title: Heart rate variability changes during high frequency yoga breathing and breath awareness.
abstract: BACKGROUND
  Pre and post comparison after one minute of high frequency yoga breathing (HFYB) suggested that the HFYB modifies the autonomic status by increasing sympathetic modulation, but its effect during the practice was not assessed.
  
  
  METHODS
  Thirty-eight male volunteers with group average age ± S.D., 23.3 ± 4.4 years were each assessed on two separate days in two sessions, (i) HFYB and (ii) breath awareness. Each session was for 35 minutes, with 3 periods, i.e., pre (5 minutes), during HFYB or breath awareness (15 minutes) and post (5 minutes).
  
  
  RESULTS
  There was a significant decrease in NN50, pNN50 and the mean RR interval during and after HFYB and after breath awareness, compared to the respective 'pre' values (p < 0.05) (repeated measures ANOVA followed by post-hoc analysis). The LF power increased and HF power decreased during and after breath awareness and LF/HF ratio increased after breath awareness (p < 0.05).
  
  
  CONCLUSIONS
  The results suggest that there was reduced parasympathetic modulation during and after HFYB and increased sympathetic modulation with reduced parasympathetic modulation during and after breath awareness.
authors.affiliation: Patanjali Research Foundation, Patanjali Yogpeeth, Haridwar, India. pyp.research@gmail.com.
authors.forename: Shirley
authors.initials: S
authors.lastname: Telles
authors.forename: Nilkamal
authors.initials: N
authors.lastname: Singh
authors.forename: Acharya
authors.initials: A
authors.lastname: Balkrishna