Jack, a student In BIO 131, is the subject for this lab and has his EMG recorded

Question

Jack, a student In BIO 131, is the subject for this lab and has his EMG recorded during a maximal contraction, lo achieve a maximal contraction, he must lift 45 pounds. Six months later, after working out steadily and maintaining a healthy diet, Jack?s muscles are notably bigger. He decides to try to elicit a new maximal contraction (and record the EMG), and is now able to lift 60 pounds. Questions: 1. Compare the [MG recordings for Jack?s maximal contraction before and after his 6 month training sessions. Circle the correct answer below: a) The EMGs will have the same amplitude b) The before EMG will have a larger amplitude c) The after EMG will have a larger amplitude 2. (3 Points) After his muscle growth, what would you expect Jack?s EMG to look like if he lifted 45 pounds as he did before? Explain your answer in terms of motor unit recruitment. 3. (3 Points) Why were Jack?s muscles notably bigger after his 6 month training period? What caused the increase in muscle size?

Explanation / Answer

1. c. the after EMG will have larger amplitude

2. after the growth of his trained muscles, the person would have effortlessly lifted the 45 pounds weight.

As a motor unit is one motor neuron and all of the muscle fibers it innervates. When a motor unit fires, the impulse (called an action potential) is carried down the motor neuron to the muscle. The area where the nerve contacts the muscle is called the neuromuscular junction, or the motor end plate. After the action potential is transmitted across the neuromuscular junction, an action potential is elicited in all of the innervated muscle fibers of that particular motor unit. The sum of all this electrical activity is known as a motor unit action potential (MUAP). This electrophysiologic activity from multiple motor units is the signal typically evaluated during an EMG. The composition of the motor unit, the number of muscle fibres per motor unit, the metabolic type of muscle fibres and many other factors affect the shape of the motor unit potentials in the myogram.

3. As Jack workrd out more and trained more the muscles in that area where more energy is being burnt up will increase the the mitochondrial content, as the need for ATP is more. the fat gets burtn up and the loose muscles get toned, here basically fat is getting replaced by muscle which is healthy.Besides, training teaches the person to voluntarily take control of his muscles under training.

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