Endurance training adaptations: capillarization.

Endurance training adaptations: capillarization.

• A. Decreased capillarization
• B. No change in capillarization
• C. Decreased capillarization with increased VO2max
• D. Increased capillarization in muscles

Answer: (D)

Endurance training promotes angiogenesis in skeletal muscle, increasing capillary density around muscle fibers. This enhanced capillarization shortens the diffusion distance for oxygen from the blood to the mitochondria, increases the surface area for gas exchange, and improves delivery of oxygen and nutrients to working muscles. As a result, maximal oxygen uptake (VO2max) and aerobic endurance improve because muscles can extract and utilize more oxygen during exercise. Decreasing or not changing capillarization would limit oxygen delivery and not reflect the typical adaptations to chronic aerobic training, so the observed change is an increase in capillarization in muscles.

Endurance training promotes angiogenesis in skeletal muscle, increasing capillary density around muscle fibers. This enhanced capillarization shortens the diffusion distance for oxygen from the blood to the mitochondria, increases the surface area for gas exchange, and improves delivery of oxygen and nutrients to working muscles. As a result, maximal oxygen uptake (VO2max) and aerobic endurance improve because muscles can extract and utilize more oxygen during exercise. Decreasing or not changing capillarization would limit oxygen delivery and not reflect the typical adaptations to chronic aerobic training, so the observed change is an increase in capillarization in muscles.