Aerobic exercise is frequently recommended as a stress management strategy. This study examined the influence of 30 minutes of aerobic exercise in reducing cardiovascular reactivity to a subsequent stressor compared to a nonexercise attention control condition in 16 males (<u>m</u> age = 21 yrs; moderate activity level; positive family history for hypertension) using a within subject design. The order of experimental conditions was counterbalanced across subjects. During the exercise condition, subjects pedaled for 30 minutes on a bicycle ergometer at 59% ± 7.2 of their maximum (<u>m</u> V0₂= 48.5 ml/kg/min ± 10.7). subjects completed a physical activity questionnaire and anthropometric measurements during the 30 minute attention control condition. Forty-five minutes after the exercise or attention control sessions, BP, HR, stroke volume (SV) and total peripheral resistance (TPR) were measured at baseline, during a pre-stressor anticipation period, and during the cold pressor test. stroke volume was measured with impedance cardiography and total peripheral resistance (TPR) was estimated. SBP was significantly lower during the second minute of the anticipation period (F [1,29] = 4.75, p = .04) forty-five minutes after exercising compared to the attention control condition. There were no significant differences between conditions for DBP, TPR or SV. These findings suggest that acute aerobic exercise may moderate SBP response to a subsequent non-exercise stressor. / Master of Science