EMG of the Calf Muscle in Bipedal Forward Motion .Jesse Thornburg

2.671 Instrumentation and Measurement

Numerous leg motions, specifically those which involve elevating the heel, require neurological stimulation of the calf muscles. Athletes seek to exercise these muscles by standing exercises, walking, jumping, and running. This study used an electromyographic (EMG) preamplifier to record voltage signals in the calf, specifically looking at the way these signals vary for different states of forward motion. Standing, walking, and running were compared, with the latter two activities being further observed at different inclines. In total, EMG in the calf was recorded over 7 states of bipedal activity. The mean voltage signal was observed to increase with both speed and incline. Increases in speed also caused the signals’ oscillations to become less uniform and less distinct.

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Abstract

Methods

•Mean EMG signal and error increased as forward speed increased. Increasing speed also made the signal less distinctly sinusoidal, with the frequency of oscillation becoming less pronounced.

•The mean EMG also increased with incline. The change in sinusoidal behavior, however, was less pronounced than with increasing velocity. This trend merits further study.

•Comparing test subjects’ EMG showed that as they increase velocity, those who run regularly have lower EMG increase than those who do not run. No relation tying EMG increase with a running regimen was apparent with changing incline. This phenomenon merits further study.

Conclusions

Dec 3, 2009

Speed Results

1. Gray, Henry. Anatomy of the Human Body. Philadelphia: Lea & Febiger, 1918; Bartleby.com, 2000. [10/28/09]. <www.bartleby.com/107>.

2. Hunter, I.W. and B.J. Hughey. “Uncertainty Analysis.” 2.671 Measurement and Instrumentation, Class Notes. MIT Mechanical Engineering Department.

< https://wikis.mit.edu/confluence/display/2DOT671/ >.

ReferencesAcknowledgements

Thanks to Professor Matthew Lang, Dr. Barbara Hughey, Dianna Cowern, Ian Tracy, and Luke Thornburg for their help on the tests.

• Mammalian muscles flex or extend based on the voltage signals transmitted from the brain by neurons. • Electromyography (EMG) measures these signals, here with a surface electrode on the gastrocnemius muscle of the calf. • The gastrocnemius receives signals from the 1st and 2nd sacral nerves1.

Modes of Activity

http://jmm.consultantlive.com/display/article/1145622/1412245?verify=0

Incline Results

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State 1 State 2 State 3 State 4

Flat 6% incline 9% incline

•Errors calculated with a 95% confidence interval and propagation of errors2.

Test Subjects

1. Standing, flat2. Walking, flat (1.0 mph)3. Jogging, flat (5.5 mph)4. Running, flat (8.0 mph)5. Walking, uphill 6 % (1.0 mph)6. Walking, uphill 9 % (1.0 mph)7. Jogging, uphill 9 % (5.5 mph)

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1. Runs 6 days/week (9.5 mph, 45 min/run)

2. Runs 3 days/week (8.5 mph, 30 min/run)

3. Does not run regularly

- All test subjects were healthy male

college students, 18-20 years old

0 10 20 30 40 50 60 70 80 900 15 30 45 60 75 90Time (sec)

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Still 1 mph 5.5 mph 8 mph

V V

Baum’s “Canonical” Oz Books

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