Cardiovascular and autonomic responses after exercise sessions with different intensities and durations

BACKGROUND Several studies have reported the phenomenon of post-exercise hypotension. However, the factors that cause this drop in blood pressure after a single exercise session are still unknown. OBJECTIVE To investigate the effects of aerobic exercise on the acute blood pressure response and to investigate the indicators of autonomic activity after exercise. METHODS Ten male subjects (aged 25 ± 1 years) underwent four experimental exercise sessions and a control session on a cycle ergometer. The blood pressure and heart rate variability of each subject were measured at rest and at 60 min after the end of the sessions. RESULTS Post-exercise hypotension was not observed in any experimental sessions (P > 0.05). The index of parasympathetic neural activity, the RMSSD, only remained lower than that during the pre-exercise session after the high-intensity session (Δ = -19 ± 3.7 for 15-20 min post-exercise). In addition, this value varied significantly (P < 0.05) between the high- and low-intensity sessions (Δ = -30.7 ± 4.0 for the high intensity session, and Δ = -9.9 ± 2.5 for the low intensity session). CONCLUSION The present study did not find a reduction in blood pressure after exercise in normotensive, physically active young adults. However, the measurements of the indicators of autonomic neural activity revealed that in exercise of greater intensity the parasympathetic recovery tends to be slower and that sympathetic withdrawal can apparently compensate for this delay in recovery.