Refer to the figure below. IV III Reference: Ref 20-1 What state of muscle activity does this figure represent? Select one: O a. Somewhat contracted O b. Fully relaxed O c. Fully contracted O d. Tetany

Describe the changes that occur in skeletal muscle as a result of endurance training. Include a brief discussion on how endurance training improves acid-base balance during exercise. What physiological benefits may happen for an older adult who begins a progressive resistance-training program?

2. We discussed how muscle spindles allow for precision of movement as a muscle lengthens, and particular muscles which require more precise movements will contain more spindles. In addition to this precision control over muscle length, there are other differences between muscles which enable more precision in how much force is generated. Consider the two graphs below which depict force generated by two different muscles as additional motor units are recruited. Force Muscle A Load Force Muscle B Load a) Describe why the first steps for a low force contraction in both muscles are smaller than the later ones in the context of motor units and force production.

Describe what happens to muscle during atrophy and hypertrophy. List 2 ways that atrophy occurs. List 2 ways that hypertrophy occurs.