How does aerobic exercise affect muscle composition?

Aerobic exercise primarily enhances the functional capacity of muscles rather than significantly altering their size or strength in the same manner that resistance training does. One of the key adaptations to aerobic exercise is the increased density of mitochondria within muscle fibers. Mitochondria are the powerhouse of the cell, responsible for energy production through aerobic metabolism, which uses oxygen to convert fuel sources like carbohydrates and fats into usable energy.

In addition to mitochondrial density, aerobic exercise also leads to an increase in the number of capillaries surrounding the muscle fibers. This enhanced capillary network improves blood flow, delivering more oxygen and nutrients to the muscles during activity and facilitating better waste removal. These adaptations are crucial for improving endurance, as they allow muscles to perform more work over extended periods.

While some forms of aerobic exercise can lead to slight increases in muscle endurance, the primary benefits are related to efficiency and stamina rather than increases in muscle size or strength. Therefore, increased mitochondrial and capillary density is a hallmark of the positive effects of aerobic exercise on muscle composition.