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Abstract
The present study experimentally tested the cross-stressor adaptation hypothesis by examining whether endurance exercise training leads to reductions in the physiological stress response to a psychosocial stressor. We randomly assigned 149 healthy men to a 12-week exercise training, relaxation training, or a wait list control group. Before and after intervention we assessed the groups' physical fitness (lactate testing) and compared their physiological stress responses to the Trier Social Stress Test for Groups in terms of salivary free cortisol, heart rate (HR) and heart rate variability (HRV); the final sample consisted of 96 subjects. As hypothesized, the exercise training significantly improved fitness and reduced stress reactivity in all three parameters; however, it only improved stress recovery in terms of HR. The relaxation program reduced only cortisol, but not HR or HRV reactivity; no changes emerged for the control group. The findings suggest that the cross-stressor adaptation hypothesis is valid for cardiovascular as well as endocrine stress reactivity.[PUBLICATION ABSTRACT]