Electromyography Lab

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Motor unit recruitment is the sequential activation of motor units to perform a certain task. In this lab we examined motor unit recruitment and muscle fatigue by electromyography (EMG) with dynamometry (DYN). When the motor unit in the muscle is activated signals are then generated, which result in muscle contraction. The impulse generated are a bit weak, yet can still be detected by the electrodes, EMG and is coupled by a measurements of power, DYN. When all the motor units reach its maximum strength the muscles will fatigue. Finally, the objectives of this lab were to determine the maximum clench strength for the right and left hand. To observe, record and correlate motor unit recruitment with increase power of skeletal muscle contraction. As well, as to record the force produces by the clenching muscles and integrated EMG during fiber recruitment and inducing fatigue.

The lab equipment included a hand dynamometer, electrodes lead set and the computer program. We placed three electrodes to each forearm of the subject. First we began with the subject’s dominant forearm. We recorded a cycle clench-release-wait, holding for two seconds and releasing for two seconds before beginning the next cycle. This is when the subject began to increment force as assigned (10, 20, 30 kg). Then the subject clenched the hand dynamometer with maximum force until the maximum displayed forced on the screen decreased to more than 50% then we suspended the recording. Then we connected the electrodes to the subject’s non-dominant forearm. Next we repeated the same steps as mentioned for the subject’s dominant forearm. Finally, we analyzed the data by using the I beam cursor to measure the CH 1 (Force) mean, CH 3 (EMG) p-p and CH 40 (integrated EMG) mean for both the dominant and non-dominant forearm fore increasement segments. Finally, we measured the CH1 value and CH 40 delta T value for both forearms using the maximum force segment. We then calculated...
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