Persons with MR without DS exhibit similar age-related changes in VO2peak and peak HR as individuals without disabilities. Similar age-related changes were also observed for peak HR in individuals with DS, despite overall lower levels. However, relative VO2peak did not decline with age in persons with DS, suggesting that aerobic capacity exhibits a different age-related response in individuals with DS.

Women demonstrate greater RR interval variability than men of similar age. Enhanced parasympathetic input into cardiac regulation appears to be not only greater in women, but also protective during periods of cardiac stress. Even though women may have a more favorable autonomic profile after exercise, little research has been conducted on this issue. This study was designed to examine the cardiac autonomic response, in both male and female participants, during the early recovery from supramaximal exercise. Twenty-five individuals, aged 20 to 33 years (13 males and 12 females), performed a 30-s Wingate test. Beat-to-beat RR series were recorded before and 5 min after exercise, with the participants in the supine position and under paced breathing. Linear (spectral analysis) and nonlinear analyses (detrended fluctuation analysis (DFA)) were performed on the same RR series. At rest, women presented lower raw low frequency (LF) power and higher normalized high frequency (HF) power. Under these conditions, the LF/HF ratio of women was also lower than that of men (p < 0.05), but there were no differences in the short-term scaling exponent (a1). Even though both sexes showed a significant modification in linear and nonlinear measures of heart rate variability (HRV) (p < 0.05), women had a greater change in LF/HF ratio and a1 than men from rest to recovery. This study demonstrates that the cardiac autonomic function of women is more affected by supramaximal exercise than that of men. Additionally, DFA did not provide additional information about sexual dimorphisms, compared with conventional spectral HRV techniques.Résumé : Comparativement aux hommes du même âge, les femmes présentent une plus grande variabilité de l'intervalle RR. Une meilleure stimulation parasympathique en matière de régulation cardiaque n'est pas seulement plus importante chez les femmes, mais leur confère aussi une protection en périodes de stress cardiaque. Même si les femmes semblent disposer d'un meilleur profil autonome du coeur après la fin d'un exercice, il y a très peu d'études sur ce sujet. Cette étude analyse la réponse autonome du coeur des participants masculins et féminins au cours de la première phase de récupération d'un exercice physique d'intensité supramaximale. Vingt-cinq individus âgés de 20 à 33 ans (12 femmes, 13 hommes) participent au test de Wingate d'une durée de 30 s. Des enregistrements ECG permettent d'obtenir un ensemble de pointes RR avant le début du test et 5 min après la fin du test, au repos couché et dans une condition de contrôle respiratoire. On fait des analyses linéaires (analyse spectrale) et des analyses non linéaires (analyse des fluctuations redressées ou DFA) sur les mêmes ensembles de pointe RR. Au repos, les femmes présentent une puissance plus faible des basses fréquences (LF) brutes, mais une plus grande puissance des hautes fréquences (HF) normalisées. Dans ces conditions, le ratio LF/HF des femmes est aussi plus faible que celui des hommes (p < 0,05), mais l'exposant d'échelle (a 1 ) à court terme n'e...