One of the primary reasons that one individual is faster in a 50-meter sprint than another is a. a greater number of muscle fibers of smaller diameter. b. more oxidative fibers in the lower limb muscles. c. an enhanced ability to deliver oxygen to the muscles. d. a greater percentage of fast-twitch fibers in the lower limb muscles.

The stage of rigor when the LEAST fluid will be absorbed by the muscle tissues is:     A. primary flaccidity   B. during full firmness   C. after the release of rigor (secondary flaccidity)   D. none of the above

Which of the following is an effect of training on the oxidative system?   A. It increases vascularization within the muscles.   B. It increases the number and size of mitochondria within the muscle-fibers.   C. It increases the activity of the enzymes involved   D. all of the above

What is the physiological mechanism that produces a quick and efficient skeletal muscle response to an external stimulus?   A. voluntary motor commands from the brain   B. temporal and spatial summation   C. sensory nerve input to the brain   D. spinal reflex arc   E. endocrine secretory response

Which of the following statements relating to the developmental aspects of muscles is false? a. All muscle tissue types arise from myoblasts b. Skeletal muscles become amitotic while smooth muscles regenerate throughout life c. Sarcopenia begins by age 30 and is irreversible d. Body strength per unit muscle mass is the same in both sexes  e. none of the above   Which of the following structures is located in the head region of the thick filament myosin? a. actin binding site b. ATP binding site c. ATPase enzyme d. all of the above e. none of the above