Compared to type I (slow oxidative) skeletal muscle fibers, how are type IIb (fast-glycolytic) skeletal muscle fibers different?
A) Type IIb fibers have more abundant mitochondria.
B) Type IIb fibers fatigue more readily.
C) Type IIb fibers have more abundant myoglobin.
D) Type IIb fibers are smaller in diameter.
E) Type IIb motor units contain fewer fibers per alpha motor neuron.

Question

Quizplus · Accepted Answer

Type IIb fibers are classified as fast-glycolytic fibers, meaning they rely more on anaerobic metabolism for energy production. As a result, they fatigue more readily than type I fibers, which rely on aerobic metabolism. The other options are not true of type IIb fibers.

Compared to Type I (Slow Oxidative) Skeletal Muscle Fibers, How