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Post-exercise heart rate variability recovery: a time-frequency analysis

Objective Most studies investigating the eff ects of non-pharmacological interventions, such as physical training (PT), on cardiac autonomic control, assessed the HRV only in resting conditions. Recently, a new time-frequency mathematical approach based on the short-time Fourier transform (STFT) method has been validated for the assessment of HRV in non-stationary conditions such as the immediate post-exercise period. The aim of this study was to evaluate the eff ects of the PT on post-exercise cardiac autonomic control using the time-frequency STFT analysis of the HRV. Methods Twenty-one healthy male volunteers participated in this study. The subjects were initially evaluated for their physical exercise/sport practice and allocated to groups of low physical training (LowPT, n = 13) or high physical training (HighPT, n = 8). The post-exercise HRV was assessed by the STFT method, which provides the analysis of dynamic changes in the power of the low- and high-frequency spectral components (LF and HF, respectively) of the HRV during the whole recovery period. Results Greater LF (from the min 5 to 10) and HF (from the min 6 to 10) in the post-exercise period in the HighPT compared to the LowPT group (P < 0.05) was observed. Conclusion These results indicate that exercise training exerts benefi cial eff ects on post-exercise cardiac autonomic control.