It is no secret among athletes that in order to improve performance you’ve got to work hard. However, hard training breaks you down and makes you weaker, It is rest that makes you stronger. Improvement only occurs during the rest period following hard training. This adaptation is accomplished by improving efficiency of the heart and certain systems within the muscle cells. During recovery periods these systems build to greater levels to compensate for the stress that you have applied. The result is that you are now at a higher level of performance.
    If sufficient rest is not included in a training program, imbalance between excess training and inadequate rest will occur, and performance will decline. The “overtraining syndrome(综合症)” is the name given to the collection of emotional, behavioral, and physical symptoms due to overtraining that has persisted for weeks to months. It is marked by cumulative exhaustion that persists even after recovery periods.
    The most common symptom is fatigue. This may limit workouts and may be present at rest. The athlete may also become moody, easily imitated, have altered sleep patterns, become depressed, or lose the competitive desire and enthusiasm for the sport, Some will report decreased appetite and weight loss. Physical symptoms include persistent muscular soreness, increased frequency of viral (病毒性的) illnesses, and increased incidence of injuries.
    The treatment for the overtraining syndrome is rest. The longer the overtraining has occurred, the more rest required, Therefore, early detection is very important, If the overtraining has only occurred for a short period of time (e.g. 3-4 weeks) then interrupting training for 3-5 days is usually sufficient rest. It is important that the factors that lead to overtraining be identified and corrected. Otherwise, the overtraining syndrome is likely to recur. The overtraining syndrome should be considered in any athlete who manifests symptoms of prolonged fatigue and whose performance has leveled off or decreased. It is important to exclude any underlying illness that may be responsible for the fatigue.