In this lab, electrodes wil be placed on the right and left forearms of the subj
ID: 3280626 • Letter: I
Question
In this lab, electrodes wil be placed on the right and left forearms of the subject. The following events will be recorded: The subject clenching (grasping a clench force transducer) using different forces The subject's maximum grip strength will be obtained by the force the transducer measures The subject will clench the transducer with their maximum grip strength and will continue doing so until fatigue level restricts the hand to only 50% of the maximum grip force. The same data will be collect on the non-dominant arm Answer the following questions: 1. What is actually being measured in an EMG? 2. Why is an EMG signal so noisy? 3. Estimate the maximum grip force on the transducer that you think you will be able to grip. Give in units of pounds-force and kilograms-force.
Explanation / Answer
1. EMG measure electrical activity produced by skeletal muscles. It measures the electrical potential generated by muscle cells.
2. The EMG signal can be a bit noisy because of the following reasons:
(i) Noise from tissue rather than muscle that generate electrical signal such as EKG signal.
(ii) Excessive EMG signal amplitude may cause saturation.
(iii) electrical signals from the muscles that are of no interest.
(iv) noise due to relative motion of the senson and the underlying skin
(v) noise from the power lines.
3. Since different muscles have diffrent force associated with it , there is no one transducer that can cover all the muslces. The contractile force generated by single cardiac muscles is of the order of 2 micro Newton while that of a biscep of trainned sportsman is about 1000 N.
4. 10 seconds
5. Higly precise measurments using transducer can be helpful for paralytic patients as this would help the doctors to keep a track on the improvement of its patients.
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