title: Reproducibility and gender-related differences of heart rate variability during all-day activity in young men and women.
abstract: BACKGROUND
  Only few data are available on reproducibility over time in healthy young men and women and the corresponding gender-related changes of heart rate variability (HRV) measurements.
  
  
  METHODS
  We studied temporal and spectral HRV indices obtained from 24-hour Holter recordings in 32 healthy volunteers (14 men and 18 women, mean age 29 +/- 3 years) during 2 days of their usual all-day activity.
  
  
  RESULTS
  Time-domain measures and the spectral low-frequency (LF) and high-frequency (HF) components as well as the LF/HF ratio were comparable on both test days. Significantly higher values on test day 2 were observed only for the spectral very-low-frequency (VLF) component and for the resulting total power. Compared to men, women had higher day- and nighttime vagus-associated HRV indices, including root mean square of successive differences (RMSSD), pNN50 (NN50 count divided by the total number of all NN intervals), and HF power, and lower day- and nighttime VLF and LF power with lower LF/HF ratio and total power.
  
  
  CONCLUSIONS
  Temporal indices and the LF and HF spectral HRV measures are reproducible over usual all-day activity in young healthy subjects. Young women have higher day-and nighttime vagal tone than men with similar age range.
authors: Cardiology Service and General Internal Medical Service, University Hospital, Geneva, Switzerland. juan.sztajzel@hcuge.ch
authors: Juan
authors: J
authors: Sztajzel
authors: Michel
authors: M
authors: Jung
authors: Antonio
authors: A
authors: Bayes de Luna
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D017677:Age Distribution; D000704:Analysis of Variance; D015331:Cohort Studies; D015716:Electrocardiography, Ambulatory / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D009043:Motor Activity; D011336:Probability; D012016:Reference Values; D015203:Reproducibility of Results; D017678:Sex Distribution