Preliminary evidence that exercise dependence is associated with blunted cardiac and cortisol reactions to acute psychological stress.

Low or blunted cardiovascular and cortisol reactions to acute psychological stress have been shown to characterise those with a tobacco or alcohol dependency. The present study tested the hypothesis that exercise dependency would be similarly associated with blunted reactivity. Young female exercisers (N=219) were screened by questionnaire for exercise dependence. Ten women with probable exercise dependence and 10 non dependent controls were selected for laboratory stress testing. Cardiovascular activity and salivary cortisol were measured at rest and in response to a 10-min mental arithmetic stress task. The exercise dependent women showed blunted cardiac reactions to the stress task and blunted cortisol at 10, 20, and 30 minute post stress exposure. These effects could not be accounted for in terms of group differences in stress task performance, nor could the cardiac effects be attributed to group differences in cardio-respiratory fitness. It would seem that low stress reactivity is characteristic of a wide range of dependencies, and is not confined to substance dependence. Our results offer further support for the hypothesis that blunted stress reactivity may be a peripheral marker of a central motivational dysregulation.