title: Interval training in elderly men increases both heart rate variability and baroreflex activity.
abstract: OBJECTIVE
  Autonomic nervous system activity decreases continuously with age and appears to be a powerful predictor of disease and death. Attempts are thus made to reactivate autonomic drive with the intent of improving health.
  
  
  METHODS
  We assessed maximal oxygen consumption (VO2max), autonomic nervous system activity by heart rate variability (HRV) analysis and spontaneous cardiac baroreflex activity (SBR) in eleven elderly men (73.5+/-4.2 years) before and after a 14-week program of intensive cycloergometer interval training. The standard HRV indices were calculated using time domain (mean RR, PNN50, RMSSD, SDNN, SDANN and SDNNIDX), and Fourier transform (total power, ULF,VLF, LF, LFnu, HF, HFnu and LF/HF) analyses of 24-hour, daytime and nighttime Holter recordings. The SBR was calculated from 15-minute recordings of spontaneous blood pressure and RR interval variations using the sequence (slope, slSBR) and cross-spectral (alphaSBRHF and alphaSBRLF) methods.
  
  
  RESULTS
  After the training period,VO2max increased by 18.6 % (26.8+/-4.4 to 31.8+/-5.2 ml.kg(-1).min(-1), p<0.01). The nocturnal parasympathetic indices of HRV increased (PNN50: 3.05+/-2.21 to 5.00+/-2.87%, RMSSD: 29.1+/-7.6 to 38.8+/-10.9 ms, HF: 117+/-54 to 194+/-116 ms2/Hz, all p<0.05) as did the SBR indices (slSBR: 7.0+/-1.8 to 9.8+/-2.1 ms.mmHg(-1), p<0.01; alphaSBRHF: 6.9+/-2.2 to 10.5+/-3.7 ms.mmHg(-1), p<0.05; alphaSBRLF: 5.3+/-2.3 to 6.9+/-3.1 ms.mmHg(-1), p=0.22).
  
  
  CONCLUSIONS
  Intensive endurance training in elderly men enhanced parasympathetic parameters of HRV and, interestingly, of SBR. Physiological mechanisms and long-term clinical effects on health status should be further investigated.
authors.affiliation: Laboratoire de Physiologie, GIP E2S, Université de Saint-Etienne, Saint-Etienne, France. vincent.pichot@unit-st-etienne.fr
authors.forename: Vincent
authors.initials: V
authors.lastname: Pichot
authors.forename: Frédéric
authors.initials: F
authors.lastname: Roche
authors.forename: Christian
authors.initials: C
authors.lastname: Denis
authors.forename: Martin
authors.initials: M
authors.lastname: Garet
authors.forename: David
authors.initials: D
authors.lastname: Duverney
authors.forename: Frédéric
authors.initials: F
authors.lastname: Costes
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Barthélémy
mesh_terms: D000368:Aged / Q000502:physiology*; D015308:Anaerobic Threshold / Q000502:physiology; D017704:Baroreflex / Q000502:physiology*; D015716:Electrocardiography, Ambulatory; D005080:Exercise Test; D005583:Fourier Analysis; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010275:Parasympathetic Nervous System / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*