第20页 | The Big Book of Endurance Training and Racing | 阅读 ‧ 电子书库

The Aerobic System

The conversion of fat to energy—fat burning—takes place in the aerobic muscles (these are sometimes called slow-twitch or red muscle fibers). Humans are well endowed with these muscles and they are the ones depended upon during activity of longer duration—they can function well for many hours and even days in a well-trained athlete. Aerobic muscles have other important functions too. Three important ones include:

 

 

Physical support for our bones and joints. They help prevent and correct mechanical imbalances that cause injuries.Circulation. Literally miles of blood vessels help bring much-needed, nutrient-rich blood to the muscles, bringing oxygen, vitamins, minerals, hormones, and so forth, and removing other products such as lactate and carbon dioxide.Immune function. This helps our body’s natural defense control excess free radicals to prevent and recover from illness, and help regulate inflammation.