Biofeedback System for Improved Athletic Training

ECE-498Matt Statton

Advisor: Professor Hanson

Goals of athletic training◦ Muscle hypertrophy through stimulation

Muscle fatigue during a specified repetition range Maximum motor unit recruitment inducing muscle

hypertrophy Benefits of effective training

◦ Increased results◦ Injury prevention

Many people do not know how to properly fatigue their muscles◦ Personal trainers

Introduction

How it works◦ Raises awareness of unconscious physiological

activities◦ Control◦ Adjustment

Uses◦ Anxiety and stress◦ Hypertension◦ ADHD

Biofeedback

Electrical signals produced by muscles can be used as an indicator of muscle fatigue

Giving users the ability to recognize their level of muscle fatigue will lead to improved athletic training◦ Maximizing muscle fatigue◦ Decreasing injury

Project Proposal

Measure electrical signals from muscles

Analyze signal to determine level of muscle fatigue

Determine threshold at which muscle fatigue occurs

Provide feedback response to user

Design Requirements

Measure electrical signals from muscles◦ Electromyography

Intramuscular vs. surface electromyography Cost effectiveness Measurement accuracy

Design Requirements

Electromyography

Figure 1: Electromyogram from http://www.dataq.com/images/article_images/emg1.jpg

Measure electrical signals from muscles◦ Electromyography

Analyze signal to determine level of muscle fatigue◦ Analog-to-digital conversion◦ Measure absolute and relative maximum

amplitudes of signal Determine threshold at which muscle

fatigue occurs Provide feedback response to user

Design Requirements

Electromyograph Important components

◦ MAX666CPA Voltage Regulator

◦ LT1494 operational amplifier, A = 1 Provides virtual ground at

Vcc/2◦ INA106 differential

amplifier, A = 10 High common-mode

rejection ratio

Figure 2: Electromyograph circuit based on circuit diagram from http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2005/bsm24_ajg47/website/website/index.htm

LPKF ProtoMat C20S Circuit Board Plotter

Circuit Creation

Figure 3: LPKF Circuit Board Plotter from http://www.lpkf.com/_images/757-lpkf-protomat-h100.jpg

EagleCAD

Figure 4: EagleCAD schematic of electromyograph circuit

Figure 5: EagleCAD board file created from schematic

CircuitCam / BoardMaster

Figure 6: CircuitCam circuit board diagram Figure 7: BoardMaster circuit board diagram

Printed Circuit

Figure 8: Front of printed circuit board Figure 9: Back of printed circuit board

Analyze signal to determine level of muscle fatigue

Determine threshold at which muscle fatigue occurs

Provide feedback response to user

Design Requirements

Silicon Labs C8051F020 microcontroller◦ On-board analog-to-digital converter

ADC0 = 12-bit ADC1 = 8-bit

◦ Programmable in C

Electromyograph Signal Analysis

Electromyograph Signal Analysis

Figure 10: Flow chart of electromyograph signal analysis program

Electromyography

Figure 11: Contraction and relaxation of muscles of the upper arm from http://www.zoodu.com/uploads/images/2006-08-10/vlt9QAl2A5.jpg

Results

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 12.46

2.465

2.47

2.475

2.48

2.485

2.49

2.495

2.5

2.505

Vol

tage

(V)

Time (s)

Electromyogram of Relaxed Muscle

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 12.3

2.35

2.4

2.45

2.5

2.55

2.6

2.65

2.7Electromyogram of Fully Contracted Muscle

Time (s)V

olta

ge (V

)

Figure 12: Electromyogram of relaxed biceps muscle (Range = 30 mV)

Figure 13: Electromyogram of fully contracted and relaxed biceps muscle (Range = 250 mV)

Results

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 12.35

2.4

2.45

2.5

2.55

2.6

Time (s)

Vol

tage

(V)

Electromyogram of Slightly Contracted Muscle

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 12.3

2.35

2.4

2.45

2.5

2.55

2.6

2.65

Time (s)V

olta

ge (V

)

Electromyogram of Fully Contracted and Slightly Contracted Muscle

Figure 14: Electromyogram of slightly contracted and relaxed biceps muscle (Range = 130 mV)

Figure 15: Electromyogram of fully contracted, slightly contracted, and relaxed biceps muscle

Signal processing More sophisticated user interface

◦ LCD screen◦ Buttons◦ Threshold calibration◦ Low battery indicator

Electrode leadwire connectors◦ FDA regulations

Continuing Work

The 8051 microcontroller is not yet accurately measuring absolute and relative maximum amplitudes of the signal

Electrical signals were successfully measured using surface electromyography

Continuing work will be done to successfully analyze the signal and provide users a feedback response based on muscle fatigue

Conclusions

Professor Hanson

Professor Hedrick

Ben Bunes

Acknowledgements

Association for Applied Psychophysiology and Biofeedback. 4 June 2008 <http://www.aapb.org/i4a/pages/index.cfm?pageid=1>.

Gariety, Arthur and Madoff, Benjamin. ECE 476 Final Project: Wireless Electromyograph. 13 November 2008 <http://instruct1.cit.cornell.edu/Courses/ee476/FinalProjects/s2005/bsm24_ajg47/website/website/index.html>.

U.S. National Library of Medicine, National Institutes of Health. Electromyography. 4 June 2008 <http://www.nlm.nih.gov/medlineplus/ency/article/003929.htm>.

http://www.dataq.com/images/article_images/emg1.jpg

http://www.lpkf.com/_images/757-lpkf-protomat-h100.jpg

http://www.winning.co.za/images/exImage6.jpg

http://www.zoodu.com/uploads/images/2006-08-10/vlt9QAl2A5.jpg

Bibliography

Questions?