Does the Dose of Acute Exercise Mediate Psychophysiological Responses to Mental Stress?

This investigation examined the role that different doses of acute aerobic exercise (AE) have on psychophysiological responses to mental stress. Eighty women participated in one of four experimental conditions: (a) attention control, (b) 10 min of exercise, (c) 25 min of exercise, or (d) 40 min of exercise. All exercise sessions were performed at 70% of each subject's heart rate reserve. Following each condition, subjects rested for 20 min and then completed a modified Stroop test. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were monitored at rest and during the stressor. Positive and negative affect were assessed upon entry to the laboratory, postexercise (after the 20-min rest), prior to the stressor, and after a 5-min recovery period. A priori comparisons of the 40-min exercise condition versus the attention control manipulation revealed that a demanding bout of acute AE lowered DBP and MAP reactivity to the Stroop; however, there were no significant linear trends between the dose of exercise and the extent of blood pressure (BP) reactivity. Analysis of the positive and negative affect data revealed no differences between any of the four treatment groups either prior to performing the Stroop task or following a 5-min period of recovery.