Question

Relative to slow-twitch fibers, fast twitch fibers are likely to exhibit which property?

A) greater Ca2+ pumping activity
B) increase capillary density
C) more mitochondria
D) higher levels of oxygen-binding proteins

Answer 1

Fast-twitch muscle fibers contain fewer capillaries and mitochondria, while slow-twitch fibers have more capillaries, mitochondria, and myoglobin.

Step-by-step explanation:

Fast-twitch muscle fibers contain fewer capillaries and mitochondria and less myoglobin. They can contract rapidly and powerfully but fatigue quickly. In comparison, slow-twitch fibers are dense with capillaries, rich in mitochondria, and have more myoglobin. They can carry more oxygen and sustain aerobic activity for longer.