Overtraining results in a state of chronic physical and psychological fatigue that leads to a decline in performance and greater risk of injury. Overtraining can be an issue for all athletic types, but it is very common in endurance sports.
How does this happen? Doing a physical activity causes damage to the muscle tissues and joints, and depletes energy reserves. During the recuperation period, the body tries to regenerate and strengthen the muscles and joints. This process is called overcompensation and it makes the body stronger. In fact, for all sports, a rest period is essential because it improves the physical condition and restores energy. Overtraining has occurred when the body is no longer able to recover and rebuild muscle tissues after an intense workout. This can become a serious problem if the person is also suffering from a lack of sleep or unbalanced nutrition.