title: Heart rate recovery and parasympathetic modulation in boys and girls following maximal and submaximal exercise.
abstract: OBJECTIVE
  This study examined heart rate recovery (HRR) and heart rate variability (HRV) following submaximal and maximal exercise in boys (n = 13; 10.1 ± 0.8 years) and girls (n = 12; 10.1 ± 0.7 years).
  
  
  METHODS
  Participants completed 10 min of supine rest followed by a graded exercise test to maximal effort. On a separate day, participants performed submaximal exercise at ventilatory threshold. Immediately following both exercise bouts, 1-min HRR was assessed in the supine position. HRV variables were analyzed under controlled breathing in the time and frequency domains over the final 5 min of rest and recovery.
  
  
  RESULTS
  There were no significant differences in HRR following maximal and submaximal exercise between boys (58 ± 8 and 59 ± 8 beats min(-1), respectively) and girls (54 ± 6 and 52 ± 19 beats min(-1), respectively). There also were no significant interactions between groups from rest to recovery from maximal exercise for any HRV variables. However, there was a difference in the response between sexes from rest to recovery from submaximal exercise for log transformed standard deviation of NN intervals (lnSDNN) and log transformed total power (lnTP). No differences were observed for lnSDNN at rest (boys = 4.61 ± 0.28 vs. girls = 4.28 ± 0.52 ms) or during recovery (lnSDNN: boys 3.78 ± 0.46 vs. girls 3.87 ± 0.64 ms and lnTP: boys 7.33 ± 1.09 vs. girls; 7.44 ± 1.24 ms(2)). Post hoc pairwise comparisons showed a significant difference between boys and girls for lnTP at rest (boys = 9.14 ± 0.42 vs. girls = 8.30 ± 1.05 ms(2)).
  
  
  CONCLUSIONS
  Parasympathetic modulation was similar between boys and girls at rest and during recovery from exercise, which could explain similarities observed in HRR.
authors.affiliation: Human Performance Laboratory, Ball State University, Muncie, IN, 47303, USA. jpguilkey@bsu.edu.
authors.forename: J P
authors.initials: JP
authors.lastname: Guilkey
authors.affiliation: Human Performance Laboratory, Ball State University, Muncie, IN, 47303, USA.
authors.forename: M
authors.initials: M
authors.lastname: Overstreet
authors.affiliation: Human Performance Laboratory, Ball State University, Muncie, IN, 47303, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Mahon
mesh_terms: D002648:Child; D015444:Exercise; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D010275:Parasympathetic Nervous System / Q000502:physiology*; D012737:Sex Factors
keywords: Cardiovascular regulation; Heart rate variability; Pediatrics; Sex differences