In terms of exercise in general, excessive reliance upon the act of exercising is termed exercise dependence. According to Hamer and Karageorghis (3), it is characterized by an obsessive and unhealthy preoccupation with exercise. Research has focused largely on the behavioral aspect of it but little research has been done on the biological process that takes place.
The Affect Regulation Model states that running serves as a positive feeling enhancer and a negative feeling enhancer. It focuses on two types of runners, one who runs to reduce their distress and one that runs to increase the positive feeling (3).
The research also shows the abstinence of running increases the negative feeling, which can only be alleviated with exercise - thereby reinforcing the need to exercise more.
Exercise Dependence can also disrupt social relationships that indirectly affect psychological health.
Based on the DSM IV categorisation, exercise dependence was found to have the same characteristics as drug dependence. These include tolerance, withdrawal symptoms from complete cessation of an exercise routine, and lack of control - an intense need or want to exercise beyond what is considered normal and routine (1).
One study (2) looked at mountaineers who perform uphill and long distance walking (both of which demand a high level of aerobic performance). Outside the parameters of what is considered 'normal' for those activities, factors such as age and pre-existing conditions significantly affected the performance outcome.
This 'exercise dependence' can apply to any aerobic exercise that is performed above what is considered normal for that activity; whether it be mountaineering or running (2).