title: Post-exercise heart rate variability recovery: a time-frequency analysis.
abstract: OBJECTIVE
  Most studies investigating the effects 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 effects 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 ((Low)PT, n = 13) or high physical training (H(igh)PT, 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 H(igh)PT compared to the (Low)PT group (P < 0.05) was observed.
  
  
  CONCLUSIONS
  These results indicate that exercise training exerts beneficial effects on post-exercise cardiac autonomic control.
authors.affiliation: Laboratory of Motor Assessment, Faculty of Physical Education and Sports, Federal University of Juiz de Fora, Brazil. tiagopecanha@usp.br
authors.forename: Tiago
authors.initials: T
authors.lastname: Peçanha
authors.affiliation: Laboratory of Motor Assessment, Faculty of Physical Education and Sports, Federal University of Juiz de Fora, Brazil.
authors.forename: Marcelle
authors.initials: M
authors.lastname: de Paula-Ribeiro
authors.affiliation: Biomedical Engineering Program (COPPE), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Olivassé
authors.initials: O
authors.lastname: Nasario-Junior
authors.affiliation: Laboratory of Motor Assessment, Faculty of Physical Education and Sports, Federal University of Juiz de Fora, Brazil.
authors.forename: Jorge Roberto Perrout
authors.initials: JR
authors.lastname: de Lima
mesh_terms: D001341:Autonomic Nervous System / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005583:Fourier Analysis; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D020127:Recovery of Function; D012016:Reference Values; D055815:Young Adult