Sexual dimorphism in heart rate recovery from peak exercise

There is lack of consensus on whether sex, per se, affects heart rate recovery (HRR). To discriminate between the role of sex and that of cardiovascular fitness on HRR, we compared two groups of male and female participants matched for age and peak oxygen uptake (VO_2peak) percentile.

Forty healthy individuals with above-average cardiovascular fitness (VO_2peak >50th percentile), aged 18-27 years (23 men; 17 women), performed maximal cycle-ergometer tests with cardiorespiratory measurements. HRR was obtained at 1 and 2 min of passive recovery. Multiple linear regression analysis was used to determine whether the relationship between VO_2peak and HRR differed between sexes.

Men attained greater peak values for VO₂ and work rate (p < 0.05). Both groups of participants exhibited similar heart rate response to peak exercise and no sex differences were observed in VO_2peak percentile or ventilatory threshold. HRR at 1 and 2 min of passive recovery was similar between sexes. In multiple linear models, VO_2peak explained 11.2% of the variance in HRR_1min both in men and women (p < 0.05). Most importantly, sex, VO_2peak, and their interaction were all significant predictors of HRR_2min (explained variance 29.2%) (p < 0.05).

This study shows that, for a given VO_2peak percentile (>50th percentile), there is no sexual dimorphism in HRR obtained at 1 or 2 min of recovery. It also demonstrates that, in persons with similar VO_2peak values, HRR obtained at 2 min of peak exercise cessation is affected by sex.