Attenuation of stress-induced hypertension by exercise independent of training effects: an animal model.

The present study attempted to determine if exercise, in the absence of physical training, could alter development of hypertension during chronic exposure to a psychosocial stressor. Two groups of genetically normotensive rats were exposed to social stress for 7 days, following 5 weeks of acclimation to social isolation. One group had access to exercise in a running wheel during the stress period, while the second group did not. Blood pressure, heart rate, body weight, and running activity were monitored throughout the study, and heart and adrenal gland weights were obtained following sacrifice of the animals after exposure to stress. Blood pressure increased significantly to hypertensive levels on days 4 and 7 in the group denied access to exercise but was unchanged in the exercise group. Degree of attenuation of stress-induced hypertension was unrelated to amount of running activity. There were no differences in body weight, heart rate, or organ weight between groups. Exercise appeared to act specifically via diversional, or coping, mechanisms to buffer the response of the body to stress.