Endurance training is physical training that requires prolonged effort. Unlike repeated sprinting, which eventually causes you to have to stop and catch your breath, endurance activities allow the body to keep enough oxygen going to the muscles so the activity can be done for long periods.

Endurance training conditions muscles to become better able to obtain the nutrients and oxygen they need from the blood. Athletes who use endurance training show an improved ability to get more blood to the working muscles with each heart beat. And the muscles are able to make better use of the oxygen in the blood. The end result is improved efficiency, leading to better performance. Examples of endurance sports include long-distance running, cycling, and swimming.