Which statement about fast-twitch and slow-twitch fibers is true?
A) In skeletal muscle, the most important factor determining the proportion of fast- and slow-twitch fibers is physical training.
B) Aerobic training increases the oxidative capacity of intermediate fibers.
C) A single muscle cell may contain fast- and slow-twitch fibers.
D) Fast-twitch fibers fatigue slowly.
E) Champion sprinters are likely to have a high proportion of slow-twitch fibers in their legs.

Question

Quizplus · Accepted Answer

Aerobic training enhances the oxidative capacity of intermediate fibers, making them more efficient at using oxygen and improving endurance. Fast- and slow-twitch fibers are determined primarily by genetics, not training. A single muscle cell cannot contain both types of fibers; it is either fast-twitch or slow-twitch. Fast-twitch fibers fatigue quickly, not slowly. Champion sprinters would have a high proportion of fast-twitch fibers, not slow-twitch fibers, to allow for quick, powerful movements.

Which Statement About Fast-Twitch and Slow-Twitch Fibers Is True