Correct Response: D. After vigorous exercise, a cool down gradually reduces the intensity of movement, which aids in maintaining the flow of blood back to the heart for recirculation and keeps blood from pooling in the lower limbs. Muscles that are warm from exercise are in an optimum state for effective stretching, which may decrease the buildup of lactic acid and help prevent muscle cramping and stiffness. A cool down would gradually slow the metabolic rate (A) and does not significantly affect carbohydrate and glucose levels (B) or growth hormone levels (C).
