Why are slow-twitch muscles dark?
A) They have many more myofibrils per motor unit than fast-twitch fibers.
B) They are designed for strength and explosions of energy.
C) They need less blood than fast-twitch fibers.
D) They contain myoglobin.
E) They have fewer mitochondria.

Question

Quizplus · Accepted Answer

Slow-twitch fibers are dark because they contain myoglobin, the respiratory pigment found in muscle cells.

Why Are Slow-Twitch Muscles Dark