CARDIOVASCULAR RESPONSES TO ORTHOSTATIC STRESS AFTER ACUTE AEROBIC AND RESISTIVE EXERCISE

Abstract

976 Recent studies have reported impaired cardiovascular control after exercise. The purpose of this study was to compare the cardiovascular responses to postural stress after an acute bout of aerobic and resistive exercise. Seven subjects (6 female, and 1 male) performed a stand test after no intervention, acute aerobic exercise and acute resistive exercise. During the aerobic exercise, subjects cycled at 70% of their heart rate max for 30 minutes. The resistive exercise consisted of 2 sets of upper and lower body exercises, one at 50% and one at 70% of 1 RM. Subjects were seated in an upright position for 10 minutes and then were asked to stand for 10 minutes, while leaning against a wall for balance. While standing, cardiac output, stroke volume, systolic and diastolic blood pressure, and heart rate were measured. Heart rate was higher during standing in the aerobic condition (110 ± 1.0 bpm) when compared to either resistive exercise (91.2 ± 6.3 bpm) or control (79.8 ± 3.7 bpm). Systolic blood pressure was unchanged between conditions during standing. Cardiac output decreased during each condition, however, there were no differences between conditions. Standing stroke volume after aerobic exercise (35.0 ± 3.9) was lower than control (51.2 ± 11.8) or after resistive exercise (54.2 ± 5.4). These data suggest that an acute bout of aerobic exercise does significantly alter the cardiovascular response to an orthostatic challenge to a much greater extent than resistive exercise, possibly by altering cardiovascular control at the start of the challenge.