Separate and simultaneous effects of aerobic exercise and anxiety on myocardial damage in the rat

The purpose of this study was to determine the effects of various programs of physical activity on anxiety-related myocardial damage in rats. The anxiety-producing stress consisted of randomly distributed applications of a disturbing but nonpainful electrical shock. Physical activity consisted of long-duration, low-speed running. Three hundred and seventy-five male albino rats were randomly assigned to five comparison groups. The results show that the anxiety treatment produced marked myocardial damage. Animals preconditioned by eight weeks of exercise prior to the introduction of the anxiety treatment did not suffer as much myocardial damage as did animals that were not preconditioned. However, a group in which exercise and anxiety were introduced simultaneously had the highest incidence of myocardial necrosis. We conclude that aerobic exercise can modify the effects of a subsequent or simultaneous anxiety-producing stressful situation on the myocardium of the laboratory rat. The time at which the exercise is imposed determined the nature of the effect.