Comparison of left ventricular performance in healthy young women and men during exercise

Abstract

Background. Previous studies show sex-related differences in left ventricular (LV) response to exercise. It is not clear, however, whether these differences are also seen in younger healthy subjects. Methods and Results. This study examined the changes in LV performance during dynamic upright exercise in 11 healthy men and 19 healthy young women according to the Bruce protocol and an individualized ramp protocol. There were no significant differences between the two protocols for either men or women in heart rate, blood pressure, LV ejection fraction (EF) (measured by ambulatory nuclear detector), and measured oxygen consumption. The peak oxygen consumption was higher in men than in women (44 ± 13 vs 36 ± 9 ml/kg/min; p < 0.05), but the peak heart rate, systolic blood pressure, and EF were similar. The change in EF (from rest to exercise) was 19% ± 8% in men and 19% ± 11% in women with the Bruce protocol (difference not significant) and 26% ± 9% in men and 19% ± 6% in women with the ramp protocol (difference not significant). At peak exercise, both men and women showed an increase in end-diastolic volume (29% ± 14% vs 23% ± 11%; difference not significant) and a decrease in end-systolic volume (41% ± 15% vs 43% ± 21%) (difference not significant). The increase in cardiac output during exercise was due to an increase in heart rate and stroke volume in both men and women. At submaximal exercise, however, the decrease in end-systolic volume was less in women than in men ( p < 0.05). Conclusions: There are no sex-related differences in compensatory mechanism during dynamic exercise in healthy subjects. The changes in contractility and LV volume are not affected by the exercise protocol.