Types of Overtraining
The overtraining symptoms that an athlete develops are specific to the type of training. When anaerobic training is involved, athletes often develop sympathetic overtraining characteristics. This occurs primarily in young athletes in sports where strength, speed and coordination are important and where large quantities of intense anaerobic exercises~ are performed, which can contribute to the development of a sympathetic overtraining syndrome. The sympathetic over training syndrome shows an increased sympathetic activity in the resting state, which contributes to the following symptoms: increased resting heart rate, decreased lean body mass, decreased appetite, disturbed sleep, decreased performance, decreased recovery after exercise, increased irritability and emotional lability, loss of training and competitive desire, increased resting blood pressure increased incidences of injuries and infections, and decreased maximal plasma lactate levels during exercise.
When large amounts of aerobic training are performed, the athlete seems to develop in a manner opposite to the sympathetic over training syndrome: the parasympathetic over training syndrome. This appears to occur more often among older athletes in sports like swimming, cycling and running. This syndrome is more difficult to identify because the symptoms are less alarming and are somewhat similar' to the effects of training improvement. This means that it is often diagnosed after a considerable delay, which makes it more difficult for the athlete to fully recover.
The parasympathetic over training syndrome in the resting state contributes to the following symptoms: low resting heart rate, early fatigue, decreased performance, quick recovery of heart rate after exercise, more sleep than usual, diminished counter-regulatory capacity against hypoglycemia, and depression. Parasympathetic over training may be an advanced state of overtraining closely associated with exhaustion of the neuroendocrine system, while the sympathetic type may simply reflect a stress response that eventually leads to exhaustion. It should be noted that sympathetic and parasympathetic over training are not well documented.
Overtraining may occur when combined stresses from training, environment, job and personal life exceed an individual's capacity to adapt. Overtraining may also result from sudden increases in training loads and inappropriate training, compromising recovery and super compensation. Many athletes attempt to train too much, too soon. They have the desire to do more, exceeding their ability to adapt. The body has a protective physiological response to decrease performance, or "shutdown" when the capacity to adapt is exceeded.
It appears that the susceptibility to over training varies between individuals. Highly motivated athletes seem to be at higher risk than other athletes. Some experts claim that women may be at greater risk than men of overtraining because of their tendency to push themselves harder in training, although this is not accepted by others. The intensity of training seems to contribute more than training duration to overtraining (19), especially when there is too much intense anaerobic work for too long a period of time, with many competitive events and little recovery in between. It also appears that the quantity of training and the duration of training are more potent contributors to overtraining than the specific type of training performed. Additionally, the overall health status of an athlete may influence the risk of over training. It has been indicated that infectious diseases also affect muscular function, and it is conceivable that the associated decreases in exercise tolerance may result from over training when training is resumed too quickly.