Marathon training requires the sprinter to assemble their intensity week to week which makes them progressively susceptible to damage the more they increase their mileage. In extraordinary instances, over-exercising induces serious performance loss. Unaccustomed overexertion of muscles leads to rhabdomyolysis harm to muscle most often seen in new armed force recruits. A study shows that in the last 10– 15 years up to 90% of long distance runners have suffered physical damage from their training. Stopping excessive exercise suddenly may make a change in state of mind. Exercise should be controlled by each body's inalienable limitations.
Another danger is over training, in which the intensity or volume of training exceeds the body's ability to recoup between bouts. An increased frequency is also associated with high volume/intensity training, as well as with excessive exercise, such as in a marathon. While one set of joints and muscles may have the tolerance to withstand various marathons, another body might be harmed by 20 minutes of light running. This must be resolved for every individual. One result of impeding over training is suppressed immune function, with an increased rate of upper respiratory tract contamination. An excess of exercise may cause a woman to cease menstruation, a symptom known as amenorrhea.