Question

When the intensity of exercise exceeds 75% of VO2 max, which of the following fibers are likely brought into play?

a. Type I
b. Type IIx
c. Type IIa
d. Type Ix

Answer 1

Type IIx fibers are likely brought into play when the intensity of exercise exceeds 75% of VO2 max. They are fast glycolytic muscles that produce powerful, high-tension contractions but fatigue quickly.

Step-by-step explanation:

When the intensity of exercise exceeds 75% of VO2 max, Type IIx fibers are likely brought into play. Type IIx fibers are fast glycolytic muscles that primarily use anaerobic glycolysis to produce powerful, high-tension contractions but fatigue quickly. They have a large diameter, low levels of mitochondria, and are white in color.