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Table 1 Distribution characteristics of heart rate variability indices

From: Normative references of heart rate variability and salivary alpha-amylase in a healthy young male population

  Heart period
(ms)
lnHF
(ln-ms2)
lnLF
(ln-ms2)
ln(LF/HF)
(ln-ratio)
SDNN
(ms)
rMSSD
(ms)
n 417 417 417 417 417 417
mean 945.85 9.84 10.42 0.58 27.17 37.49
median 938.86 9.89 10.42 0.56 25.09 34.76
Standard deviationa 126.98 0.92 0.73 0.92 11.78 16.54
Coefficient of variation (%) 13.42 9.35 7.01 -b 43.36 44.12
Skewness 0.38 0.01 0.11 0.19 1.22 1.24
Kurtosis 0.26 0.32 -0.21 0.71 1.91 2.04
Fifth percentile 748.53 8.39 9.24 -0.90 12.4 16.98
95th percentile 1171.68 11.37 11.58 2.12 50.99 69.95
  1. HF: high frequency component; LF: low frequency component; rMSSD: root mean square of successive differences; SDNN: standard deviation of normal-to-normal intervals. Skewness is a measure of symmetry of distribution. Negative or positive skewness is indicated when the left or right tail of the histogram is longer, respectively. The skewness of a normally distributed data set is zero. Kurtosis is a measure of whether the distribution curve is peaked (positive) or flat (negative) relative to the normal distribution. The kurtosis of a normally distributed data set is zero. aStandard deviation of interindividual variation; bthe coefficient of variation of ln(LF/HF) was not calculated because it was occasionally negative.