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Purpose 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. Methods 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. Results Men attained greater peak values for VO 2 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). Conclusions 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.

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

This thesis intended to explore both the acute and chronic physiological adaptations of persons with Down syndrome (DS) in response to exercise. Specifically, in terms of acute exercise responses, we aimed at investigating the submaximal exercise capacity and cardiac autonomic function of adults with and without DS. Subsequently, we determined whether 12 weeks of exercise training were effective in improving exercise capacity (economy and peak oxygen uptake – VO2peak) and autonomic function both in adults with and without DS. Overall, we found that the submaximal exercise capacity of adults with DS was characterized by poor walking economy, but appropriate VO2 kinetics. As importantly, these individuals demonstrated reduced cardiac responsiveness to changes in the sympathovagal balance resulting from submaximal dynamic exercise. Findings also indicated a breakdown in their fractal scaling properties of heart rate dynamics that was transversal to resting, exercise and post-exercise recovery conditions. Moreover, compared to nondisabled participants, adults with DS showed reduced cardiodeceleration during recovery from peak exercise intensities. Finally, in general terms, a combined exercise regimen resulted in gains of similar magnitude between participants with and without DS for submaximal exercise capacity and cardiac autonomic function. In conclusion, this thesis provides evidence that persons with DS have reduced submaximal exercise capacity and that this is paired by disturbed autonomic function. Nevertheless, these results also indicate that exercise training is an effective intervention for improving their physiological function in similar magnitude as in adults without DS.