A state of chronic decrement in performance and ability to train, in which restoration may take several weeks, months, or even years.
Overtraining syndrome is not well understood, but occurs in times of excess training with inadequate recovery and often includes non-training stressors. Overtraining can produce a variety of symptoms, which include poor athletic performance, depressed immune function, altered mood states, weight loss, muscle pain, and overuse injuries. The most effective treatment for overtraining is rest. Recovery may take several weeks or even months depending on the severity of the condition. A less severe form of overtraining has been termed overreaching, which usually requires less time for recovery.