Also the evaluation of biodynamic response of the lower body to the vibration in both the genders will help to identify potential risks in different population types who are exposed to harmful levels of vibration on regular basis.There are two copies of this consent form; one which the researcher keeps and one that I keep.If I have any questions or concerns about the study or about being a participant, I may contact the lead researcher, Professor Tammy Eger via email teger@laurentian.ca. If I have any questions or concerns surrounding the ethical conduct of the study, I may contact the Laurentian University Research Office at 705-675-1151 ext. 3213. If I would like to receive a copy of the study results I can contact Professor Tammy Eger anytime after July 1, 2011. I agree to participate in this study.

Participant’s Signature:

Date:

Researcher’s Signature:

Date:

THANK YOU FOR YOUR PARTICIPATION.

143

Part A: Background Information

1. Have you ever sustained a head injury?________________________2. Have you had foot pain/injury or back pain/injury within the last 6 months?_______3. Do you get pain and discoloration of toes with change in temperature?________4. Do you get numbness or reduced sensations in the feet?____________5. Do you experience pins and needles sensation in the feet?___________6. Have you ever been diagnosed with diabetes?______________

If you have answered NO to the questions above, you may continue to participate in the research study. If you have answered YES to ANY of the questions; unfortunately, youwill not be able to participate in the research study due to the potential health risks causedby the vibration.

7. What is your current age? _____________

8. What is your current weight? (Lbs) _____________

9. What is your current height? (Feet/inches)__________

10. Gender:____________

11. Have you ever worked with vibration tools?__________________

12. If yes, when and for how many years?________________________

13. Did you experience any foot problems while working with vibration tools? _______

144

Part B: Discomfort

The body has been divided into fourteen different regions (right). For each body region please indicate if you feel any discomfort (ache, pain, numbness) in the region at the present time. If you have discomfort in an area, please rate the severity on the 9 point scale (0 being no discomfort and 9 being maximum discomfort).

Foot Assessment Protocol

1. Objective Assessment:

2. Foot Imprint:

a) Foot Length

b) Truncated foot length

c) Dorsum Height

d) Total area in contact (i.e A+B+C)

e) Arch Index

146

APPENDIX 2

The table below lists the vibration acceleration values (aRMS) for a prototype study

performed prior to the main testing. The study consisted of five male and five female

participants. The prototype study followed the same protocol and guidelines as adapted in

the main study. Participants were exposed to a high frequency and a low frequency

vibration profile. The table can also be referred to for the associated health risks for the

vibration values recorded at the floor and ankle level for the eight-hour exposure duration

based on the ISO 2631-1 eight hour HGCZ (0.45-0.9 m/s2). Based on the guidelines, for

exposures below the zone i.e. below 0.45 m/s health effects have not been clearly

documented; in the zone, i.e. 0.45 m/s2-0.9m/s2, cautions with respect to potential health-j

risks is indicated and lastly for the aRMS value above 0.9m/s , for eight hours duration,

health risks are likely (ISO 2631-1,1997).

The measurement units of the values in the chart are as follows:

•y• RMS acceleration is in meter per second squared (m/s )

• Dominant Frequency (DF) is in Hertz (Hz)

Note: P.P= Power-plate vibration exposure

Sim= Vibration simulator

147

Tablet: Vibration exposure details at high frequency (P.P) and low frequency (sim) vibration condition in male participants during trial prototype

SubjectNo.

aRMS(Floor)

PEAK(Floor)

D.F(Floor)

aRMS(Ankle)

PEAK(Ankle)

D.F(Ankle)

Transmissibility(Ankle)

l a (P.P) 9.4157 14.9505 31.5 3.0896 6.6817 31.5 32.81

l b (Sim) S.0133 21.4795 4 3.1702 10.2972 4 63.23

2a (P.P) 7.4631 14.9021 31.5 9.4566 21.9176 31.5 126.71

2b (P.P) 8.6146 16.4595 31.5 8.1272 15.9035 31.5 94.34

2c(Sim) 5.476 24.1406 4 5.3119 23.6123 6.3 97.0032

2d(Sim) 5.1627 25.4769 4 5.1977 27.7289 6.3 100.6

3a (P.P) 11.834 18.6803 31.5 8.1658 13.3525 31.5 69.0028

3b (P.P) 12.2357 18.5973 31.5 8.1364 12.9174 31.5 66.49

3c (Sim) 4.723 18.8097 4 1.6687 12.3483 6.3 35.33

3d (Sim) 4.5046 15.374 4 1.2208 9.7149 6.3 27.1

4a (P.P) 9.3151 16.1899 31.5 3.1237 6.8314 31.5 33.53

4b (P.P) 10.1208 16.2533 31.5 2.99 7.4929 31.5 29.54

4c (Sim) 5.976 26.9575 4 6.5185 27.3209 10 109.07

4d (Sim) 4.9633 19.5731 4 2.8258 9.9874 10 56.93

5a (P.P) 10.5727 16.362 31.5 7.0554 12.4061 31.5 66.73

5b (P.P) 9.8469 15.7352 31.5 8.1126 13.9688 31.5 82.38

5c (Sim) 1.384 3.8535 5 0.8004 2.5765 2.5 57.83

5d (Sim) 1.3575 4.0715 5 0.775 2.8097 2.5 57.09

148

Chart 2: Vibration exposure details at high frequency (P.P) and low frequency (sim) vibration condition in female participants during trial prototype

SubjectNo.

aRMS(Floor)

PEAK(Floor)

D.F(Floor)

aRMS(Ankle)

PEAK(Ankle)

D.F(Ankle)

Transmissibility(Ankle)

l a (P.P) 11.458 18.0652 31.5 7.0676 13.2441 31.5 61.68

l b (P.P) 11.4452 17.6968 31.5 7.2144 12.0803 31.5 63.03

lc (Sim) 3.4393 7.553 4 2.7527 14.4693 6.3 80.03

Id (Sim) 3.7621 7.2153 4 3.1016 14.2906 6.3 82.44

2a (P.P) 9.3733 14.3853 31.5 3.5274 7.5897 31.5 37.63

2b (P.P) 8.9025 13.6387 31.5 3.2014 6.2517 31.5 35.96

2c(Sim) 0.9076 2.406 3.15 0.5672 2.215 6.3 62.49

2d(Sim) 0.8616 2.1729 3.15 0.7665 2.9543 6.3 88.96

3a (P.P) 11.6164 18.2087 31.5 6.7405 14.2563 31.5 98.02

3b (P.P) 12.6308 21.4507 31.5 7.8131 15.3358 31.5 61.85

3c (Sim) 1.2097 3.8892 5 0.7223 2.8106 5 59.7

3d (Sim) 1.2926 4.1846 5 0.6963 3.5205 5 53.86

4a (P.P) 11.143 17.11 31.5 2.5144 5.1689 31.5 22.56

4b (P.P) 12.797 20.3783 31.5 2.0866 5.2388 31.5 16.3

4c (Sim) 1.6208 4.2255 5 0.8083 2.8916 6.3 49.87

4d (Sim) 1.8162 4.3087 5 1.0735 3.6892 6.3 59.1

5a(P.P) 10.9365 17.1799 31.5 5.5181 11.4467 31.5 50.45

5b (P.P) 10.7906 16.5837 31.5 2.959 7.69 31.5 27.42

5c (Sim) 1.3735 4.1362 5 1.2146 7.1362 2.5 88.43

5d (Sim) 1.6078 4.4887 5 1.2934 6.9289 2.5 80.44

149

Table 2a: Floor-to-ankle transmissibility and discomfort scores in males and females following H.F and L.F Vibration Exposure (Trial Prototype)

Gender Weight(Kg)

Transm.(H.F)

AaWI/F awz (%)

Mean LB Discomfort Score (H.F)

Transm.(L.F)

AaWI/FaWI(%)

Mean LB Discomfort Score (LF)

Male 74.8 33 0 63 0

Male 83.4 111 2.16 99 0

Male 61.2 68 5 31 0

Male 68 32 6 83 1.5

Male 72.5 75 0.5 58 0.5

Female 54.4 62 0 81 0

Female 81.6 37 0.16 76 0

Female 56.6 80 1.83 57 0

Female 58.9 19 0.33 54 0

Female 63.5 39 1.83 84 0.66

150

Residual Plots for TransmissibilityNormal ProbabCty Plot Versus Fits

•wto•a.

99

90

50

10

1 SO-50 -25 0 25

FBstogram6J0

«

r 3-°

“■ 13

0.0-20 20 40

40

■5 »a•mt 0K

-20

-40

• * t

40 50 60 70 80

Venus Order

ma-a■tt

-20

-402 4 6 8 1 0 1 2 14 1 6 1 8 2 0

O h H W O w O r i t r

Figure 2a: Residual Plot for Transmissibility-Trial Prototype

151

Data Means

2

\\

\■

m~- y / ~~~ -- ^

F requency XX

XX

w f -50

Figure 2b: Interaction Plot for the Transmissibility-Trial Prototype

Data Means

2 1

- is

Figure 2c: Interaction Plot for the LB Discomfort-Trial Prototype

152

APPENDIX 3

The table and statistical analysis presented below outlines the details from Chapter 2 of the main study.

153

Table 3a : Floor-to-ankle transmissibility and discomfort scores reported by malesfollowing H.F and L.F Vibration Exposure

Subject

(Male)

WeightLbs

FootArchType

Trans. (L.F)

Aawz/F awz (%)

Mean Discomfort Score (L.F)

by Body Region

Trans.(H.F)

Aawz/Fawz(%)

Mean Discomfort Score (H.F)

by Body Region

U.B L.B U.B L.B

1 63.6 Medium 93 9 13 133 48 48

2 95.5 Medium 104 18 18 89 42 42

3 82.3 Flat 107 0 0 29 53 53

4 66.4 Medium 111 30 37 95 54 54

5 86.4 Flat 110 0 0 52 16 20

6 69.1 Medium 124 25 29 88 54 54

7 70.9 Flat 112 25 25 31 31 25

8 65.9 High 121 7 14 47 0 14

154

Table 3b: Floor-to-ankle transmissibility and discomfort scores in females followingH.F and L.F Vibration Exposure

Subject

(Female)

Weight

(Lbs)

FootArchType

Trans.(L.F)

Aawz/F awz (%)

Mean Discomfort Score (L.F)

by Body Region

Trans. (H.F)

Aawz/F awz (%)

Mean Discomfort Score (H.F)

by Body Region

U.B L.B U.B L.B

1 62.5 Flat 108 0 1 72 54 45

2 61.8 Medium 89 0 0 111 4 32

3 57.3 Medium 91 18 18 27 30 30

4 102.3 Flat 111 0 0 65 23 11

5 50.9 Medium 108 0 3 111 46.5 23.5

6 77.3 High 106 0 2 27 18 0

7 72.7 Flat 99 26 36 88 31 47.5

8 52.3 High 108 0 2 96 41 43

155

sVto£

Residual Plots for Transmissibility Normal ProbaMty Plot Versus fits

99

90

90

10

12S 90-2S 0-90

90

2S0

-29

-90

• « •* *»** • •

• •• • •

• •

50 75 100HUai Valaa

125

8

>» 8 vSI 4to"■ 2

0

Histogram

Q .-40 -20 20 40

Versus Order

ma•mK -2S

-502 4 6 • 1012 14 1 6 1 8 2 02 2 2 4 2 6 3 3 0 3 2

Ofcatrvatioa Order

Figure 3a: Residual Plot for Transmissibility

156

Data Means

G ender— • — 1— 2

FMftJMh

Figure 3b: Interaction Plot for the Transmissibility

Data Means

1 2 3

■— — •-'a

A - :

*******

• - — «- —

)>

i i

i1

Mm*

, i ........I 1

Figure 3c: Interaction Plot for the UB Discomfort

157

Data Means

1 2 1 2 3 1 2 3_1___________________ « » l » ■ t_ __1

Ni

}/

_ -4r - \

\

Mhm

■

. 40 G ender12-20 — m~

-0-40 Frequency

—• — 1-20 - > 2

-0-40 Mass

1-20 — m - 2

3

httM l

Figure 3d: Interaction Plot for the LB Discomfort

APPENDIX 4

Template 1-Insole Testing

159

Subject #______________ Date:

Vibration Trial:

First Insole

Condition

DiscomfortRating

DiscomfortArea

Subjective Comfort

Rating o f the Insole

Second Insole Condition

DiscomfortRating

DiscomfortArea

la IN 1 IN 2

lb IN 2 IN 1

2a IN 1 IN 3

2b IN 3 IN 1

3a INI NIN

3b NIN IN I

2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest

4a IN2 IN3

4b IN3 IN2

5a IN2 NIN

5b NIN IN2

6a IN3 NIN

6b N IN IN3

160

Vibration Trial;

First Insole

Condition

DiscomfortRating

DiscomfortArea

Subjective Com fort Rating

o f the Insole

SecondInsole

Condition

DiscomfortRating

Discomfort Area

la IN 3 IN 1

lb IN 1 IN 3

2a IN 3 IN 2

2b IN 2 IN 3

3a IN3 NIN

3b NIN IN3

2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest

4 a IN I IN 2

4b IN2 IN I

5a INI NIN

5b NIN IN I

6a IN2 N IN

6b N IN IN2

161

Template 2-Insole Testing

162

Subject #______________ Date:

Vibration Trial:_________________

First Insole

Condition

DiscomfortRating

DiscomfortArea

Subjective Com fort Rating

o f the Insole

Second Insole Condition

DiscomfortRating

DiscomfortArea

l a IN 2 IN I

lb IN 1 IN 2

2a IN 2 IN 3

2b IN 3 IN 2

3a IN2 N IN

3b NIN IN2

2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest

4 a N IN IN I

4b IN I NIN

5a N IN IN3

5b IN3 N IN

6a INI IN3

6b IN3 IN I

163

Vibration Trial:

First Insole

Condition

DiscomfortRating

DiscomfortArea

Subjective Com fort Rating

o f the Insole

Second Insole Condition

DiscomfortRating

DiscomfortArea

la IN 3 IN 1

lb IN 1 IN 3

2a IN 3 IN 2

2b IN 2 IN 3

3a IN3 NIN

3b NIN IN3

2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest

4 a IN I IN2

4b IN2 INI

5a INI NIN

5b NIN IN I

6a IN2 NIN

6b NIN IN2

Template 3-Insole Testing

165

Subject #______________ Date:

Vibration Trial:_________________

First Insole

Condition

DiscomfortRating

DiscomfortArea

Subjective Com fort Rating o f

the Insole

Second Insole Condition

DiscomfortRating

DiscomfortArea

l a NIN IN 1

lb IN 1 N IN

2a NIN IN 2

2b IN 2 N IN

3a N IN IN 3

3b IN 3 N IN

2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest

4 a IN2 IN I

4b INI IN 2

5a IN2 IN3

5b IN3 IN2

6a IN I IN3

6b IN3 IN I

166

Vibration Trial:

First Insole

Condition

DiscomfortRating

DiscomfortArea

Subjective Com fort Rating

o f the Insole

SecondInsole

Condition

DiscomfortRating

DiscomfortArea

la IN 3 NIN

lb N IN IN 3

2 a IN 3 IN 2

2b IN 2 IN 3

3a IN I N IN

3b NIN INI

2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest 2 min Rest

4a IN3 IN I

4b IN I IN3

5a IN2 NIN

5b N IN IN2

6a INI IN2

6b IN2 IN I

APPENDIX 5- Insole and Boot Testing

168

Residual Plots for TransmissibilityItomial ProbaMHy Plot

6•uto•0.

-so so 100-100 0

Versus Rts

so■5 25aa o“ -25

-SO

—

^ til> • • • * • ••* ( '* r

40 60 00 100 HtteriVrfae

120

*»u

tfistogram Versus Order30

20

10

0-60 -40 -20 0 20 40 GO 1 1 0 2 0 3 0 « 5 D e 0 7 0 B ) 9 0 1 f l 0 1 1 0 1 2 0

Figure 5a: Residual plot for the Transmissibility of the Insole Trial

169

Data Means1 25 s .

Iaoate

\ ^ mr

100

75

50100

75

SO100

75

50

Figure 5b: Interaction plot for the Transmissibility of the Insole Trial

Data Means1 2

- 30

- 15

- 30

- 15

- 30

- IS

Gander12

Mid*

Figure 5c: Interaction plot of the UB discomfort for the Insole Trial

170

1 2 3 4

Data Means 1 2

¥

* - — 4 l

I l t M tt

y

¥

A- - - - - - - - - ^

- X

. 2D- 10

X- X

- X

X

20

U X

GertiB-12

— J k r ■

Insole1234

Oil

Frequency12

Figure 5d: Interaction plot of the LB discomfort for the Insole Trial

Residual Plots for TransmissibilityNormal ProbaMty Plot Versus Rts

999

cv■■a.

ai80-80 0 40

Histogram

20

IS

10

5

-60 -40 -20 0 20 40 CO

■B • «•-30

72 108GOFitted Vafcw

Versus Order

B-30-CO

I S 1015202530354045S0 55COOhseiyatioB Order

Figure 5e: Residual Plots for the Transmissibility of the Boot Trial

171

Data Means1 2 2 3

N m-. __

F ie^ M cy__ -a

—X

\■

to o ts

100 G ender1275 - m -

SD

100 Frequency— $ — 1

75 2

50

100 Bocfc1

75 —■ - 2

SO

Figure 5f: Interaction plot for the Transmissibility of the Boot Trial

Data Means1 2

Gender12

Frequency1

Boots12

Figure 5g: Interaction plot of the UB discomfort for the Boot Trial

172

Data Means

1 2

— ■ -

G ender12

- m -

Frequency12

- m -

Boob12

Figure 5h: Interaction plot of the LB discomfort for the Boot Trial

173

APPENDIX 6

The Tables below lists the vibration acceleration values (aRMS) of all the participants

recorded at the vibration platform and at the ankle level with other important details

during the insole trials at the high frequency and low frequency vibration profile. The

table can also be refererenced for the associated health risks for the vibration values

recorded at the floor and ankle level for the eight-hour exposure duration based on the

ISO 2631-1 HGCZ guidelines. According to the ISO 2631-1 for the WBV, HGCZ for

eight hour duration lies in the vibration frequency range of 0.45-0.9 m/s . Based on the

guidelines, for exposures below the zone i.e. below 0.45 m/s2, health effects have not

2 2been clearly documented; in the zone i.e. 0.45 m/s -0.9m/s , cautions with respect to

potential health risks is indicated and lastly for the aRMS value above 0.9m/s2, for eight

hours duration, health risks are likely (ISO 2631-1, 1997).

The measurement units of the values in the chart are as follows:

• RMS acceleration is in meters per second squared (m/s2)

• Dominant Frequency (DF) is in Hertz (Hz)

Subject 1 - Power-plate data

S. No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

Trans INSOLE Ankle

l a 1 IN 3 12.4401 24.6357 40 15.2233 36.6442 40 122.37

l a 2 IN I 19.2021 41.3234 40 26.5553 63.0399 40 138.29

1 b 1 IN I 11.7847 22.8652 40 13.1831 28.816 40 111.87

1 b 2 IN 3 27.9843 53.3883 40 23.5986 41.338 40 84.33

2 a 1 IN 3 13.41S3 28.8412 40 13.4412 32.3011 40 100.19

2 a 2 IN 2 16.3094 42.9782 40 21.8186 47.9306 40 133.78

2 b 1 IN 2 26.8691 51.5431 40 26.9152 58.0839 40 100.17

2 b 2 IN 3 24.6273 42.0486 40 26.3848 52.418 40 107.14

3 a 1 IN 3 28.3753 50.3424 40 28.1723 60.4846 40 99.28

3 a 2 NIN 21.4041 44.5535 40 28.7586 59.6339 40 134.36

3 b 1 NIN 14.6776 29.7274 40 26.7338 52.0819 40 182.14

3 b 2 IN 3 28.1312 51.9472 40 24.9175 56.0735 40 88.58

4 a 1 IN I 18.4422 35.014 40 37.3221 68.8508 40 202.37

4 a 2 IN 2 16.404 35.2094 40 32.0901 70.0613 40 195.62

4 b l IN 2 17.4138 41.0386 40 18.3199 53.3937 40 105.20

4 b 2 IN I 28.804 48.2 40 33.7787 64.623 40 117.27

5 a 1 IN I 26.4034 51.3382 40 31.1023 56.3363 40 117.80

5 a 2 NIN 12.5607 25.6741 40 18.4052 36.6113 40 146.53

5 b 1 NIN 28.6718 56.004 40 33.2814 57.3824 40 116.08

5 b 2 IN I 30.5912 54.8387 40 35.8912 67.0864 40 117.33

6 a 1 IN 2 29.3816 56.6299 40 26.5572 51.9644 40 90.39

6 a 2 NIN 26.0634 46.7276 40 27.175 49.5586 40 104.26

6 b 1 NIN 26.6753 51.4116 40 30.893 65.2853 40 115.81

6 b 2 IN 2 29.5639 50.5636 40 37.238 65.2953 40 125.96

Subject 1 - Vibration simulator data

S.NO.InsoleType aR.M.S noor PEAK Floor

D.FFloor

aR.M.SAnklo

PEAKAnkle

D.FAnUe

TransINSOLE

AnU*

l a 1 IN I 1.8159 5.2201 4 1.66 5.215 4 91.41

l a 2 IN 2 1.7142 5.5373 4 1.6047 5.435 4 93.61

1 b 1 IN 2 1.7357 5.2638 4 1.6042 5.2794 4 92.42

l b 2 IN I 1.785 6.5922 4 1.6507 5.5618 4 92.48

2 a 1 IN I 1.7871 5.3441 4 1.5896 5.081 4 88.95

2 a 2 IN 3 1.8747 5.0915 4 1.7895 5.0674 4 95.46

2 b 1 IN 3 1.9775 6.4302 4 1.7256 4.9302 4 87.26

2 b 2 IN I 2.007 5.2079 4 1.8829 5.9626 4 93.82

3 a l IN I 2.0074 5.8247 4 1.9884 6.3555 4 99.05

3 a 2 NIN 1.9768 5.9735 4 1.8256 5.5279 4 92.35

3 b 1 NIN 1.9728 5.6705 4 1.8564 5.7604 4 94.10

3 b 2 IN I 1.8701 5.6604 4 1.776 5.6551 4 94.97

4 a 1 IN 2 1.8016 5.8412 4 1.6756 5.3622 4 93.01

4 a 2 IN 3 1.845 5.7531 4 1.8082 5.6438 4 98.01

4 b l IN 3 1.7181 5.3088 4 1.655 5.1572 4 96.33

4 b 2 IN 2 1.8412 5.8391 4 1.7631 5.4455 4 95.76

5 a 1 IN 2 1.8884 6.182 4 1.866 5.6291 4 98.81

S a 2 NIN 1.7988 4.3797 4 1.7213 5.5655 4 95.69

5 b 1 NIN 2.0088 5.773 4 1.8955 5.9762 4 94.36

5 b 2 IN 2 1.9562 5.3241 4 1.9243 6.0753 4 98.37

6 a 1 IN 3 1.8893 5.6807 4 1.8236 5.6467 4 96.52

6 a 2 NIN 2.417 5.8932 4 2.2267 6.3851 4 92.13

6 b 1 NIN 2.6179 7.1371 5 2.3608 5.9922 5 90.18

6 b 2 IN 3 2.3902 6.3156 4 2.1196 5.9144 4 88.68

Subject 2 - Power-plate data

S.No.InsoleType aR.M.S Floor

PEAKFloor D .F Floor

aR.M.SAnkle

PEAKAnkle D .F MU(

TransINSOLE

Ankle

l a 1 IN 2 13.1468 28.0036 40 8.1869 16.3953 40 62.27

l a 2 IN I 16.7894 34.8194 40 16.0469 30.9253 40 95.58

l b l IN I 14.5415 31.0439 40 10.4866 27.5013 40 72.11

l b 2 IN 2 21.392 34.5093 40 12.5081 20.4954 40 58.47

2 a 1 IN 2 7.7603 16.1578 40 4.7384 8.8597 40 61.06

2 a 2 IN 3 12.0019 22.1038 40 7.5767 15.9509 40 63.13

2 b 1 IN 3 19.8249 33.3774 40 9 17.7091 40 46.55

2 b 2 IN 2 15.0084 31.7951 40 10.4451 21.0582 40 69.60

3 a 1 IN 2 8.8942 18.1439 40 5.6158 11.4449 40 63.14

3 a 2 NIN 5.6522 12.4286 40 4.9904 8.8488 40 88.29

3 b 1 NIN 6.7161 13.0834 40 6.8144 12.9667 40 101.46

3 b 2 IN 2 8.2858 16.1678 40 5.6455 10.7961 40 68.13

4 a l NIN 13.2739 26.787 40 10.2799 23.1996 40 77.44

4 a 2 IN I 11.5492 23.1459 40 7.5802 18.3909 40 65.63

4 b 1 IN I 17.9358 32.7143 40 12.5824 24.9598 40 70.15

4 b 2 NIN 8.7806 18.2831 40 6.2577 13.2992 40 71.27

S a l NIN 17.8992 34.1725 40 14.4427 24.2521 40 80.69

5 a 2 IN 3 19.3772 37.0587 40 10.3717 19.3276 40 53.53

S b l IN 3 11.7019 24.1902 40 6.1115 10.0404 40 52.23

5 b 2 NIN 9.5481 21.7344 40 10.7971 21.9416 40 113.08

6 a 1 IN I 7.9055 16.3432 40 6.8419 13.7782 40 86.55

6 a 2 IN 3 21.0185 39.6986 40 8.2276 14.9034 40 39.14

6 b 1 IN 3 14.1713 28.8621 40 8.2294 16.3529 40 58.07

6 b 2 IN I 15.2012 27.7609 40 13.9578 24.0996 40 91.82

Subject 2 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle PEAK Ankle

D.FAnkle

Trans INSOLEAnkle

1 a 1 IN 3 1.3714 4.2645 4 1.44 2.7817 4 105.00

1 a 2 IN 1 1.3162 4.7735 4 1.2493 3.1371 4,5 94.92

1 b 1 IN 1 1.094 3.4074 4 1.1864 2.492 5 108.45

1 b 2 IN 3 1.1027 3.2401 4 1.1919 2.5977 5 108.09

2 a 1 IN 3 1.1049 3.6552 4 1.1803 2.4406 5 106.82

2 a 2 IN 2 1.1149 3.5561 4 1.2295 2.6686 5 110.28

2 b l IN 2 1.0566 3.3295 4 1.1685 2.5231 5 110.59

2 b 2 IN 3 1.1605 4.8828 4 1.2568 2.652 5 108.30

3 a 1 IN 3 1.1285 3.6501 4 1.2217 2.6949 5 108.26

3 a 2 NIN 1.1919 3.415 4 1.2261 2.5855 5 102.87

3 b 1 NIN 1.1375 3.1344 4 1.2006 2.6069 5 105.55

3 b 2 IN 3 1.1668 3.4817 4 1.2107 2.7126 5 103.76

4 a 1 IN 1 1.667 2.9838 4 1.2418 2.5933 5 74.49

4 a 2 IN 2 1.1861 3.1864 4 1.2723 2.6019 5 107.27

4 b l IN 2 1.2033 3.6849 4 1.2367 2.379 5 102.78

4 b 2 IN 1 1.2618 4.3666 4 1.2962 2.7752 4,5 102.73

5 a 1 IN 1 1.2195 4.1304 4 1.2744 2.7247 5 104.50

5 a 2 NIN 1.185 3.9926 4 1.2335 2.5738 5 104.09

5 b 1 NIN 1.1776 3.7163 4 1.2534 2.7287 5 106.44

5 b 2 IN I 1.2346 4.3258 1.2576 2.7451 5 101.86

6 a l IN 2 1.1145 2.8014 4 1.2073 2.5414 5 108.33

6 a 2 NIN 1.2133 2.9023 4 1.2527 2.602 5 103.25

6 b 1 NIN 1.1742 3.6043 4 1.2194 2.6422 5 103.85

6 b 2 IN 2 1.1612 3.2519 4 1.2553 2.5749 5 108.10

Subject 3 - Power-plate data

S.No.InsoleType

aR.M.SFloor peak Floor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransINSOLE

Ankle

l a 1 IN 3 27.976 46.8247 40 10.2927 23.7065 40 36.79

l a 2 NIN 29.0081 48.6744 40 17.8615 30.4429 40 61.57

1 b 1 NIN 15.0002 30.7367 40 13.6337 27.5514 40 90.89

1 b 2 IN 3 11.2321 20.7545 40 5.9806 12.4232 40 53.25

2 a 1 IN 3 21.223 41.4051 40 13.1892 30.3127 40 62.15

2 a 2 IN 2 26.9404 47.2678 40 16.2678 27.6826 40 60.38

2 b 1 IN 2 29.728 47.1445 40 9.3108 18.2625 40 31.32

2 b 2 IN 3 13.0635 24.9185 40 6.3522 13.3516 40 48.63

3 a 1 IN 1 22.5419 45.4556 40 14.2625 27.7124 40 63.27

3 a 2 NIN 13.8459 33.5806 40 16.6933 29.8796 40 120.56

3 b 1 NIN 22.7216 45.6005 40 16.1512 31.8086 40 71.08

3 b 2 IN 1 22.0319 49.6369 40 14.8801 27.8208 40 67.54

4 a 1 IN 3 25.6136 48.4644 40 13.6932 25.2175 40 53.46

4 a 2 IN 1 15.2751 31.0764 40 6.0536 10.836 40 39.63

4 b 1 IN 1 27.6007 47.3791 40 12.6675 24.9032 40 45.90

4 b 2 IN 3 28.7208 47.8694 40 9.2146 17.8523 40 32.08

5 a 1 IN 2 25.2866 44.2236 40 12.1127 24.9547 40 47.90

5 a 2 NIN 24.9575 47.5838 40 14.7613 28.6901 40 59.15

5 b 1 NIN 22.5444 36.8723 40 6.803 19.9311 40 30.18

5 b 2 IN 2 26.3024 49.4157 40 13.6091 26.8292 40 51.74

6 a 1 IN 1 25.3746 46.238 40 14.0657 27.2236 40 55.43

6 a 2 IN 2 27.7513 52.4293 40 15.2697 26.3397 40 55.02

6 b 1 IN 2 26.3835 51.7062 40 11.7213 22.8159 40 44.43

6 b 2 IN I 26.3153 51.1208 40 16.9877 29.6934 40 64.55

Subject 3 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor PEAK n o o ,

D.FFloor

aR.M.SAnkle PEAK *.«.

D.FAnkle

TransINSOLE

Anklt

1 a 1 NIN 1.414 3.5579 4 1.5596 3.7224 4 110.30

1 a 2 IN I 1.4723 3.6201 4 1.6117 4.0079 4 109.47

l b l IN I 1.4938 4.4587 4 1.5975 4.0583 4 106.94

1 b 2 NIN 1.4052 3.5569 4 1.551 3.7918 4 110.38

2 a 1 NIN 1.4314 3.4647 4 1.5819 3.8743 4 110.51

2 a 2 IN 2 1.4473 3.6909 4 1.5885 4.2165 4 109.76

2 b 1 IN 2 1.5023 3.724 4 1.6322 4.0493 4 108.65

2 b 2 NIN 1.4943 3.9778 4 1.5568 3.8458 4 104.18

3 a 1 NIN 1.5385 3.8729 4 1.5788 3.7753 4 102.62

3 a 2 IN 3 1.4815 4.0328 4 1.5511 3.9028 4 104.70

3 b 1 IN 3 1.5084 3.6785 4 1.5995 3.9653 4 106.04

3 b 2 NIN 1.4866 3.6579 4 1.5989 3.962 4 107.55

4 a 1 IN 2 1.5729 4.4326 4 1.775 4.3313 4 112.85

4 a 2 IN I 1.5214 4.0847 4 1.6741 3.8862 4 110.04

4 b 1 IN I 1.5568 3.8138 4 1.7056 4.0315 4 109.56

4 b 2 IN 2 1.5479 3.8618 4 1.6756 4.0462 4 108.25

5 a l IN 2 1.5939 4.239 4 1.7117 3.9575 4 107.39

5 a 2 IN 3 1.5475 4.177 4 1.7155 4.0041 4 110.86

S b l IN 3 1.5504 3.7689 4 1.7281 4.1123 4 111.46

5 b 2 IN 2 1.6209 3.981 4 1.8062 4.2208 4 111.43

6 a 1 IN I 1.5448 4.0083 4 1.7096 4.0555 4 110.67

6 a 2 IN 3 1.9712 5.0534 5 2.216 4.5061 5 112.42

6 b 1 IN 3 1.9243 5.0972 5 2.1247 4.3709 5 110.41

6 b 2 IN I 2.0714 4.6854 5 2.2517 4.8736 5 108.70

Subject 4— Power-piate data

S.NO.InsoleType

aR.IWLSFloor PEAK Ftoo,

D.FFloor

aR.M.SAnkle p e a k ***

D.FAnkle

Trans INSOLE M

l a 1 IN 3 31.5499 54.6684 40 30.3549 51.1571 40 96.21

1 a 2 IN I 20.1446 40.8199 40 35.2851 62.7976 40 175.16

l b l IN I 26.1637 54.9403 40 26.035 48.223 40 99.51

1 b 2 IN 3 20.2518 35.592 40 31.8161 55.5275 40 157.10

2 a 1 IN 3 18.8071 35.8285 40 42.0092 81.7144 40 223.37

2 a 2 IN 2 28.8182 48.2216 40 16.4758 36.8573 40 57.17

2 b 1 IN 2 32.5354 51.4013 40 27.4031 41.8783 40 84.23

2 b 2 IN 3 31.0803 56.6906 40 29.5553 52.0842 40 95.09

3 a 1 IN 3 13.8527 24.2749 40 10.0743 20.365 40 72.72

3 a 2 NIN 30.8919 48.6154 40 29.0214 45.5037 40 93.95

3 b 1 NIN 24.9223 48.3829 40 35.6606 65.1214 40 143.09

3 b 2 IN 3 12.959 21.2853 40 17.9592 30.9067 40 138.58

4 a 1 IN I 30.1483 54.425 40 37.2896 60.269 40 123.69

4 a 2 IN 2 31.6155 54.363 40 34.2242 60.513 40 108.25

4 b l IN 2 32.7428 50.4396 40 34.0597 55.5765 40 104.02

4 b 2 IN I 32.7557 52.1603 40 33.4542 49.1886 40 102.13

5 a 1 IN I 33.4403 62.5925 40 29.2307 45.6429 40 87.41

5 a 2 NIN 29.6974 55.1554 40 33.2058 57.9392 40 111.81

5 b 1 NIN 32.3393 49.0115 40 35.0363 56.6472 40 108.34

5 b 2 IN I 30.8201 55.8547 40 26.1515 53.079 40 84.85

6 a 1 IN 2 30.2474 55.1575 40 32.6833 68.0029 40 108.05

6 a 2 NIN 28.2755 50.5758 40 33.1526 56.9675 40 117.25

6 b 1 NIN 12.8192 34.8459 40 11.7214 25.2976 40 91.44

6 b 2 IN 2 31.6155 54.363 40 34.2242 60.513 40 108.25

181

Subject 4 - Vibration simulator data

S.NO.InsoleType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnkle PEAK ami.

D.FM M t

Trans INSOLE a m .

1 a 1 IN I 1.6858 4.0459 4 1.6078 3.8006 4 95.37

1 a 2 IN 2 1.7S13 4.3528 4 1.7136 4.2243 4 97.85

l b l IN 2 1.8329 4.8577 4 1.7937 4.4079 4 97.86

l b 2 IN I 1.8788 4.2623 4 1.7706 4.5615 4 94.24

2 a 1 IN I 1.9049 5.6115 4 1.8514 4.8316 4 97.19

2 a 2 IN 3 1.9196 4.5843 4 1.7716 4.5723 4 92.29

2 b 1 IN 3 1.8086 3.9711 4 1.6303 3.7991 4 90.14

2 b 2 IN I 2.1691 4.9999 4 1.8836 4.5175 4 86.84

3 a X IN I 1.8027 4.8078 4 1.8321 4.5911 4 101.63

3 a 2 NIN 2.669 6.8968 4 2.2002 5.7265 4 82.44

3 b 1 NIN 2.1574 5.7586 4 2.05 5.3605 4 95.02

3 b 2 IN I 2.1887 5.8064 4 1.9694 5.5115 4 89.98

4 a 1 IN 2 1.9591 4.1833 4 1.8194 5.3141 4 92.87

4 a 2 IN 3 1.9566 4.4429 4 1.8356 4.4792 4 93.82

4 b l IN 3 2.0457 4.8153 4 1.9114 4.0949 4 93.44

4 b 2 IN 2 2.0321 4.7016 4 1.8246 4.5988 4 89.79

5 a 1 IN 2 1.8365 5.4714 4 1.6441 4.2694 4 89.52

5 a 2 NIN 2.4014 6.8479 4 2.1051 5.1436 4 87.66

5 b 1 NIN 2.2314 5.8039 4 1.9895 4.8464 4 89.16

5 b 2 IN 2 2.0482 4.7714 4 1.808 4.1046 4 88.27

6 a 1 IN 3 2.1639 5.0888 4 1.8296 4.1395 4 84.55

6 a 2 NIN 2.2466 6.0779 4 1.9926 5.264 4 88.69

6 b 1 NIN 2.271 5.5199 4 2.0462 4.8416 4 90.10

6 b 2 IN 3 2.0207 4.3964 4 1.7375 3.961 4 85.99

182

Subject 5 - Power-plate data

S.No.InsoleType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnkle PEAK A nkk D.F AnUe

TransINSOLE

l a l IN2 32.0321 52.6201 40 4.2804 10.4265 40 13.3628454

la2 INI 29.3371 52.976 40 7.7788 13.3439 40 26.51523157

l b l INI 14.8495 36.2893 40 3.9291 10.975 40 26.45947675

lb2 IN2 25.6303 44.0062 40 7.1506 12.795 40 27.89901016

2a 1 IN2 29.5247 51.7477 40 9.8271 20.4316 40 33.28433481

2a2 IN3 13.8769 35.2312 40 8.4068 20.5577 40 60.58125374

2 b l IN3 30.2489 52.8861 40 11.2119 22.705 40 37.06548007

2b2 IN2 28.74 50.4002 40 10.0095 19.2484 40 34.82776618

3 a l IN2 32.593 55.5953 40 10.3444 17.6635 40 31.73810327

3a2 NIN 30.0528 50.9638 40 9.9194 19.2892 40 33.00657509

3b 1 NIN 30.143 51.3311 40 9.4982 17.9894 40 31.51046678

3b2 IN2 29.3289 46.5968 40 10.0254 20.7737 40 34.18266624

4a 1 NIN 14.8014 39.6517 40 1.9382 4.694 40 13.09470726

4a 2 INI 12.3807 27.5681 40 2.1906 5.4919 40 17.69366837

4 b l INI 29.5845 47.4689 40 4.4024 10.038 40 14.88076527

4b2 NIN 30.7123 50.0008 40 7.7192 16.4152 40 25.13390401

5a 1 NIN 29.5197 53.0855 40 9.4756 19.0786 40 32.0992422

5a 2 IN3 29.7701 53.8481 40 9.8943 17.6169 40 33.23569622

5b l IN3 30.4625 50.6833 40 11.2301 23.0612 40 36.86532622

5b2 NIN 27.0886 50.4189 40 7.866 18.4254 40 29.03804552

6a 1 INI 31.0579 50.7543 40 9.0928 16.1935 40 29.27693115

6a2 IN3 28.8734 49.8172 40 12.6735 24.1937 40 43.89334128

6 b l IN3 27.5987 50.998 40 8.8661 17.101 40 32.12506386

6b2 INI 28.5696 50.4618 40 12.6826 24.5114 40 44.39194108

183

Subject 5 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle p e a k ***

D.FAnkle

Trans INSOLE A uk*

l a l IN3 1.6336 4.7096 4 1.3682 3.7345 4 83.75367287

la2 INI 1.6S49 4.9402 4 1.42 3.7133 4 85.80578887

l b l INI 1.6046 4.7466 4 1.4315 3.8747 4 89.21226474

lb2 IN3 1.4635 4.2161 4 1.2376 3.309 4 84.56440041

2a 1 IN3 1.5352 4.5256 4 1.2642 3.3292 4 82.34757686

2a2 IN2 1.5005 4.8099 4 1.2926 3.6767 4 86.14461846

2 b l IN2 1.455 3.7918 4 1.3167 3.4988 4 90.49484536

2b2 IN3 1.4381 3.8798 4 1.2883 3.5598 4 89.5834782

3 a l IN3 1.4125 4.0738 4 1.3097 3.3873 4 92.72212389

3a2 NIN 1.4799 3.9174 4 1.3628 3.7572 4 92.0873032

3b l NIN 1.481 4.0586 4 1.3606 3.7239 4 91.87035787

3b2 IN3 1.3813 3.7403 4 1.227 3.4183 4 88.82936364

4 a l INI 1.67 4.0661 4 1.3738 3.1872 4 82.26347305

4a2 IN2 1.5629 4.6074 4 1.3045 2.9597 4 83.46663254

4 b l IN2 1.4848 4.0917 4 1.2861 3.2725 4 86.61772629

4b2 INI 1.5639 4.1676 4 1.3591 3.3832 4 86.90453354

5 a l INI 1.5869 4.3594 4 1.387 3.4085 4 87.40311299

5a2 NIN 1.4699 3.7083 4 1.4066 3.677 4 95.6935846

5 b l NIN 1.6164 4.1566 4 1.5522 4.6317 4 96.02821084

5b2 INI 1.6025 4.726 4 1.4991 3.2418 4 93.5475819

6a 1 IN2 1.4879 4.3704 4 1.411 3.2493 4 94.83164191

6a2 NIN 1.7454 4.8344 4 1.5316 3.5295 4 87.75065887

6 b l NIN 1.7145 4.2221 4 1.4486 3.6331 4 84.49110528

6b2 IN2 1.5313 4.8756 4 1.3805 3.3805 4 90.1521583

Subject 6 - Power-plate data

S.No.InsoleType aR.M.S Floor P E A K f t o o ,

D.FFloor

aR.M.SAnkle PEAK Xekle

D.FAnkle

Trans INSOLEAnkle

l a 1 IN 3 13.6703 33.3577 40 1.5783 5.8882 40 11.55

l a 2 NIN 13.2475 28.3076 40 6.571 11.5524 40 49.60

1 b 1 NIN 18.7394 38.9561 40 5.0325 10.3548 40 26.86

1 b 2 IN 3 28.046 46.7328 40 3.5093 7.1924 40 12.51

2 a 1 IN 3 27.5781 48.6346 40 3.7272 9.2551 40 13.52

2 a 2 IN 2 24.0522 43.7917 40 2.7896 5.7769 40 11.60

2 b 1 IN 2 27^6803 52.0623 40 2.939 6.929 40 10.62

2 b 2 IN 3 27.9671 46.8267 40 3.9393 8.6523 40 14.09

3 a 1 IN I 23.7242 44.9116 40 4.6102 10.1019 40 19.43

3 a 2 NIN 22.4104 44.8938 40 6.9114 13.445 40 30.84

3 b 1 NIN 23.0798 47.3048 40 6.2909 15.5591 40 27.26

3 b 2 IN I 8.9414 15.903 40 2.4302 5.3415 40 27.18

4 a l IN 3 27.8547 54.3697 40 3.5672 7.5142 40 12.81

4 a 2 IN I 28.7386 49.275 40 5.0326 10.9972 40 17.51

4 b 1 IN I 27.8683 50.7918 40 5.3146 10.9039 40 19.07

4 b 2 IN 3 28.5687 51.1842 40 4.0706 8.7247 40 14.25

5 a 1 IN 2 29.5882 54.3159 40 2.8502 5.9425 40 9.63

S a 2 NIN 29.2271 51.8118 40 5.7187 9.6844 40 19.57

5 b 1 NIN 27.764 53.9057 40 5.2684 8.7391 40 18.98

5 b 2 IN 2 29.3107 56.2922 40 1.8805 4.663 40 6.42

6 a 1 IN I 28.7731 54.0334 40 4.6197 9.4327 40 16.06

6 a 2 IN 2 30.7143 54.9169 40 2.0335 4.8488 40 6.62

6 b 1 IN 2 27.0575 51.3509 40 3.4548 9.0363 40 12.77

6 b 2 IN I 28.0931 53.9358 40 4.7619 9.9793 40 16.95

Subject 6 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnkfc PEAK A nU .

D.FAnfcte

TransINSOLE

1 a 1 NIN 1.2472 3.3025 4 1.2843 3.3904 4 102.97

1 a 2 IN I 1.2317 3.5 4 1.3805 4.7305 4 112.08

1 b 1 IN I 1.2272 3.3835 4 1.368 4.6097 4 111.47

1 b 2 NIN 1.1863 3.5991 4 1.3333 4.5993 4 112.39

2 a 1 NIN 1.1664 3.1952 4 1.3364 4.3423 4 114.57

2 a 2 IN 2 1.2543 3.1807 4 3.3614 4.0133 4 267.99

2 b 1 IN 2 1.2042 3.4053 4 1.2862 3.6766 4 106.81

2 b 2 NIN 1.2345 3.6301 4 1.2717 3.7462 4 103.01

3 a 1 NIN 1.2341 3.3055 4 1.2631 3.5295 4 102.35

3 a 2 IN 3 1.1716 3.4597 4 1.2938 3.3623 4 110.43

3 b l IN 3 1.2364 3.4496 4 1.3327 3.7538 4 107.79

3 b 2 NIN 1.2131 3.1901 4 1.3096 3.9467 4 107.95

4 a 1 IN 2 1.2317 3.322 4 1.3494 3.9797 4 109.56

4 a 2 IN I 1.2243 3.2995 4 1.3137 4.0084 4 107.30

4 b 1 IN I 1.2328 3.5394 4 1.28 3.6445 4 103.83

4 b 2 IN 2 1.2517 3.9185 4 1.3653 4.6402 4 109.08

5 a 1 IN 2 1.217 3.6456 4 1.3091 3.927 4 107.57

5 a 2 IN 3 1.2068 3.6596 4 1.304 3.3715 4 108.05

5 b 1 IN 3 1.2406 3.2838 4 1.3371 3.4588 4 107.78

5 b 2 IN 2 1.2868 3.5876 4 1.3938 3.8092 4 108.32

6 a 1 IN I 2.3008 6.0448 4 2.3918 5.7574 4 103.96

6 a 2 IN 3 1.9839 4.6436 4 2.1271 4.7672 4 107.22

6 b 1 IN 3 1.9911 4.5241 4 2.1509 5.3843 4 108.03

6 b 2 IN I 2.1087 4.9442 4 2.1696 5.15 4 102.89

Subject 7 - Power-plate data

S.No.InsoleType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnkle p e a k ***

D.FAnkle

Trans INSOLEA nk*

1 a 1 IN 3 30.0657 5.0065 40 11.196 20.7362 40 37.2384478

1 a 2 IN I 29.6518 55.0784 40 14.0892 27.4066 40 47.51549653

l b l IN I 31.7473 51.6609 40 15.5626 26.9612 40 49.02023164

1 b 2 IN 3 10.0735 18.422 40 4.581 9.9345 40 45.47575321

2 a 1 IN 3 28.8407 52.8676 40 16.1295 29.3256 40 55.92617378

2 a 2 IN 2 28.6991 52.0684 40 11.9098 22.617 40 41.49886233

2 b 1 IN 2 12.5618 25.8566 40 9.5552 20.4083 40 76.06553201

2 b 2 IN 3 26.4536 48.4928 40 11.0144 26.7813 40 41.63667705

3 a 1 IN 3 18.3646 31.2255 40 11.5435 22.8568 40 62.85734511

3 a 2 NIN 11.8114 24.5282 40 12.06 26.8006 40 102.1047463

3 b 1 NIN 26.2065 51.1118 40 21.9216 40.023 40 83.64947627

3 b 2 IN 3 13.8654 27.2529 40 8.3549 16.0366 40 60.25718695

4 a 1 IN I 25.4384 47.6782 40 22.4582 46.2737 40 88.28464054

4 a 2 IN 2 27.0052 50.0468 40 12.9308 23.2395 40 47.88263001

4 b l IN 2 26.6282 48.7349 40 15.0016 29.0243 40 56.33726651

4 b 2 IN I 27.0911 48.9894 40 21.7863 44.8903 40 80.41866148

5 a 1 IN I 16.0855 30.7104 40 11.9178 23.6162 40 74.0903298

S a 2 NIN 24.7224 47.6475 40 22.9959 44.4556 40 93.01645471

S b l NIN 26.4034 47.5211 40 28.2375 54.8926 40 106.9464539

S b 2 IN I 11.3398 19.6459 40 7.9085 15.9009 40 69.74108891

6 a 1 IN 2 26.5966 48.9586 40 21.0005 40.9512 40 78.95934067

6 a 2 NIN 26.2017 52.9805 40 25.3762 50.2815 40 96.84944107

6 b l NIN 27.567 47.8905 40 24.2173 49.0915 40 87.84887728

6 b 2 IN 2 17.7084 38.5242 40 13.74 26.2864 40 77.59029613

187

Subject 7 - Vibration simulator data

S.NO.InsoleType

aR.M.SFloor peak floor

D.FB oor

aR.M.SAn id* PEAK Ankle D.F Ankle

Trans INSOLEAnkle

l a 1 IN I 1.4282 4.002 4 1.511 3.5163 4 105.7975074

l a 2 IN 2 1.4771 3.7107 4 1.5944 4.2397 4 107.9412362

l b l IN 2 1.498 4.0919 4 1.621 4.3075 4 108.2109479

1 b 2 IN I 1.5755 4.0465 4 1.6586 3.6883 4 105.274516

2 a 1 IN I 1.6428 4.3924 4 1.7764 4.5801 4 108.1324568

2 a 2 IN 3 1.7178 4.4116 4 1.9379 4.4637 4 112.8129002

2 b 1 IN 3 1.6991 4.1283 4 1.9158 4.8703 4 112.7538108

2 b 2 IN I 1.7309 5.3546 4 1.8991 4.9377 4 109.717488

3 a 1 IN I 1.7158 4.4562 4 1.8505 4.749 4 107.8505653

3 a 2 NIN 1.6606 4.3045 4 1.7774 4.6915 4 107.0336023

3 b 1 NIN 1.5929 3.9915 4 1.6921 4.4967 4 106.2276351

3 b 2 IN I 1.5775 3.5714 4 1.7228 4.4023 4 109.2107765

4 a 1 IN 2 1.4786 3.9711 4 1.5765 3.853 4 106.6211281

4 a 2 IN 3 1.6277 4.5134 4 1.8369 4.5871 4 112.8524912

4 b l IN 3 1.6844 4.9427 4 1.9193 5.1129 4 113.9456186

4 b 2 IN 2 1.6941 4.7 4 1.9413 4.3355 4 114.5918187

5 a 1 IN 2 1.6811 4.4016 4 1.9527 4.8742 4 116.1560883

S a 2 NIN 1.6515 4.0247 4 1.934 4.84 4 117.1056615

5 b 1 NIN 1.6569 4.9689 4 1.8772 4.4885 4 113.2959141

S b 2 IN 2 1.7412 4.7075 4 1.9595 4.3966 4 112.5373306

6 a 1 IN 3 1.5951 3.8249 4 1.7446 4.2381 4 109.3724531

6 a 2 NIN 1.5528 4.2687 4 1.7167 3.9459 4 110.5551262

6 b 1 NIN 1.5176 3.8346 4 1.6565 3.9553 4 109.1526094

6 b 2 IN 3 1.6411 3.9251 4 1.7708 4.105 4 107.9032356

Subject 8 - Power-plate data

S.No.InsoleType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnkle p e a k *,*.

D.FAnldo

Trans INSOLEAnkle

1 a 1 IN 2 29.5656 57.2508 40 7.6716 16.6943 40 25.94772303

1 a 2 IN I 28.2975 50.904 40 12.8736 23.3898 40 45.49377153

l b l IN I 13.3681 27.8889 40 6.7839 13.9933 40 50.74692739

1 b 2 IN 2 27.6916 51.4171 40 7.7555 14.7827 40 28.00668795

2 a 1 IN 2 20.036 38.9 40 8.2564 14.6244 40 41.20782591

2 a 2 IN 3 20.9855 40.1163 40 7.7718 14.831 40 37.03414262

2 b 1 IN 3 25.2037 45.5973 40 8.6932 15.1583 40 34.49176113

2 b 2 IN 2 10.9302 23.9748 40 4.759 10.1319 40 43.53991693

3 a 1 IN 2 22.1974 39.6292 40 9.9835 18.6415 40 44.97598818

3 a 2 NIN 23.7856 50.001 40 12.2038 25.1233 40 51.30751379

3 b 1 NIN 25.9054 46.1637 40 13.9152 24.661 40 53.71544157

3 b 2 IN 2 25.2987 43.2818 40 10.8451 19.7886 40 42.86821062

4 a 1 NIN 19.4273 40.7971 40 10.5638 20.9169 40 54.37605843

4 a 2 IN I 20.4295 40.229 40 11.4327 20.6719 40 55.96172202

4 b l IN I 16.1054 30.2323 40 7.6787 13.6485 40 47.67779751

4 b 2 NIN 20.1822 40.9147 40 11.1826 21.675 40 55.40823102

5 a 1 NIN 22.0948 43.4892 40 10.8556 19.5329 40 49.13192244

5 a 2 IN 3 27.4574 47.679 40 5.9725 12.4632 40 21.75187745

5 b 1 IN 3 23.2223 43.7396 40 4.9979 10.2717 40 21.52198533

5 b 2 NIN 25.7 52.2733 40 13.023 25.7099 40 50.67315175

6 a 1 IN I 27.1321 47.3773 40 12.2264 19.948 40 45.06249056

6 a 2 IN 3 27.8605 47.3785 40 7.0585 12.7837 40 25.33515192

6 b 1 IN 3 13.3477 28.3951 40 5.439 14.6572 40 40.74859339

6 b 2 IN I 28.2413 54.843 40 13.3529 24.221 40 47.28146367

Subject 8 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor P E A K n o o r

D.FFloor

aR.M.SAnkle PEAK / m u .

D.FAnkle

Trans INSOLEAnUe

l a 1 IN 3 1.23 2.6946 5 1.4104 3.4164 5 114.6666667

l a 2 IN I 1.3699 4.2382 5 1.5465 3.5411 5 112.8914519

l b l IN I 1.2959 3.4592 5 1.4857 3.3477 5 114.6461918

l b 2 IN 3 1.1932 3.0077 5 1.3289 2.9898 5 111.3727791

2 a 1 IN 3 1.2631 3.2138 5 1.476 3.2984 5 116.8553559

2 a 2 IN 2 1.3014 3.929 5 1.4965 3.6184 5 114.9915476

2 b 1 IN 2 1.2943 3.0632 5 1.4673 3.2889 5 113.3662984

2 b 2 IN 3 1.3514 3.189 5 1.5628 3.5478 5 115.6430369

3 a 1 IN 3 1.2836 3.2935 5 1.53 3.4019 5 119.1960112

3 a 2 NIN 1.3228 3.5704 5 1.4829 3.6148 5 112.1031146

3 b 1 NIN 1.3768 3.5794 5 1.5283 3.7831 5 111.0037769

3 b 2 IN 3 1.2776 3.2702 5 1.4986 3.5656 5 117.2980589

4 a 1 IN I 1.2466 4.0134 S 1.4074 3.2421 5 112.8990855

4 a 2 IN 2 1.2905 3.839 5 1.4465 3.3543 5 112.0883379

4 b l IN 2 1.2375 3.1144 5 1.4057 3.1821 5 113.5919192

4 b 2 IN I 1.349 3.5791 5 1.5614 3.4988 5 115.7449963

5 a 1 IN I 1.2567 3.0086 5 1.3807 3.4243 5 109.8671123

S a 2 NIN 1.3458 4.0298 5 1.4878 3.5833 5 110.5513449

5 b 1 NIN 1.1944 3.3314 5 1.279 3.0768 5 107.0830543

5 b 2 IN I 1.2667 3.4043 5 1.3941 3.7677 5 110.0576301

6 a 1 IN 2 1.2561 3.6244s;

6.3 1.3797 3.11685;

6.3 109.8399809

6 a 2 NIN 1.3162 3.4331 5 1.4655 3.409 5 111.3432609

6 b 1 NIN 1.3591 3.5051 5 1.489 3.5487 5 109.5577956

6 b 2 IN 2 1.2293 3.1972 5 1.3852 3.3529 5 112.6820142

Subject 9 - Power-plate data

S.No.InsoleType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAn Me p e a k ***

D.FAn Me

Trans INSOLEAnkle

1 a 1 IN 3 20.0975 40.9161 40 9.6435 20.011 40 47.98358005

1 a 2 NIN 17.8537 36.7771 40 15.9398 29.8631 40 89.2800932

l b l NIN 26.6432 44.3777 40 11.5688 34.2961 40 43.42121067

1 b 2 IN 3 14.6971 31.6528 40 13.5392 30.9155 40 92.121575

2 a 1 IN 3 27.8404 48.3112 40 18.0241 34.9371 40 64.74080832

2 a 2 IN 2 13.9385 28.5631 40 10.4732 22.7523 40 75.13864476

2 b 1 IN 2 28.3175 52.4601 40 20.8828 37.2212 40 73.74521056

2 b 2 IN 3 25.1682 44.4416 40 9.8229 30.1431 40 39.0290128

3 a 1 IN I 26.6547 50.5516 40 17.8168 30.4742 40 66.84299579

3 a 2 NIN 19.8225 36.2784 40 12.5018 25.8312 40 63.06873502

3 b 1 NIN 27.946 45.594 40 20.5354 38.6664 40 73.4824304

3 b 2 IN I 12.6906 23.212 40 9.2455 20.8756 40 72.85313539

4 a 1 IN 3 28.9587 46.5325 40 15.9479 31.9442 40 55.07118759

4 a 2 IN I 24.9153 41.1984 40 14.428 27.9283 40 57.90819296

4 b 1 IN I 14.649 31.1958 40 9.4525 21.777 40 64.52658885

4 b 2 IN 3 12.5504 24.2137 40 6.3172 13.97 40 50.33465069

S a l IN 2 22.848 43.537 40 11.0687 22.7919 40 48.44494048

5 a 2 NIN 31.9594 52.8869 40 16.977 33.8204 40 53.12052166

5 b l NIN 11.5749 20.593 40 7.5816 14.9184 40 65.5003499

5 b 2 IN 2 23.1793 42.0262 40 8.4885 19.2602 40 36.62103687

6 a 1 IN I 26.2172 52.1176 40 11.3394 21.5782 40 43.25175839

6 a 2 IN 2 28.1102 49.6755 40 14.1746 26.0148 40 50.42511259

6 b l IN 2 28.8689 48.2332 40 13.9258 25.3939 40 48.23806934

6 b 2 IN I 11.9103 21.8907 40 6.2577 12.8843 40 52.54023828

Subject 9 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle PEAK taa.

D.FAnkle

Trans INSOLEAnkle

1 a 1 NIN 1.0365 3.1037 5 1.2431 4.1117 5 119.932465

1 a 2 IN I 1.0389 2.682 5 1.2197 2.8903 5 117.4030224

l b l IN I 1.0258 2.8514 5 1.1859 3.219 5 115.6073309

l b 2 NIN 1.0694 2.8181 5 1.1832 2.6916 5 110.6414812

2 a 1 NIN 1.0454 3.3488 5 1.2449 4.3912 5 119.0836044

2 a 2 IN 2 1.134 3.2555 5 1.2919 3.8245 5 113.9241623

2 b 1 IN 2 1.6909 3.3422 5 1.2711 3.7288 5 75.1729848

2 b 2 NIN 1.1871 2.7502 5 1.2634 4.3744 5 106.4274282

3 a 1 NIN 1.1972 3.4949 5 1.2586 3.7998 5 105.1286335

3 a 2 IN 3 1.1044 2.9249 5 1.1978 3.1117 5 108.4570808

3 b 1 IN 3 1.1216 3.420S 5 1.207 3.2957 5 107.6141227

3 b 2 NIN 1.2136 3.2505 5 1.243 3.4203 5 102.4225445

4 a 1 IN 2 1.1105 4.2554 5 1.2807 4.5276 5 115.3264295

4 a 2 IN I 1.1619 2.8278 5 1.2647 3.9367 5 108.8475772

4 b 1 IN I 1.159 2.8399 5 1.2314 3.6679 5 106.2467645

4 b 2 IN 2 1.1036 3.3139 5 1.1754 3.5073 5 106.5059804

5 a 1 IN 2 1.1191 3.1027 5 1.2405 3.6066 5 110.8480029

5 a 2 IN 3 1.1759 3.2594 5 1.1897 3.2134 5 101.1735692

S b l IN 3 1.1788 3.1241 5 1.2342 3.2961 5 104.6996946

5 b 2 IN 2 1.777 3.3943 5 1.2576 4.0423 5 70.7709623

6 a 1 IN I 1.204 3.1826 5 1.2541 3.4776 5 104.1611296

6 a 2 IN 3 1.1313 3.0109 5 1.1629 3.423 5 102.7932467

6 b 1 IN 3 1.1587 2.8816 5 1.2181 3.823 5 105.1264348

6 b 2 IN I 1.175 3.2769 5 1.2679 3.8542 5 107.906383

Subject 10- Power-plate data

S.No.InsoleType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnkle PEAK ^

D.FAn Me

Trans INSOLEAnUe

l a l IN 3 15.0158 39.121 40 23.6346 51.1462 40 157.3982072

1 a 2 IN I 11.9022 22.1756 40 19.5195 40.9729 40 163.9990926

l b l IN I 32.971 54.5372 40 20.5087 37.4887 40 62.20223833

l b 2 IN 3 28.6332 49.685 40 21.9239 38.8558 40 76.S681097S

2 a 1 IN 3 15.6683 44.9632 40 9.7819 23.5817 40 62.43115079

2 a 2 IN 2 29.3392 49.766 40 25.5245 48.2772 40 86.99794132

2 b 1 IN 2 24.3193 45.0339 40 26.0583 45.3059 40 107.1506992

2 b 2 IN 3 27.5531 48.7153 40 29.6609 53.2531 40 107.6499559

3 a 1 IN 3 21.9769 47.6323 40 31.9945 60.7716 40 145.582407

3 a 2 NIN 31.6928 50.7586 40 24.2764 44.4206 40 76.59910137

3 b 1 NIN 24.2608 50.9643 40 27.4234 52.0812 40 113.0358438

3 b 2 IN 3 11.1657 26.9133 40 18.8047 36.5062 40 168.4148777

4 a 1 IN I 21.4267 34.796 40 25.039 44.296 40 116.8588723

4 a 2 IN 2 27.9241 43.706 40 23.6942 41.8394 40 84.8521528

4 b 1 IN 2 16.0826 48.0885 40 20.6702 51.2074 40 128.5252385

4 b 2 IN I 28.4228 56.5775 40 55.842 103.4228 40 196.4690319

5 a 1 IN I 12.906 28.5061 40 20.3761 47.6408 40 157.8808306

5 a 2 NIN 29.9384 50.3144 40 26.9438 50.8241 40 89.99746145

S b l NIN 31.5274 47.7445 40 30.0563 50.693 40 95.33390004

5 b 2 IN I 32.099 47.8983 40 28.6969 47.223 40 89.40122745

6 a 1 IN 2 24.3891 54.5508 40 33.088 58.8135 40 135.6671628

6 a 2 NIN 12.9186 27.2626 40 26.4598 47.2503 40 204.8194077

6 b l NIN 23.172 44.4616 40 20.5448 36.5551 40 88.66217849

6 b 2 IN 2 23.7721 44.4398 40 49.757 86.3453 40 209.3083909

Subject 10 - Vibration simulator data

S.No.InsoleType

aR.M.SH oof PEAK Ftoo,

D.FFloor

aR.M.SH M t PEAK Aoklo

D.FAnkle

Trans INSOLE•o ld e

l a 1 IN I 1.31S8 3.8654 4 1.5414 4.5579 4 117.1454628

l a 2 IN 2 1.2856 4.0042 4 1.5536 4.1437 4 120.8462974

l b l IN 2 1.3627 4.1003 4 1.6677 4.523 4 122.3820357

l b 2 IN I 1.309 3.5344 4 1.5262 3.8621 5 116.5928189

2 a l IN I 1.34S3 3.7558 4 1.528 4.0443 4 113.580614

2 a 2 IN 3 1.3022 3.8839 4 1.5017 4.1129 4 115.3202273

2 b 1 IN 3 1.2846 3.8239 4 1.4968 3.7759 4 116.5187607

2 b 2 IN I 1.3475 3.6687 4 1.4914 3.7234 4 110.6790353

3 a 1 IN I 1.3543 3.7005 4 1.5817 3.9218 4 116.7909621

3 a 2 NIN 1.3295 3.5347 4 1.4364 3.5835 4 108.0406168

3 b 1 NIN 1.3224 3.6092 4 1.4787 3.8887 4 111.8194192

3 b 2 IN I 1.3258 3.9684 4 1.4821 3.8277 4 111.7891085

4 a 1 IN 2 1.8951 4.8741 4 2.0768 4.392 4 109.5878845

4 a 2 IN 3 2.0176 5.3677 4 2.2717 5.6592 4 112.5941713

4 b 1 IN 3 1.9532 4.7843 4 2.1729 4.5411 4 111.2482081

4 b 2 IN 2 1.7794 5.3292 4 1.9828 4.6114 4 111.4308194

5 a 1 IN 2 2.1327 5.4455 4 2.3142 5.1971 4 108.510339

5 a 2 NIN 2.004 5.1246 4 2.1988 5.4579 4 109.7205589

5 b 1 NIN 1.9856 5.122 4 2.0433 4.7859 4 102.9059226

5 b 2 IN 2 2.0322 5.9384 4 2.2621 5.4076 4 111.3128629

6 a 1 IN 3 1.9863 5.3079 4 2.214 5.1631 4 111.4635251

6 a 2 NIN 2.0171 4.7281 4 2.1449 5.0216 4 106.3358287

6 b 1 NIN 1.9314 4.7088 4 2.1277 5.0449 4 110.1636119

6 b 2 IN 3 2.0604 4.7293 4 2.3926 5.4387 4 116.1230829

Subject 11- Power-plate data

S.No.InsoleType

aR.M.SFleer

PEAKFloor

D.FFloor

aR.M.SAnUe PEAK

D.FAnUc

Trans INSOLEAitUe

l a 1 IN 3 8.9627 19.0473 40 4.7684 10.554 40 53.20271793

1 a 2 IN I 17.396S 39.2235 40 16.9878 36.1298 40 97.65067686

l b l IN I 9.9654 24.5378 40 22.4774 42.8709 40 225.5544183

1 b 2 IN 3 23.5061 42.9145 40 15.6263 27.278 40 66.47763772

2 a 1 IN 3 15.0723 28.9078 40 16.5596 28.7695 40 109.8677707

2 a 2 IN 2 22.8 44.17 40 17.9286 32.7522 40 78.63421053

2 b 1 IN 2 12.0741 26.796 40 7.0157 13.8966 40 58.10536603

2 b 2 IN 3 22.5677 42.1013 40 14.445 26.6108 40 64.00740882

3 a 1 IN 3 24.2987 44.1417 40 15.0228 26.7196 40 61.82552976

3 a 2 NIN 9.3867 20.4176 40 9.5739 20.8865 40 101.9943111

3 b 1 NIN 9.6392 20.9987 40 9.4723 21.4747 40 98.26852851

3 b 2 IN 3 12.0033 22.244 40 6.2376 11.8062 40 51.96570943

4 a 1 IN I 16.4217 29.1033 40 16.0643 26.5238 40 97.82361144

4 a 2 IN 2 28.1618 47.4275 40 12.8458 22.0742 40 45.61427182

4 b 1 IN 2 25.1133 44.9347 40 17.3497 28.3657 40 69.08570359

4 b 2 IN I 27.2881 47.0413 40 16.0412 29.6476 40 58.78459841

5 a 1 IN I 19.5779 37.1322 40 16.4038 31.6218 40 83.78733163

5 a 2 NIN 18.731 40.3841 40 13.1169 28.3138 40 70.02776146

5 b 1 NIN 19.8705 42.4593 40 19.0063 33.4505 40 95.65083918

5 b 2 IN I 20.594 39.9058 40 13.4837 24.8264 40 65.47392444

6 a 1 IN 2 21.3015 44.8306 40 7.6395 15.1678 40 35.86367157

6 a 2 NIN 21.8611 48.1782 40 17.3346 39.9276 40 79.29427156

6 b l NIN 19.7744 44.5864 40 16.2714 33.9535 40 82.28517679

6 b 2 IN 2 27.3258 53.0009 40 11.1469 21.1136 40 40.7925843

Subject 11 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnUc PEAK Ankle

D.FAnUc

Trans INSOLEAnlde

l a 1 IN 2 1.466 4.7597 4 1.7342 4.3253 4 118.2946794

l a 2 IN I 1.5247 4.1324 4 1.8939 5.0285 4 124.2145996

l b l IN I 1.5078 3.7428 4 1.7759 4.3321 4; 5 117.7808728

1 b 2 IN 2 1.474 3.9718 4 1.9129 4.8162 4 129.7761194

2 a 1 IN 2 1.5032 4.474 4 1.9243 5.0745 4 128.013571

2 a 2 IN 3 1.4815 4.528 4 1.9594 5.2984 4 132.2578468

2 b l IN 3 1.486 4.3143 4 1.9096 5.0379 4 128.5060565

2 b 2 IN 2 1.5107 4.3683 4 1.8552 4.8979 4 122.8039981

3 a 1 IN 2 1.5081 4.0993 4 1.8393 4.8391 4 121.9614084

3 a 2 NIN 1.49 5.0872 4 1.8743 5.6314 4 125.7919463

3 b l NIN 1.5377 4.3938 4 1.8981 5.7045 4 123.4376016

3 b 2 IN 2 1.5474 4.536 4 1.8356 5.2975 4 118.62479

4 a l NIN 1.578 4.1634 4 1.8495 5.446 4 117.2053232

4 a 2 IN I 1.5665 5.5412 4 1.9564 5.5156 4 124.8898819

4 b 1 IN I 1.5266 4.5365 4 1.958 5.5641 4 128.2588759

4 b 2 NIN 1.5214 5.1032 4 1.9274 5.3906 4 126.6859472

S a l NIN 1.5262 4.1892 4 1.9199 5.3569 4 125.7960949

S a 2 IN 3 1.5391 5.0244 4 1.8692 5.133 4 121.4475992

5 b 1 IN 3 1.5616 4.8779 4 1.9117 5.1132 4 122.4193135

5 b 2 NIN 1.6119 4.9518 4 1.9766 5.8641 4 122.625473

6 a 1 IN I 1.558 1.7557 4 1.8949 5.2131 4 121.6238768

6 a 2 IN 3 1.5328 4.0982 4 1.9644 5.2949 4 128.15762

6 b l IN 3 1.4995 4.3633 4 1.9239 5.0657 4 128.3027676

6 b 2 IN I 1.5187 4.5737 4 1.9416 5.4464 4 127.8461842

Subject 12- Power-plate data

S.No.InsoleType

aR.M.SFloor PEAK f,o„.

D.FFlow

aR.M.SAnkle PEAK Ankle

D.FAnkle

Trans INSOLEAnlde

l a 1 IN 3 11.4905 21.1947 40 2.1556 5.6726 40 18.75984509

l a 2 NIN . 23.1972 43.5761 40 5.5162 14.4936 40 23.77959409

l b l NIN 13.005 28.6715 40 3.8684 9.1903 40 29.74548251

1 b 2 IN 3 25.2466 41.8188 40 5.5358 10.499S 40 21.92691293

2 a 1 IN 3 20.5086 39.2594 40 3.363 7.8688 40 16.39799889

2 a 2 IN 2 26.8453 44.4719 40 6.5582 12.8938 40 24.4296022

2 b 1 IN 2 25.5959 49.7972 40 6.9318 14.3615 40 27.08168105

2 b 2 IN 3 28.4209 46.5104 40 6.1953 13.0025 40 21.79839484

3 a 1 IN I 27.5606 52.3153 40 4.8273 10.8012 40 17.515221

3 a 2 NIN 14.8873 30.4311 40 5.8372 12.397 40 39.2092589

3 b 1 NIN 18.1324 35.6934 40 4.5619 12.2795 40 25.1588317

3 b 2 IN I 21.8896 38.3283 40 4.2416 10.2446 40 19.37723851

4 a 1 IN 3 10.0004 22.3776 40 1.5981 6.5176 40 15.98036079

4 a 2 IN I 27.8434 47.9673 40 3.5211 7.7545 40 12.64608489

4 b 1 IN I 26.9984 51.1535 40 4.5035 10.6009 40 16.68061811

4 b 2 IN 3 28.7975 50.6279 40 5.3957 13.7301 40 18.73669589

S a l IN 2 17.2104 36.2066 40 4.6731 11.3273 40 27.15276809

S a 2 NIN 28.2189 46.7444 40 5.3941 12.4439 40 19.11520293

S b l NIN 26.3466 51.8156 40 6.134 12.6378 40 23.2819415

5 b 2 IN 2 22.3322 52.1544 40 2.5359 7.2199 40 11.35535236

6 a 1 IN I 29.8111 52.3489 40 3.1727 7.6072 40 10.64268008

6 a 2 IN 2 28.5798 48.9551 40 5.9095 13.1767 40 20.67719158

6 b 1 IN 2 25.2078 42.5339 40 6.3898 15.5988 40 25.34850324

6 b 2 IN I 26.067 44.6794 40 3.6164 8.1931 40 13.87347988

Subject 12 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnld* PEAK jbiu.

D.FAnld*

Trans INSOLEAnld*

l a 1 NIN 1.3572 3.1675 6.3 1.4005 3.2677 6.3 103.190392

1 a 2 IN I 1.3448 3.0418 5 1.4088 3.2304 5 104.759072

l b l IN I 1.4871 3.1335 5 1.594 3.76 5 107.1884877

1 b 2 NIN 1.5462 3.4555 5 1.6682 3.9585 5 107.8903117

2 a 1 NIN 1.5095 3.8365 5 1.6077 3.8904 5 106.5054654

2 a 2 IN 2 1.4669 3.9614 5 1.6123 3.6581 5 109.9120594

2 b 1 IN 2 1.4677 4.2063 5 1.6081 4.4725 5 109.5659876

2 b 2 NIN 1.5033 3.2067 5 1.5631 3.73 5 103.9779153

3 a 1 NIN 1.5465 3.8093 5 1.6188 3.9159 5 104.6750727

3 a 2 IN 3 1.4436 3.6641 5 1.5449 3.6032 5 107.0171793

3 b 1 IN 3 1.4092 3.316 5 1.4988 3.5922 5 106.3582174

3 b 2 NIN 1.5559 4.0787 5 1.6854 3.8872 5 108.323157

4 a 1 IN 2 1.3924 2.9243 5 1.5511 3.5549 5 111.3975869

4 a 2 IN I 1.5091 3.2218 5 1.62 3.6813 5 107.3487509

4 b 1 IN I 1.4491 3.2037 5 1.5341 3.8858 5 105.8657098

4 b 2 IN 2 1.3733 3.2782 5 1.5422 3.692 5 112.2988422

5 a l IN 2 1.3685 3.373 5 1.5098 3.7102 5 110.3251735

5 a 2 IN 3 1.381 3.6627 5 1.5207 3.6395 5 110.1158581

S b l IN 3 1.3599 3.0196 5 1.47 3.388 5 108.0961835

5 b 2 IN 2 1.372 3.2458 4 1.4765 3.6297 5 107.6166181

6 a 1 IN I 1.4836 3.4461 5 1.5291 3.7294 5 103.0668644

6 a 2 IN 3 1.3358 3.8634 5 1.4753 3.2988 5 110.4431801

6 b 1 IN 3 1.3486 3.0135 5 1.449 3.3127 5 107.4447575

6 b 2 IN I 1.4195 3.0775 5 1.5312 3.8841 5 107.8689679

198

Subject 13- Power-plate data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKA/i Me

D.FAnkle Trans INSOLE Ankie

l a 1 IN 3 29.6018 48.0235 40 18.8501 38.3201 40 63.6788979

l a 2 IN I 28.9235 49.4683 40 17.5413 32.5661 40 60.64722458

l b l IN I 29.1082 51.88 40 22.796 40.8938 40 78.3147017

l b 2 IN 3 27.2747 47.7017 40 18.4983 40.1629 40 67.82219419

2 a 1 IN 3 11.913 21.4938 40 8.0351 16.6484 40 67.44816587

2 a 2 IN 2 27.5701 45.2733 40 20.137 38.2035 40 73.0392708

2 b 1 IN 2 16.8922 37.2493 40 13.2519 26.519 40 78.44981708

2 b 2 IN 3 27.9885 48.8738 40 25.6777 58.0607 40 91.7437519

3 a 1 IN 3 29.3706 49.5811 40 16.2328 28.345 40 55.26887432

3 a 2 NIN 26.9432 47.486 40 19.9074 45.9398 40 73.88654651

3 b 1 NIN 16.1394 35.767 40 17.21 35.0297 40 106.633456

3 b 2 IN 3 29.1186 53.1455 40 18.9958 40.1909 40 65.23596601

4 a 1 IN I 28.8557 48.776 40 24.8619 39.055 40 86.15940698

4 a 2 IN 2 28.3544 47.0364 40 21.1644 35.9703 40 74.64238355

4 b 1 IN 2 26.7923 47.2967 40 19.4153 37.5328 40 72.4659697

4 b 2 IN I 9.6978 21.6871 40 8.1772 18.8886 40 84.32015509

5 a 1 IN I 26.2206 42.4125 40 17.8453 37.5247 40 68.05832056

5 a 2 NIN 28.6688 47.4834 40 26.2152 46.1412 40 91.44156714

5 b 1 NIN 27.085 42.6 40 26.8302 48.3336 40 99.05925789

5 b 2 IN I 25.5135 42.2958 40 21.7651 35.8286 40 85.30817018

6 a 1 IN 2 25.2968 44.9782 40 19.21 35.9261 40 75.93845862

6 a 2 NIN 27.7465 49.7971 40 22.2276 48.9149 40 80.10956337

6 b 1 NIN 28.8793 50.9703 40 21.8228 47.4474 40 75.56554349

6 b 2 IN 2 27.6223 52.5206 40 19.5622 45.0124 40 70.82031547

Subject 13 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnld*

PEAKAnUc

D.FAnkle

Trans INSOLEAnld*

l a l IN I 1.3881 3.4533 4 1.5866 4.2444 4 114.3001225

1 a 2 IN 2 1.3512 3.7161 4 1.4926 4.2216 4 110.4647721

l b l IN 2 1.302 3.8092 4 1.3927 3.6534 4 106.9662058

1 b 2 IN I 1.2795 3.3401 4 1.3642 3.547 4 106.6197733

2 a 1 IN I 1.319 4.0458 4 1.4255 3.7829 4 108.0742987

2 a 2 IN 3 1.3714 3.699 4 1.3854 3.7357 4 101.0208546

2 b 1 IN 3 1.3282 3.6432 4 1.4011 3.9294 4 105.4886312

2 b 2 IN I 1.5858 4.0006 4 1.5417 3.7446 4 97.21906924

3 a 1 IN I 1.4582 3.6035 4 1.5202 3.7976 4 104.2518173

3 a 2 NIN 1.5535 3.9089 4 1.5902 3.6204 4 102.3624075

3 b 1 NIN 1.6349 3.8023 4 1.6076 3.3743 4 98.3301731

3 b 2 IN I 1.5106 3.7729 4 1.5671 3.7029 4 103.7402357

4 a 1 IN 2 1.5866 3.5383 4 1.6543 3.5519 4 104.266986

4 a 2 IN 3 1.7587 4.2053 4 1.586 3.3584 4 90.18024677

4 b 1 IN 3 1.5527 4.0425 4 1.508 4.1005 4 97.12114381

4 b 2 IN 2 1.6067 4.1005 4 1.529 3.3482 4 95.16400075

5 a 1 IN 2 1.5931 3.7646 4 1.62 3.449 4 101.6885318

5 a 2 NIN 1.6227 4.468 4 1.5926 3.8162 4 98.14506686

5 b 1 NIN 1.617 3.8536 4 1.6038 3.4988 4 99.18367347

5 b 2 IN 2 1.6552 4.5852 4 1.642 3.5493 4 99.20251329

6 a 1 IN 3 1.5213 3.0528 4 1.6033 3.3466 4 105.3901269

6 a 2 NIN 1.643 3.8066 4 1.6055 3.4295 4 97.71758977

6 b 1 NIN 1.6387 4.1414 4 1.5746 3.5905 4 96.08836273

6 b 2 IN 3 1.5024 3.4699 4 1.6052 3.8405 4 106.8423855

Subject 14- Power-plate data

S.No.InsoleType

aR.M.Sflo o r

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnUc

Trans INSOLEAnUc

1 a 1 IN 3 16.0948 30.6617 40 3.3356 7.7708 40 20.72470612

1 a 2 IN I 30.093 49.705 40 9.0184 17.4165 40 29.9684312

l b l IN I 21.2694 38.6772 40 6.9144 13.8161 40 32.50867443

l b 2 IN 3 11.7996 24.3506 40 1.7236 3.984 40 14.60727482

2 a 1 IN 3 29.6562 52.1748 40 6.0432 13.6802 40 20.37752645

2 a 2 IN 2 27.8405 45.7101 40 3.7497 6.7293 40 13.46850811

2 b 1 IN 2 15.9027 35.724 40 1.3796 3.9812 40 8.675256403

2 b 2 IN 3 25.4944 44.2057 40 4.87 9.2685 40 19.10223422

3 a l IN 3 25.9318 46.1632 40 3.6236 7.6224 40 13.97357684

3 a 2 NIN 24.7019 46.853 40 6.5834 15.0676 40 26.65139119

3 b 1 NIN 26.136 47.6069 40 8.1132 17.3963 40 31.04224059

3 b 2 IN 3 10.2594 18.7597 40 1.7638 4.0544 40 17.19203852

4 a 1 IN I 20.7692 44.4332 40 8.2447 17.1612 40 39.69676251

4 a 2 IN 2 28.8686 47.1456 40 4.1078 9.0942 40 14.22930104

4 b 1 IN 2 25.5201 42.46 40 1.9518 4.1981 40 7.648089153

4 b 2 IN I 26.6322 45.5856 40 26.6322 45.5856 40 100

S a l IN I 26.0353 46.1152 40 6.5848 15.1474 40 25.29181534

5 a 2 NIN 24.1327 44.3736 40 7.3965 17.1425 40 30.649285

5 b 1 NIN 23.3109 42.3496 40 8.1073 18.4481 40 34.77900896

5 b 2 IN I 25.547 48.5748 40 5.453 12.4067 40 21.34497201

S a l IN 2 10.574 29.8956 40 1.3622 5.4048 40 12.88254208

6 a 2 NIN 20.0498 36.654 40 7.0406 16.3272 40 35.11556225

6 b 1 NIN 24.4876 44.9602 40 7.4938 16.2194 40 30.60242735

6 b 2 IN 2 21.0771 40.7009 40 2.4914 5.5874 40 11.82041173

201

Subject 14 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAn kit

PEAKAnkle

D.FAnld*

Trans INSOLEAnkle

1 a 1 IN 2 1.6541 4.1668 4 1.9341 4.6905 4 116.9276344

l a 2 IN I 1.6831 4.3284 4 1.9363 5.1908 4 115.0436694

l b l IN I 1.6666 4.2013 4 1.9209 4.9031 4 115.2586103

1 b 2 IN 2 1.6692 4.0952 4 1.9195 5.453 4 114.9952073

2 a 1 IN 2 1.6472 4.2914 4 1.9099 5.7192 4 115.9482759

2 a 2 IN 3 1.6431 4.4884 4 1.9787 5.2333 4 120.4248068

2 b 1 IN 3 1.6466 3.9799 4 1.8795 4.8691 4 114.1442973

2 b 2 IN 2 1.6922 4.2103 4 1.9737 4.8577 4 116.6351495

3 a 1 IN 2 1.6527 4.6564 4 1.8959 5.2518 4 114.7153143

3 a 2 NIN 1.7245 4.1824 4 1.9449 5.4967 4 112.7805161

3 b 1 NIN 1.7699 4.353 4 1.9546 4.709 4 110.4356178

3 b 2 IN 2 1.6789 4.214 4 1.875 4.8176 4 111.6802668

4 a 1 NIN 1.6596 4.1881 4 1.8351 5.0891 4 110.5748373

4 a 2 IN I 1.7525 4.6557 4 1.8488 4.3076 4 105.4950071

4 b 1 IN I 1.6956 4.5059 4 1.8626 4.5107 4 109.849021

4 b 2 NIN 1.7846 5.0404 4 1.956 5.6107 4 109.6043931

5 a 1 NIN 1.6923 4.5035 4 1.9759 4.8467 4 116.7582S8

5 a 2 IN 3 1.6834 4.8055 4 1.8623 4.6026 4 110.6273019

5 b 1 IN 3 1.6212 4.4324 4 1.9049 5.3102 4 117.4993832

5 b 2 NIN 1.7972 4.7858 4 1.9773 6.0144 4 110.021144

6 a 1 IN I 1.853 4.6415 4 2.1353 5.9482 4 115.2347545

6 a 2 IN 3 1.705 4.2191 4 2.091 5.2747 4 122.6392962

6 b 1 IN 3 1.5869 4.1735 4 1.9645 4.6641 4 123.7948201

6 b 2 IN I 1.5188 3.6854 4 1.7554 4.0504 4 115.578088

202

Subject 15- Power-plate data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAn Me

D.FAnkle

Trans INSOLEAnlde

l a l IN 3 12.3977 27.075 40 12.2091 23.9167 40 98.47875009

1 a 2 NIN 11.S675 30.7855 40 11.0824 31.166 40 95.80635401

l b l NIN 17.5659 35.7117 40 6.5903 19.323 40 37.51757667

l b 2 IN 3 24.2848 53.7577 40 7.6895 20.0932 40 31.66383911

2 a 1 IN 3 11.1967 30.5063 40 2.7227 7.2688 40 24.31698625

2 a 2 IN 2 18.7155 41.3875 40 4.5654 15.4315 40 24.39368438

2 b 1 IN 2 17.7146 36.6142 40 11.5456 26.9178 40 65.17561785

2 b 2 IN 3 10.8827 30.4069 40 5.4 14.0904 40 49.62003914

3 a 1 IN I 10.9068 26.5393 40 11.049 24.077 40 101.3037738

3 a 2 NIN 11.78 32.3709 40 11.0617 27.4966 40 93.90237691

3 b 1 NIN 14.7044 34.9725 40 11.0196 20.9867 40 74.94083404

3 b 2 IN I 25.1256 50.9611 40 37.1564 72.4097 40 147.8826376

4 a 1 IN 3 14.0892 34.2967 40 2.001 5.0888 40 14.20236777

4 a 2 IN I 14.0246 29.4882 40 17.492 31.8319 40 124.7236998

4 b 1 IN I 11.7017 35.3873 40 8.2208 25.0843 40 70.25304016

4 b 2 IN 3 24.9129 47.7912 40 23.2477 45.5637 40 93.31591264

5 a 1 IN 2 21.6886 42.152 40 24.0643 54.4492 40 110.9536807

5 a 2 NIN 20.9087 45.8432 40 36.3757 69.8039 40 173.9739917

5 b 1 NIN 23.7143 46.4668 40 24.1254 42.4085 40 101.7335532

S b 2 IN 2 24.952 42.354 40 14.2431 23.7668 40 57.08199744

6 a 1 IN I 30.3412 53.9761 40 37.6272 68.9059 40 124.0135525

6 a 2 IN 2 27.6688 51.9772 40 31.1419 50.3553 40 112.5524056

6 b 1 IN 2 22.4296 42.5438 40 28.415 53.9291 40 126.685273

6 b 2 IN I 12.4053 19.6728 40 16.955 35.431 40 136.6754532

2 03

Subject 15 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.Ffloo r

aR.M.SAnkle

PEAKAn Me

D.FAn Me

Trans INSOLEAnkle

l a l NIN 1.4203 4.1841 4 1.5854 4.0862 4 111.6243047

1 a 2 IN I 1.3745 3.8993 4 1.5298 4.1692 4 111.2986541

l b l IN I 1.4095 3.9216 4 1.5278 3.826 4 108.3930472

1 b 2 NIN 1.4049 4.2355 4 1.496 4.1233 4 106.4844473

2 a 1 NIN 1.3932 4.0412 4 1.5419 4.0872 4 110.6732702

2 a 2 IN 2 1.4113 3.8684 4 1.5598 4.0189 4 110.5222136

2 b 1 IN 2 1.3571 3.7665 4 1.5325 3.9876 4 112.9246187

2 b 2 NIN 1.397 3.7699 4 1.4697 3.7349 4 105.2040086

3 a 1 NIN 1.4261 4.4826 4 1.5444 4.1362 4 108.295351

3 a 2 IN 3 1.3908 4.3318 4 1.5956 4.1796 4 114.7253379

3 b 1 IN 3 1.4006 4.3694 4 1.6295 4.2714 4 116.3429959

3 b 2 NIN 1.4732 4.0615 4 1.5536 3.9121 4 105.4575075

4 a 1 IN 2 1.4372 4.4904 4 1.6788 4.7416 4 116.8104648

4 a 2 IN I 1.4247 4.0094 4 1.6413 4.4411 4 115.2032007

4 b 1 IN I 1.4354 4.2093 4 1.6325 4.2653 4 113.7313641

4 b 2 IN 2 1.4163 4.0358 4 1.6878 4.4275 4 119.1696674

S a l IN 2 1.4305 3.7379 4 1.6812 4.3351 4 117.5253408

5 a 2 IN 3 1.3998 3.9923 4 1.6238 4.4192 4 116.002286

S b l IN 3 1.4616 3.8631 4 1.6294 3.8666 4 111.4805692

5 b 2 IN 2 1.395 3.6956 4 1.6643 4.3949 4 119.3046595

6 a 1 IN I 1.3939 3.7381 4 1.6211 4.3566 4 116.2995911

6 a 2 IN 3 1.4455 3.7954 4 1.6734 4.1622 4 115.7661709

6 b 1 IN 3 1.4369 3.9607 4 1.6607 4.2004 4 115.5751966

6 b 2 IN I 1.4366 3.9175 4 1.6337 4.4487 4 113.7198942

Subject 16- Power-plate data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.Ffloo r

aR.M.SAnkle

PEAKAnkle

D.FAnkle

Trans INSOLEAnkla

l a l IN I 30.5314 52.5921 40 16.1461 31.8791 40 52.8835887

1 a 2 IN 2 12.6141 33.4279 40 5.3604 14.0921 40 42.49530288

l b l IN 2 24.437 50.7022 40 9.5997 20.5853 40 39.2834636

1 b 2 IN I 27.2156 47.7369 40 11.2644 23.9735 40 41.3894972

2 a 1 IN I 32.8846 56.9799 40 14.871 29.4663 40 45.22177554

2 a 2 IN 3 24.898 55.5456 40 9.1216 19.1944 40 36.63587437

2 b l IN 3 28.5525 53.4165 40 5.8953 14.6082 40 20.64722879

2 b 2 IN I 33.4556 52.2755 40 15.9475 28.9506 40 47.66765504

3 a 1 IN I 26.6776 45.9124 40 11.3072 22.5326 40 42.3846223

3 a 2 NIN 31.1507 53.3048 40 14.9468 29.031 40 47.98222833

3 b 1 NIN 28.3943 48.7605 40 14.5756 27.416 40 51.33283793

3 b 2 IN I 29.114 60.5467 40 12.283 22.4263 40 42.18932472

4 a 1 IN 2 31.464 51.8388 40 5.3975 13.0812 40 17.15452581

4 a 2 IN 3 20.306 37.2337 40 6.2768 15.824 40 30.91106077

4 b 1 IN 3 25.5086 52.5449 40 9.1909 19.6097 40 36.0305936

4 b 2 IN 2 30.2946 48.0794 40 10.9075 22.9969 40 36.00476653

S a l IN 2 32.31 52.1096 40 8.5713 15.0676 40 26.52831941

5 a 2 NIN 26.4256 61.6314 40 8.9858 22.0541 40 34.00414749

5 b 1 NIN 24.8395 47.5475 40 13.4546 26.5252 40 54.16614666

5 b 2 IN 2 28.6826 52.5344 40 6.7679 15.1906 40 23.59583859

6 a 1 IN 3 30.4603 47.3239 40 3.4553 9.2168 40 11.34361776

6 a 2 NIN 29.2931 51.0056 40 13.3866 26.0648 40 45.69881644

6 b 1 NIN 10.8466 19.7741 40 5.2117 11.5119 40 48.04915826

6 b 2 IN 3 10.3737 23.8746 40 2.7033 6.8086 40 26.05916886

205

Subject 16 - Vibration simulator data

S.No.InsoleType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

Trans INSOLEAnkle

l a 1 IN 3 1.5027 3.9818 4 1.8375 4.5143 4 122.2798962

l a 2 IN I 1.4685 4.0182 4 1.8857 4.8981 4 128.4099421

1 b 1 IN I 1.4689 3.9413 4 1.8159 4.4966 4 123.6231193

l b 2 IN 3 1.4473 4.3839 4 1.7898 3.9912 4 123.6647551

2 a 1 IN 3 1.4533 3.9897 4 1.8523 6.8428 4 127.4547581

2 a 2 IN 2 1.5313 4.2651 4 1.9389 6.5795 4 126.6179064

2 b 1 IN 2 1.5266 5.2495 4 1.9103 6.4482 4 125.1342853

2 b 2 IN 3 1.5573 4.0501 4 1.9094 4.6104 4 122.6096449

3 a 1 IN 3 1.4982 4.1202 4 1.8791 5.27 4 125.4238419

3 a 2 NIN 1.6196 4.4086 4 1.9596 6.1467 4 120.9928377

3 b 1 NIN 1.4927 3.7862 4 1.8028 4.3379 4 120.7744356

3 b 2 IN 3 1.5503 4.0305 4 1.9897 7.0783 4 128.3429014

4 a 1 IN I 1.5521 4.194 4 1.9104 4.5689 4 123.0848528

4 a 2 IN 2 1.6283 4.1526 4 1.9934 5.9473 4 122.4221581

4 b 1 IN 2 1.5733 4.7735 4 1.9243 5.9559 4 122.3097947

4 b 2 IN I 1.6458 4.1757 4 2.0538 6.0243 4 124.7903755

5 a 1 IN I 1.5666 3.9838 4 1.9969 5.2175 4 127.4671263

5 a 2 NIN 1.7244 5.0565 4 1.9657 6.24 4 113.993273

5 b 1 NIN 1.5598 4.4939 4 1.9534 6.0653 4 125.2340044

5 b 2 IN I 1.5462 5.061 4 1.9104 4.8151 4 123.5545208

6 a 1 IN 2 1.5439 3.9767 4 1.9662 4.6369 4 127.3528078

6 a 2 NIN 1.4987 4.0093 4 1.8691 4.5885 4 124.7147528

6 b 1 NIN 1.5216 4.2033 4 1.8074 4.3138 4 118.7828601

6 b 2 IN 2 1.4903 4.1188 4 1.8733 4.5136 4 125.6995236

20 6

APPENDIX 7

The tables below lists the vibration acceleration values (aRMS) of all the participants

recorded at the vibration platform and at the ankle level with other important details

during the mining boot trials at the high frequency and low frequency vibration profiles.

The table can also be referenced for the associated health risks for the vibration values

recorded at the floor and ankle level for the eight-hour exposure ISO 2631-1 HGCZ.

According to the ISO 2631-1 for the WBV, HGCZ for eight hour duration lies in the

vibration frequency range of 0.45-0.9 m/s2. Based on the guidelines, for exposures below

the zone i.e. below 0.45 m/s2, health effects have not been clearly documented; in the

zone i.e. 0.45 m/s2-0.9m/s2, cautions with respect to potential health risks is indicated and

lastly for the aRMS value above 0.9m/s2, for eight hours duration, health risks are likely

(ISO 2631-1,1997).

The measurement units of the values in the charts are as follows:

• RMS acceleration is in meters per second squared (m/s )

• Dominant Frequency (DF) is in Hertz (Hz)

Subject 1- Power-plate data

S. No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkfc

PEAKAnkle

D.FAnkle

TransBoot

1 a 1 MB 1 XX.95X8 23.93 40 X0.3509 23.8975 40 86.6X

1 a 2 MB 2 24.X402 50.2532 40 XX.0X4X 26.355 40 45.63

X b 1 MB 2 2X.2523 43.2009 40 X2.5987 35.03X7 40 59.28

1 b 2 MB X X2.8323 22.3799 40 8.783X 2X.4907 40 68.45

Subject 1- Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

XaX MB 2 X.60X 4.098X 4 X.4376 4.44X4 4 89.79

1 a 2 MBX X.5633 4.3564 4 X.42X2 3.8976 4 90.9X

X b X MBX X.5829 4.6088 4 X.4388 4.5399 4 90.90

X b2 MB 2 X.4372 4.X528 4 X.329 3.8392 4 92.47

Subject 2 - Power-plate data

S.No.BootType

aR.M.SFloor

PEAKFfoor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB2 13.4071 31.2809 40 8.6978 25.7128 40 64.87

1 a 2 MB1 10.6568 24.3801 40 3.0112 10.4506 63 28.26

l b l MB1 10.5335 22.0301 40 4.2739 13.6019 63 40.57

1 b 2 MB2 11.6149 22.133 40 5.4737 14.7787 63 47.13

Subject 2 - Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB1 1.3743 3.8647 4 1.0762 2.4016 4 78.31

l a 2 MB2 1.2284 3.0373 5 1.031 2.3266 5 83.93

l b l MB2 1.2012 3.193 2.5 1.0287 2.5139 2.5 85.64

1 b 2 MB1 1.2436 3.9816 2.5 1.0802 2.2931 2.5 86.86

Subject 3 - Power-plate data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB1 15.6S84 34.4812 40 10.2782 26.3662 40 65.64

1 a 2 MB2 13.3547 25.5409 40 5.8592 14.8636 40 43.87

l b l MB2 15.4136 37.4037 40 11.9869 32.6207 40 77.77

1 b 2 MB1 14.1292 28.825 40 9.8836 26.7998 40 69.95

Subject 3 - Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB2 1.7841 4.7363 4 1.8075 4.1036 4 101.31

l a 2 MB1 1.7722 4.6565 4 1.8097 4.2279 4 102.12

l b l MB1 1.8807 4.5211 4 1.9454 4.4467 4 103.44

l b 2 MB2 1.796 4.4519 4 1.8876 4.3233 4 105.10

Subject 4 - Power-plate data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB1 14.3329 22.6434 40 12.846S 23.459 40 89.63

1 a 2 MB2 21.603 44.9308 40 19.048 36.2644 40 88.17

l b l MB2 35.6714 55.7028 40 28.2919 46.6615 40 79.31

1 b 2 MB1 35.67 55.4229 40 27.5012 43.424 40 77.10

Subject 4 - Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB2 1.446 3.5705 5 1.3681 3.6217 5 94.61

1 a 2 MB1 1.4345 3.64 5 1.3772 3.4137 4 96.01

l b l MB1 1.4769 3.6378 5 1.4016 3.5461 5 94.90

l b 2 MB2 1.5455 3.777 5 1.3826 3.8097 5 89.46

Subject 5 - Power-plate data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle Trans Boot

l a l MB 2 34.0961 59.5012 40 30.2258 64.475 40 88.6488484

1 a 2 MB 1 35.6153 62.5804 40 32.0499 64.9216 40 89.98913388

l b l MB 1 31.5417 57.0466 40 27.9155 51.0595 40 88.50347318

1 b 2 MB 2 33.4551 56.2471 40 28.0291 51.4603 40 83.7812471

Subject 5 - Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle Trans Boot

l a l MB 1 1.6981 3.7386 4 1.3905 3.3298 4 81.88563689

1 a 2 MB 2 1.548 3.6428 4 1.261 3.3058 4 81.45994832

l b l MB 2 1.5774 4.9783 5 1.2765 3.4922 4 80.92430582

l b 2 MB 1 1.5447 4.1695 5 1.3032 3.4874 4 84.36589629

Subject 6 - Power-plate data

S.No.BootType

aR.M.SFloor PEAR Floor

D.Fflo o r

aR.M.SAnkle

PEAKAnkle

D.FAnUo

TransBoot

l a l MB1 15.582 35.0156 40 6.9997 16.5085 40 44.92

1 a 2 MB2 26.1496 44.5199 40 18.081 40.5504 40 69.14

l b l MB2 18.9585 38.2709 40 16.3363 36.8981 40 86.17

1 b 2 MB1 31.9645 63.7486 40 12.0193 22.14 40 37.60

Subject 6 - Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB2 1.7856 4.2009 4 1.8066 4.4087 4 101.18

1 a 2 MB1 1.0837 6.1004 4 1.9706 6.2396 4 181.84

l b l MB1 2.0265 6.8331 5 2.1593 6.9116 5 106.55

l b 2 MB2 1.6659 4.3082 5 1.6913 4.35 5 101.52

Subject 7 - Power-plate data

S.No.BootType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB1 20.5458 47.8813 40 8.0553 22.551 40 39.21

l a 2 MB2 16.798 37.5985 40 11.9041 27.1753 40 70.87

l b l MB2 15.3626 37.4062 40 11.1509 27.9023 40 72.58

1 b 2 MB1 12.7266 24.4579 40 4.8518 14.9724 40 38.12

Subject 7 - Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB2 1.4425 3.7005 5 1.4883 3.9776 5 103.18

1 a 2 MB1 1.5999 4.0484 4 1.7125 4.6485 4 107.04

l b l MB1 1.6076 4.025 4 1.7509 4.5554 4 108.91

l b 2 MB2 1.5564 4.3057 4 1.6371 4.5372 4 105.19

Subject 8 - Power-plate data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkta

PEAKAnU*

D.FAnUo

TransBoot

l a l MB2 14.946 31.7896 40 8.9246 23.4193 40 59.71

1 a 2 MB1 30.1846 S5.7484 40 10.9106 22.6439 40 36.15

l b l MB1 14.887 31.6071 40 11.8559 24.3169 40 79.64

1 b 2 MB2 12.9701 24.1875 40 8.5225 20.9045 40 65.71

Subject 8 - Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkkt

PEAKAn k it

D.FAnUo

TransBoot

l a l MB1 1.3465 3.3342 5 1.3184 2.9953 5 97.91

1 a 2 MB2 1.2802 3.4159 5 1.2084 3.0261 5 94.39

l b l MB2 1.3708 2.9658 5 1.267 2.9374 5 92.43

l b 2 MB1 1.452 4.7585 4 1.4213 3.6027 4 97.89

Subject 9 - Power-plate data

S.No.BootType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnklo

PEAKAnUo

D.FAnUo

TransBoot

l a l MB1 16.5416 33.695 40I

7.6235 18.3439 40 46.09

1 a 2 MB2 28.4787 22.8368 40 3.1049 9.0522 40 10.90

l b l MB2 18.3872 39.1586 40 5.8686 14.9023 40 31.92

1 b 2 MB1 12.1455 21.0419 40 5.6182 14.067 40 46.26

Subject 9 - Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnUo

TransBoot

l a l MB2 1.1729 4.5722 5 1.1703 4.9895 5 99.78

1 a 2 MB1 1.1048 4.1737 5 1.2518 4.0793 5 113.31

l b l MB1 1.1176 4.9095 5 1.242 4.632 5 111.13

1 b 2 MB2 1.2375 4.7648 5 1.1201 3.7372 5 90.51

Subject 10- Power-plate data

S.No.BootType

aR.M.SFloor

PEAKFleer

D.FFloor

aR.M.SAnUo PEAK ^

D.FAnUe

TransBoot

l a l MB2 13.0678 26.3251 40 8.4862 17.9929 40 64.94

1 a 2 MB1 32.5126 68.9695 40 40.5045 100.2863 40 124.58

l b l MB1 29.2517 54.7208 40 52.3108 112.5447 40 178.83

1 b 2 MB2 14.8487 29.7002 40 13.0469 26.7238 40 87.87

Subject 10- Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnUo

PEAKAnkle

D.FAnkle

TransBoot

l a l MB1 1.4334 4.1496 4 1.5419 3.9988 4 107.57

l a 2 MB2 1.5336 4.4362 4 1.738 4.7196 4 113.33

l b l MB2 1.5966 4.3445 4 1.7357 4.5279 4 108.71

l b 2 MB1 1.5736 4.3962 4 1.7515 4.6323 4 111.31

Subject 11- Power-plate data

S.No.BootType

aR.M.SFloor PEAK floor

D.FFloor

aR.M.SAnkle PEAK Miklo

D.FAnkle

TransBoot

l a l MB1 12.2912 25.8684 40 7.2703 17.4791 40 59.15

1 a 2 MB2 12.772 25.5478 40 5.5564 13.6635 40 43.50

l b l MB2 12.1593 24.7779 40 6.3934 13.4322 40 52.58

l b 2 MB1 11.SSS2 20.8066 40 6.4789 14.8342 40 56.07

Subject 11- Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnUo

TransBoot

l a l MB2 1.6298 3.5717 4 1.7743 4.4473 5 108.87

l a 2 MB1 1.5866 3.6958 4 1.1896 4.8266 S 74.98

l b l MB1 1.5786 3.668 4 1.8562 4.8758 5 117.59

1 b 2 MB2 1.5982 3.9059 5 1.8456 4.3415 5 115.48

Subject 12- Power-plate data

S.No.BootType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnUo

TransBoot

l a l MB1 11.1873 23.1495 40 10.3706 22.084 40 92.70

1 a 2 MB2 13.1846 26.0716 40 11.0813 24.4899 40 84.05

l b l MB2 13.5146 23.3637 40 14.2915 31.1582 40 105.75

1 b 2 MB1 28.5617 48.0822 40 29.0258 57.0893 40 101.62

Subject 12- Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

Raw R.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB2 1.4368 3.6172 4 1.04 (2.12) 3.6014 4 105.80

l a 2 MB1 1.412 3.5381 5 0.94 (1.89) 3.3749 5 102.26

l b l MB1 1.3831 3.4538 5 0.99 (1.96) 3.3182 5 108.42

1 b 2 MB2 1.4496 3.6837 5 0.99 (1.96) 3.1513 5 102.88

Subject 13- Power-plate data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB1 25.0772 51.2103 40 10.066 27.5915 40 40.14

l a 2 MB2 30.107 55.3134 40 26.4831 57.8838 40 87.96

l b l MB2 31.1992 54.8962 40 25.2469 46.8274 40 80.92

l b 2 MB1 32.4357 55.513 40 14.448 26.5006 40 44.54

Subject 13- Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnUo

PEAKAnkle

D.FAnkle

TransBoot

l a l MB2 1.5759 4.1775 4 1.4187 4.476 4 90.02

l a 2 MB1 1.5312 3.8409 4 1.6666 4.1719 4 108.84

l b l MB1 1.5385 3.7297 4 1.6601 4.5834 4 107.90

1 b 2 MB2 1.5201 4.6274 4 1.4176 4.4238 4 93.26

Subject 14- Power-plate data

S.No.BootType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnlde

TransBoot

l a l MB2 23.7982 48.S847 40 26.7481 71.4061 40 112.40

l a 2 MB1 17.8374 39.6199 40 11.0616 34.0022 40 62.01

l b l MB1 14.7419 31.2622 40 9.8732 30.6434 40 66.97

1 b 2 MB2 15.4179 37.1651 40 21.9392 59.2694 40 142.30

Subject 14- Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkte

PEAKAnkle

D.FAnkle Trans Boot

l a l MB1 1.58 4.0264 4 1.614 3.7414 5 102.151899

1 a 2 MB2 1.5666 3.7452 4 1.4976 3.6372 6.3 95.5955573

l b l MB2 1.548 3.6204 4 1.5031 3.6719 6.3 97.0994832

l b 2 MB1 1.5222 3.9866 4 1.6356 4.3512 4 107.449744

Subject 15- Power-plate data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnklo

PEAKAnM*

D.FAnklo

TransBoot

l a l MB1 15.8643 34.6599 40 24.6786 65.6926 63 155.56

1 a 2 MB2 14.1768 29.958 40 7.413 17.5909 40 52.29

l b l MB2 14.5396 31.8643 40 11.7238 21.4739 40 80.63

1 b 2 MB1 14.1373 31.4245 40 9.5693 31.3599 63 67.69

Subject 15- Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkJe

PEAKAnkle

D.FAnU*

TransBoot

l a l MB2 1.4236 4.4583 4 1.6054 5.0084 4 112.77

1 a 2 MB1 1.4026 4.2482 4 1.5127 4.8238 4 107.85

l b l MB1 1.4901 4.2254 5 1.5767 4.525 5 105.81

1 b 2 MB2 1.4677 4.3111 5 1.6705 4.5274 5 113.82

Subject 16- Power-plate data

S.No.BootType

aR.M.SFloor PEAK Floor

D.FFloor

aR.M.SAnid*

PEAKAnkle

D.FAnUo

TransBoot

l a l MB2 14.3421 23.4977 40 19.2052 39.5456 40 133.91

1 a 2 MB1 14.7029 31.432 40 4.1688 11.9472 40 28.35

l b l MB1 15.8334 31.7239 40 5.2662 12.7339 40 33.26

1 b 2 MB2 21.5166 36.4527 40 24.7532 44.7533 40 115.04

Subject 16- Vibration simulator data

S.No.BootType

aR.M.SFloor

PEAKFloor

D.FFloor

aR.M.SAnkle

PEAKAnkle

D.FAnkle

TransBoot

l a l MB1 1.5055 4.887 5 1.7586 4.1555 5 116.81

1 a 2 MB2 1.4579 5.8279 5 1.3896 3.8276 5 95.32

l b l MB2 1.4576 4.2793 5 1.3723 4.0318 5 94.15

l b 2 MB1 1.4369 4.4032 4 1.6227 3.8413 5 112.93