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J Int Acad Phys Ther Res 2012; 3(1): 345-411ISSN 2092-8475

www.iaptr.orghttp://dx.doi.org/10.5854/JIAPTR.2012.3.1.364

Different from other animals, humans have footarch as they walk upright. At the moment, peoplefeel less fatigue in walking only when arch takesproper form as it balances the strength of muscles.Gi et al. suggested that walking is one of essentialpart of our daily lives as it is within bounds to saythat people lead their whole lives walking and it is abasic of all exercise(1). As seen above, walking is amovement that accompanies integrated reflection ofnumerous skeletal muscles and nerves(2, 3). Due towrong shoes, posture, and walking in modern days,however, there is gradual increase in illness followedby the deformation in foot arch and its effect onwalking pattern. About 5% of all Koreans have flatfoot and it is either natural or acquired(4). Flatfootcan be considered as one of the deformations in footarch. In here, flatfoot refers to the collapse of innerfoot arch and clinically it becomes closer to theground compared to normal(5).Also, externally, it presents trait such as internal

rotation of talus, decrease in height of inner longitu-dinal arch, and abduction and rotation in forefoot(4).At themoment, there may be a change in themech-anism of movement followed by anatomical changein tarsal bone and it may bring about secondarydeformation called degenerative arthritis(6). The bal-ance of body is broken when there is the collapse ordeformation in foot arch as it impedes proper walk-ing. While walking, the pronation state that occursduring initial stance phase is delayed or lengthenedcompared to normal range. At the moment, flatfootsuffers from pain in bumpy road. Also, the weightload is directly passed onto the ground with the dif-ficulty in toe off followed by the weakening of gas-trocnemius and soleus(7). As seen above, foot is aorgan that secures the stability by balancing thebody for the maintenance of upright position ofhuman body. In regards to calf muscles surroundingthe ankle, its activity changes all the time accordingto the position of pendulum structure and state ofsupporting surface(8). Walking can be defined as anexercise thatmoveswhole bodybymovingbodyparts

The analysis of Lower Limb Muscle Activity and Motion Analysis

according to Normal Foot and Flatfoot during Walking

INTRODUCTION

The purpose of this study was to analyze lower limb muscle activityand 3D motion analysis according to change foot arch height duringwalking. We selected 9 young and healthy people who have beennormal foot. And we selected 7 young and healthy people who havebeen flatfoot. So, people were divided into 2 groups and walked plat-form during 2 minutes twice for checked by 3D motion analysis.These data were characterized by EMG measurements of three mus-cles(tibialis anterior, medial and lateral gastrocnemius) while theywere walking. The collected data were analyzed by Independent ttest using the SPSS statistics program(Ver 12.0). In foot arch change,there were no significant difference in three muscles 3D motionanalysis also found that there were no significant difference in jointangles. In this study was to analyze lower limb muscle activity and 3Dmotion analysis according to change foot arch, but there were nosignificant difference in 6 muscles neither joint angles.

Key words: Flatfoot; EMG; 3D Motion Analysis; Foot Arch

Jung Gyu Yoona, Kyung Tae Yooa,Ji Hong Leea, Jae Min Parka,Kyung Ok Minb, Jung Hyun Choia

aNamseoul University, Cheonan; bYonginUniversity, Yongin, Korea

Received : 21 November 2011Accepted : 18 February 2012

AAddddrreessss ffoorr ccoorrrreessppoonnddeenncceeJung Hyun Choi, PT, Ph.DDepartment of Physical Therapy, uni-versity of Namseoul 91, Daehak-roSeonghwan-Eup, Seobuk-Gu, Chonan331-707, Korea.Tel: +82-41-580-2534E-mail: rightmind@nsu.ac.kr

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The analysis of Lower Limb Muscle Activity and Motion Analysis according to Normal Foot and Flatfoot during Walking

in stages and maintaining the speed toward certaindirection. In here, a walking pattern that representsthe diversity in people differs a lot in each individ-ual(9). In order to conduct quantitative analysis onwalking, it is necessary to grasp objective walkingvariables and various methods from simple observa-tion to three dimensional motion analysis based onoptical engineering technology are being used(10).Flatfoot patients who experienced the symptomsduring general walking has limited means or tools tocompensate for the incompetence(11). Various studieson flatfoot are being conducted including the effectof insole type of normal foot and flatfoot while walk-ing or running, difference in sole load between nor-mal foot and flatfoot when performing exercisetask(12, 13). In addition, studies such as the distribu-tion of sole pressure while walking or influence ofshoes with curved soles on the change in static pos-ture and EMG of calf are continuously being con-ducted as the emphasis is put on the form of walkingnowadays(8, 14). In preceding studies, ankle jointwas measured in accordance with the plan by divid-ing the walking cycle. In regards to the muscleactivity, the difference in activation was also com-pared in accordance with walking cycle. As a result,the activation of tibialis anterior muscle was pre-sented to be high in flatfoot group from initial tomiddle stance phase and other muscles presentedweak muscle activity compared to it. Also, flatfootgroup displayed bigger ankle movement in plantarflexors compared to normal group in toe off and itdisplayed significant difference(11). However, it has alimitation that only difference in movement fromknee joint and ankle joint can be presented. Therefore, the purpose of this study lies in analyz-ing the movement in joint facet of lower limb andexamining the difference in muscle activity of lowerlimb based on the change in height of foot arch sub-jecting normal foot and flatfoot. In other words, thedifference between groups regarding each joint inlower limb and difference in the degree of rotation inpelvis while walking were measured.

The subjects of this study is 20 students in 20's whoare attending N university located in Cheonan-si.Although number of subjects for both normal groupand flatfoot groups was 10, 1 subject in normalgroups and 3 subjects in flat foot group dropped out

during the experiment due to personal reasons.Therefore, total 16 subjects including 9 subjects innormal group and 7 subjects in flat foot group par-ticipated in this experiment. They have listened tothe explanation on the experiment process, had noproblem performing the experiment, and had volun-tarily agreed to participate in the experiment. Also,random selection was carried out from those who donot have skeletal muscular disease in lower limb andthose who received surgical operation due to theinjury or lesion in lower limb were excluded.

MMeeaassuurreemmeenntt ttoooollExperiment equipment used in this study is as fol-lowing(Table 1).

FFoooott ttyyppeeForm of foot arch was looked into by printing footstamp and examining through foot printer. 20 sub-jects who participated in the experiment gentlyplaced right and bare foot on the foot printer andthey lifted their feet after staying for 3 seconds afterexerting full weight(15). Foot print interpretationmethod using foot printer is as following(Fig 1).

Subjects

Measurement

Procedure

METHODS

EMG

Motion capture

Electronic scale

Pocket EMG

Smart-E

150A

Italy/ BTS

Italy/ BTS

Korea/ CAS

Product nameName of equipment Manufacturer

TTaabbllee 11.. Measurement tool

①①

AA HHBB

②②

③③⑦⑦

⑤⑤

④④

⑧⑧

⑥⑥

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J.G. Yoon, K.T. Yoo, J.H. Lee, et al.

AAnnaallyyssiiss oonn wwaallkkiinngg ppaatttteerrnn uussiinngg mmoottiioonn ccaappttuurreeIn order to numerically measure walking pattern inregards to the change in height of foot arch ofexperimentee, it was measured using three dimen-sional motion capture. Chief researcher attached themarker of motion capture to anterior superior iliacspine, hip joint, knee joint, lateral epicondyle of foot,and fifth metatarsal bone of both sides. Motionswere measured in three dimension regarding mark-ers attached to each joint facet. Data regarding theangle of hip joint, knee joint, and ankle joint whilewalking and the size of motion when pelvis is rotat-ing toward left and right(x axis and y axis) wereexamined. Angle of hip joint was measured based onthe attachment on anterior superior iliac spine andknee joint facet in same side, angle of knee joint wasbased on the attachment on hip joint facet and later-al epicondyle of foot, and angle of ankle joint wasmeasured based on the attachment on knee jointfacet and joint facet of fifth metatarsal bone. Inregards to the rotation of pelvis, a virtual point thatis in same straight line as sacrum was taken as thestandard and the distance anterior superior iliacspine moved toward x axis and y axis from thatpoint was measured. Then, the difference between

two groups were examined. Under the supervision oftwo specialists, the location of a virtual point wasset. Also, angle of all joints was measured based on asingle walking cycle. In order to exclude intentionalwalking, the experiment was conducted withoutinforming the experimentee about the time of meas-urement and mean data was acquired by measuringtwice per each person.

MMeeaassuurreemmeenntt ooff eelleeccttrroommyyooggrraamm uussiinngg EEMMGGIn order to examine the difference in the activity oflow limb muscles while walking between two groups,pocket EMG was used. In order to minimize the errorin experiment, experimentee wore shorts. For theparts to attach electrode, the removal of hair andsterilization were carried out. At the moment, elec-trode was continuously attached by the chiefresearcher for the unity. Lateral gastrocnemius,medial, and tibialis anterior were taken as subjectsthat have influence on walking. An electrode wasattached to the belly of each muscle.

Physical traits of 16 experiment participants wereanalyzed with descriptive statistics using SPSS(Ver12.0) in this study. Muscle activity of normal groupand flatfoot group and mean and standard deviationin accordance with the difference in joint angle whilewalking was calculated. Then, normal distributionwas confirmed through K-S test. Comparativeanalysis on the difference in angle and muscle activ-ity of each joint was carried out with independent t-test and all statistical significance level was set as.05 in this experiment.

The characteristics of the subjects are listed inTable 2.

Data Analysis

General Characteristics of the Subjects

RESULTS

FFiigg.. 11.. Interpreting manners of sole print

①②③④⑤⑥

⑦⑧

The far left outside point of first metatarsal headThe far left outside point of calcaneusThe far right outside point of 5th metatarsal headThe far right outside point of calcaneusThe center of balance of 2nd toeThe crossing of line A and line B- line A: the direct line, linking ① and ②- line B: the direct line, linking ③ and ④- line H: the direct line, linking ⑤ and ⑥The longitudinal length of foot archThe transverse length of foot archIf the foot arch is located in the part of HA, it is anormal foot and if located in the part of HB, it isa flat foot. When there is no shape of foot arch, itis a pes cavus foot(high arch foot).

Height(cm)

Weight(kg)

Age(yrs)

Foot size(mm)

172.22±9.40

58.44±6.46

22.44±2.19

256.11±12.94

168.57±8.00

60.00±8.50

22.14±1.77

252.14±11.13

.426

.683

.771

.529

Physical traits Normal foot(n=9) Flatfoot(n=7) p

TTaabbllee 22.. General characteristics of the subjects (Mean±SD)

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The analysis of Lower Limb Muscle Activity and Motion Analysis according to Normal Foot and Flatfoot during Walking

There was no significant difference in lateral and

medial gastrocnemius, tibialis anterior based on nor-mal foot and flatfoot (p>.05)(Table 3).

Comparison on Muscle Activity of Left·RightSide of Three Muscles Based on Foot Type

There was no significant difference in angle of hip,

knee, and ankle joint while walking based on normalfoot and flatfoot(p>.05)(Table 4).

Comparison on Angle of Left·Right AnkleBased on Foot Type

There was no significant difference in motion

regarding left and right of pelvis based on normalfoot and flatfoot(p>.05)(Table 5).

Comparison on Difference in Motion of Pelvis

Right lateral gastrocnemius

Left lateral gastrocnemius

Right medial gastrocnemius

Left medial gastrocnemius

Right tibialis anterior

Left tibialis anterior

.044±.025

.034±.012

.061±.028

.089±.069

.052±.014

.050±.015

.025±.009

.028±.010

.060±.023

.065±.028

.043±.023

.056±.029

2.110

1.078

.125

.938

.859

-.496

.059

.299

.902

.368

.411

.633

Mean±SD

Normal foot

Mean±SD

FlatfootMuscle t p

TTaabbllee 33.. Comparison on muscle activity of 6 muscles based on group (mV)

Right hip joint

Left hip joint

Right knee joint

Left knee joint

Right ankle joint

Left ankle joint

126.94±22.05

127.63±15.82

32.77±11.49

20.18±8.88

93.11±11.13

90.50±10.48

115.31±25.30

127.95±19.80

27.31±14.59

24.52±8.35

92.86±4.89

87.23±7.59

.964

-.035

.814

-1.003

.061

.724

.354

.972

.433

.334

.952

.481

Mean±SD

Normal foot

Mean±SD

FlatfootJoint t p

TTaabbllee 44.. Comparison on angle of each joint between group (Degree)

From ｘ axis

From ｙ axis

807.12±484.09

8.36±3.10

688.36±440.70

8.19±4.45

.512

.084

.617

.935

Mean±SD

Normal foot

Mean±SD

Flatfoott p

TTaabbllee 55.. Comparison on difference in motion of pelvis (mm)

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J.G. Yoon, K.T. Yoo, J.H. Lee, et al.

The purpose of this study was to compare the mus-cle activity of lower limb muscle(tibialis anterior,medial and lateral gastrocnemius) followed by thecollapse of foot arch and the angle of each joint whilewalking in order to examine the change in the muscleactivity of lower limb and walking pattern based onthe change in the height of foot arch. As a result ofcomparing the muscle activity while walking betweennormal foot group and flatfoot group with the col-lapse of foot arch in accordance with the height offoot arch, there was no significant difference in all ofthree muscles(tibialis anterior, medial and lateralgastrocnemius). However, it may be different whetheror not to select people who have experienced thesymptoms of skeletal muscular disease as experimentsubject. Subject may not have experienced skeletalmuscular disease as there is the difference in degreeeven through subject may physically belong to flat-foot group(5). In addition, Chung et al. suggested thatthere is correlation between the collapse of foot archand experience of symptom although many flatfootpatients complain about the pain after strenuouswork(6). Therefore, it can be considered that no evi-dent significance has been found as there are subjectswho do not have difficulty in daily lives regardless ofhaving flatfoot. In the study of Kim the correlationbetween age, weight, height, height of heel, change inshoe size, and occupation of normal group and flatfoot group was examined(15). As a result, there wassignificant difference in that there are more flatfootwith the increase in age. Although there was achange in height of foot arch followed by physiologi-cal change caused by aging of tissue, muscle and oth-ers with the increase of age, there was no differencerelevant to physiological aging as the subject of thisstudy was in their 20's. Although there was no statis-tically significant difference in preceding studies,other variables presented significant trend thus indepth study on flatfoot group seems to be necessary.As a result of looking into the difference in the traitof physical strength between normal foot and flatfootin the study of Sun et al., there also was not signifi-cant difference in regards to the muscle strength ofknee(16). This study also taken subject who did notexperience skeletal muscular symptom and this isbelieved to be the reason why there was no statisticaldifference. In study of Kim et al. as a result of ana-lyzing the change in the range of joint motion foreach walking cycle with the use of three dimensionalmotion capture, mean joint motion angle for hip joint

was smaller in normal foot group compared to flatfootgroup and that of knee joint and ankle joint was big-ger in normal foot group compared to flatfoot groupin initial stance phase(17). Although it did not displaystatistically significant difference, there was a differ-ence in angle based on the change in height of footarch thus it presented result different from thisstudy. Although this study was carried out subjectingcertain age group that is 20's, as a result of analyzingthe change in the angle of each joint that differs dur-ing normal walking with the increase of age by meas-uring the walking of various age groups in the studyof Chung et al. and others, significant difference wasconfirmed as there was the increase in the bending ofhip joint and knee joint in stance phase(18). In thefuture study, analysis on the walking of flatfoot basedon age shall be carried out. This study has a limita-tion for generalization as there were only 16 subjectsand walking was performed in small space that waslab. Also, although there are various variables inwalking, the experiment was conducted only on mus-cle and joint among them. In the future, studies onthe difference in muscle activity between flexibleflatfoot and rigid flatfoot shall be carried out. Also,one of typical traits of flatfoot is the rotation of sup-porting surface of heel bone toward outside caused bythe weight support line of leg and it is called as val-gus(19). Therefore, the study on the deformation ofvalgus and varus followed by the collapse of foot archor the study on walking posture shall be carried out.

The purpose of this study was to examine the dif-ference in the muscle activity of lower limb andangle of each joint in accordance with the height offoot arch by requesting normal foot and flatfoot stu-dents of N university in their 20's to walk certaindistance. There was no significant difference as aresult of comparing muscle activity of six muscles inaccordance with the height of foot arch. Also, therewas no significant difference in the angle of lowerlimb examined through motion capture. The resultdifferent from preceding studies came out due to thefact subject was flatfoot who did not experienceskeletal muscular disease, walking in small lab isdifferent from actual walking, and there was onlysmall number of experimentee that was 16. As thisstudy has various limitations, future studies regard-ing such limitations shall be carried out.

DISCUSSION

CONCLUSION

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The analysis of Lower Limb Muscle Activity and Motion Analysis according to Normal Foot and Flatfoot during Walking

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