Differential effects of exercise training intensity on blood pressure and cardiovascular responses to stress in borderline hypertensive humans

Background. Psychologic stress has been associated with the development of hypertension. Aerobic exercise training appears to decrease cardiovascular responses to psychologic stress. Objective. To determine the efficacy of low-intensity and moderate-intensity exercise training in reducing blood pressure and cardiovascular responses to stress. Design. We sought to compare the cardiovascular responses to a psychologic stressor, the Stroop Color Word Task (Stroop), before and after 12 weeks of low-intensity (about 45% maximal oxygen uptake) and moderate-intensity (about 75% maximal oxygen uptake) aerobic exercise training. Methods. Eighteen borderline hypertensive subjects (resting blood pressure 139 ± 9/92 ± 9 mmHg) were divided randomly into three groups: control (no exercise), low-intensity exercise (40-50% maximal oxygen uptake), and moderate-intensity exercise (70-80% maximal oxygen uptake). Training groups exercised three times per week at the prescribed exercise intensity. Heart rate and blood pressure were recorded during the Stroop before, and after 4 and 8 weeks of exercise training. Results. In the low-intensity exercise group, exercise training attenuated mean blood pressure, systolic blood pressure, and diastolic blood pressure responses to the Stroop and decreased resting blood pressure. The moderate-intensity exercise group demonstrated a reduced diastolic blood pressure response to the Stroop. Conclusions. These results suggest that, in borderline hypertensive humans, 12 weeks of aerobic exercise training attenuates the cardiovascular responses to the Stroop. Furthermore, low-intensity exercise training appears to be a more effective stimulus than moderate-intensity exercise training in reducing resting blood pressure and blood pressure responses to stress.