A Fast-Twitch Muscle Fiber

Question

A fast-twitch muscle fiber
A) uses ATP quickly in short, fast contractions.
B) has many capillaries.
C) is rich in myoglobin.
D) works aerobically.
E) All of the answer choices are correct.

Accepted Answer

Fast-twitch muscle fibers rely mainly on anaerobic metabolism and use ATP quickly in short, fast contractions. They do not have many capillaries and are not rich in myoglobin, which is found in slow-twitch muscle fibers that work aerobically.