Muscle Contraction Lab

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Introduction Throughout the three experiments we completed we looked at muscle strength and muscle fatigue, testing various arm and hand muscles doing different actions. Muscle strength is related to muscle contractions, which is when muscle fibers create tension and shorten the muscle. The number of motor units in a muscle that is being activated is what determines how strong the muscle contraction is. If multiple motor units are being fired continuously then the muscle is being constantly contracted. To begin a muscle contraction, an action potential is created at the neuromuscular junction and moved along the sarcolemma. When it reaches the T tubule, the action potential is sent on the T tubule membrane into the interior of the muscle of…show more content…
One pair of electrodes were placed on the subjects pronator teres muscle and the other pair was placed on the biceps brachii. A fifth electrode was placed on the subject’s abdomen, on the right side. The subject was then asked to put their arm in an arm wrestling position with another person. They were instructed to begin in a neutral position for four seconds, then the subject was asked to put their arm in the winning position for four seconds before returning back to the neutral position for four seconds. Then the subject was asked to put their arm in the losing position for four seconds before returning to the neutral position for two seconds. The subject was asked to complete this cycle two more times while lab scribe recorded the muscle force. For the next part of the experiment “EMGs During an Actual Arm Wrestling Match,” the subject was asked to perform a normal arm wrestling match. For the last part of the experiment “EMGs During an Actual Arm Wrestling Match using Other Muscle Groups,” the subject was once again asked to perform a normal arm wrestling match, except we moved the electrodes on their arm to different muscles to see the difference in force being

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