Exercise addiction is a state characterized by a compulsive engagement in any form of physical exercise, despite negative consequences. While regular exercise is generally a healthy activity, exercise addiction generally involves performing excessive amounts of exercise to the detriment of physical health, spending too much time exercising to the detriment of personal and professional life, and exercising regardless of physical injury. It may also involve a state of dependence upon regular exercise which involves the occurrence of severe withdrawal symptoms when the individual is unable to exercise. Differentiating between addictive and healthy exercise behaviors is difficult but there are key factors in determining which category a person may fall into. Exercise addiction shows a high comorbidity with eating disorders.

Exercise addiction is not listed as a disorder in the DSM-5. This type of addiction can be classified under a behavioral addiction in which a person's behavior becomes obsessive, compulsive, and/or causes dysfunction in a person's life.

A concrete classification of exercise addiction has proven to be difficult due to the lack of a specific and widely accepted diagnostic model. Most interpretations of addiction have traditionally been limited to drugs and alcohol, which makes it even more difficult to identify addictive tendencies in exercise. While excessive exercise is the overarching theme with exercise addiction, the term also includes a variety of symptoms like withdrawal, "exercise buzz", and impaired physical function. Excessive exercise has been classified in different ways; sometimes as an addiction and sometimes as a more general compulsive behavior. Psychiatric case studies have shown that exaggerated exercise could lead to negligence of work and family life. With an addiction, individuals become "hooked" to the feeling of euphoria and pleasure that exercise provides. This pleasure keeps the individual from stopping and leads to excessive exercise. With a compulsion people often do not necessarily enjoy repeating certain tasks, as they may feel like performing it will fulfill a duty that is required of them. There are many opinions on whether concrete diagnostic criteria should be created for this type of addiction. Some say preoccupation with exercise that causes significant impairment in a person's life, not due to another disorder, may be enough criteria to label this disorder. Others say there is not enough information about exercise addiction to develop diagnostic criteria. As of 2007^[update], the term "excessive exercise" continues to be used while the "exercise addiction" model continues to be debated.

Three main types of disorders are associated with excessive exercise:

Five indicators of exercise addiction are:

Key differences between healthy and addictive levels of exercise include the presence of withdrawal symptoms when exercise is stopped as well as the addictive properties exercise may have leading to a dependence on exercise.

Those who succumb to exercise addiction may experience overtraining, which is best defined as a “condition of poor adaptation to a chronic period of excessive stress caused by a physical exertion, resulting in the development of the syndrome, compromising the health and sports performance”.

Overtraining includes one or more of the following:^{[unreliable source]}