THE EFFECT OF GENDER ON AEROBIC POWER AND EXERCISE HEMODYNAMICS IN HYPERTENSIVE ADULTS

To study the influence of gender on peak oxygen uptake and on the hemo dynamic response to dynamic exercise in essential hypertension, 45 mal e and 45 female patients, matched for age and blood pressure, were stu died. Blood pressure was measured intra-arterially and cardiac output by the direct oxygen Fick method. Anthropometric gender differences we re accounted for by statistical adjustment for height and weight. The increase of absolute and adjusted stroke volume from sitting at rest t o submaximal (50 W) and to peak bicycle exercise was smaller in women than in men (P < 0.05). At 50 W, oxygen uptake (0.96 vs 0.97 l.min(-1) ) and cardiac output (10.9 vs 11.2 l.min(-1)) were not different betwe en women and men, due to the steeper exercise-induced rises of heart r ate (P < 0.001) and arteriovenous oxygen difference (P < 0.05) in the women. Women reached the same peak heart rate as men (168 vs 173 b.min (-1)), so that the lower (P < 0.001) stroke volume (77 vs 99 ml) and c ardiac output (12.9 vs 17.0 l.min(-1)), together with the lower hemogl obin concentration, contributed to their impaired peak oxygen uptake ( P < 0.001), both before (1.35 vs 2.17 l.min(-1)) and after adjustment for body size (1.44 vs 2.07 l.min(-1)). In conclusion, at fixed submax imal exercise, women achieve the same oxygen uptake and cardiac output as men despite a lower stroke volume, through adaptations of heart ra te and peripheral oxygen extraction; their peak aerobic power and card iac output are, however, substantially lower than in men.