What is capillarization in the context of exercise physiology?

Capillarization refers to the process of increasing the number of capillaries in a given area, particularly in skeletal muscles, as a response to consistent endurance training. This enhancement of capillary density plays a crucial role in improving the delivery of oxygen and nutrients to the muscles during exercise. As capillary networks expand, the surface area for gas and nutrient exchange increases, leading to improved blood flow and enhanced aerobic capacity. This physiological adaptation helps to meet the higher demands placed on the muscles during physical activity, supporting better overall performance and endurance.

The other choices do not accurately capture the definition of capillarization. A decrease in capillary density contradicts the basic concept of capillarization, while the capacity of muscles to store oxygen refers more to myoglobin content rather than the density of capillaries. Lastly, the total number of blood cells in circulation does not relate to the structural changes within the muscle tissue's vascular network that capillarization entails. Thus, the correct answer emphasizes the critical link between increased capillary supply and enhanced muscle performance during exercise.