Sistema FMUSP-HC: Faculdade de Medicina da Universidade de São Paulo (FMUSP) e Hospital das Clínicas da FMUSPMARIN, T.C.PEçANHA, T.PIRES, F.O.CAVINATO, C.CASTRO, V.M. deCARMO, E.C. DoBRITO, L.C. de2021-04-292021-04-292020JOURNAL OF PHYSICAL EDUCATION AND SPORT, v.20, p.2851-2858, 20202247-8051https://observatorio.fm.usp.br/handle/OPI/40221The aim of this study was to compare heart rate recovery (HRR) and its association with energy systems of contributionafter isocaloric exercise sessions conducted at low (LI) and moderate (MI) intensity. Nine subjects randomly underwent two isocaloric exercise sessions, one conducted at LI (10% < velocity from anaerobic threshold) and other at MI (10% < velocity from respiratory compensation point). Blood lactate was measured pre-and post-exercise and rate perceived effort was assessed immediately after the exercise; during the exercise was estimated the contribution of oxidative, glycolytic and ATP-PCr systems. HRR30s, HRR60s (percentage of HR reduction after 30s and 60s of recovery), T30 (short-term time constant of HRR) and rMSSD30s (square root of the mean of the sum of the squares of differences between adjacent R-R intervals of subsequent 30s segments) were measured as parasympathetic reactivation markers. HRR300s (percentage of HR reduction after 300s of recovery) and HRRt (long-term time constant of the first order exponential fitting of HRR) were measured as sympathetic withdrawal markers. Paired t-test and two-way ANOVA were employed to compare LI and MI sessions and Pearson or Spearman correlations were used to analyze the association between energy contribution and HRR indexes, P<0.05. LI and MI did not present differences in HRR indexes. Regarding energy contribution, HRR30s was positively associated with oxidative contribution and negatively associated to ATP-PCr contribution, while HRR60s was negatively associated with glycolitc contribution, and T30 was negatively associated with oxidative contribution and positively associated with ATP-PCr contribution. No associations were observed after MI.Therefore, in recreationally active men, the caloric expenditure seems to play a role on HRR indexes after low and moderate intensity of a short matched-caloric expenditure aerobic exercise session,and parasympathetic reactivation is associated with greater oxidative, but lower glycolitic and ATP-PCr energy systems of contribution. © JPES.engopenAccessEnergy systemsParasympathetic reactivationPhysical activitySympathetic withdrawalarticleCopyright EDITURA UNIVERSITATII DIN PITESTI10.7752/jpes.2020.s5387