Which statement is true about the effect of fitness on capillaries in muscles?

Which statement is true about the effect of fitness on capillaries in muscles?

• A. Increases number of capillaries in muscles
• B. Decreases capillary density
• C. Has no effect on capillaries
• D. Eliminates capillaries

Answer: (A)

Endurance fitness promotes the growth of more tiny blood vessels around muscle fibers, a process called capillarization. Regular aerobic work signals the muscles to form new capillaries, increasing the capillary network and the capillary-to-fiber ratio. With more capillaries, oxygen and nutrients diffuse more readily to mitochondria, waste products are removed faster, and the muscles can sustain higher levels of work. This is why aerobic training improves endurance and VO2 max. The idea that fitness would decrease capillary density, have no effect, or eliminate capillaries doesn’t fit with how the body adapts to regular training; capillaries grow rather than disappear or stay unchanged.

Endurance fitness promotes the growth of more tiny blood vessels around muscle fibers, a process called capillarization. Regular aerobic work signals the muscles to form new capillaries, increasing the capillary network and the capillary-to-fiber ratio. With more capillaries, oxygen and nutrients diffuse more readily to mitochondria, waste products are removed faster, and the muscles can sustain higher levels of work. This is why aerobic training improves endurance and VO2 max. The idea that fitness would decrease capillary density, have no effect, or eliminate capillaries doesn’t fit with how the body adapts to regular training; capillaries grow rather than disappear or stay unchanged.