Table 4

Age differences in heart rate variabilty measures (ln transformed, adjusted for sex) in supine position

SDRMSDDArea very lowArea lowArea highTotal PSRatio low:high
MeanMedianMeanMedianMeanMedianMeanMedianMeanMedianMeanMedianMeanMedian
Free breathing
35–44 years (n = 91)3.903.843.483.496.116.035.865.885.345.297.006.795.135.06
25–75 percentile(3.62–4.22)(3.14–3.80)(5.52–6.63)(5.07–6.53)(4.62–5.93)(6.47–7.67)(4.54–5.65)
45–54 years (n = 108)3.603.653.173.205.605.635.185.214.694.706.406.475.095.12
25–75 percentile(3.32–3.87)(2.80–3.45)(5.10–6.18)(4.54–6.01)(3.96–5.31)(5.83–7.03)(4.55–5.70)
55–65 years (n = 94)3.613.583.103.085.705.645.165.134.424.476.416.385.345.33
25–75 percentile(3.23–4.06)(2.69–3.46)(5.09–6.37)(4.29–6.18)(3.62–5.23)(5.66–7.30)(4.98–5.85)
p value 0.009 0.0040.003< 0.00010.009 0.0140.03
p value (controlled for HR)0.01 0.0030.0005< 0.00010.010 0.02 0.03
Metronomic breathing
35–44 years (n = 91)3.763.813.413.465.705.715.395.395.195.316.676.704.814.81
25–75 percentile(3.52–3.99)(3.11–3.71)(4.99–6.33)(4.79–6.02)(4.43–5.78)(6.19–7.07)(4.27–5.43)
45–54 years (n = 107)3.543.513.163.165.405.274.884.964.664.666.246.194.834.79
25–75 percentile(3.25–3.79)(2.87–3.47)(4.73–5.90)(4.21–5.60)(4.03–5.31)(5.70–6.83)(4.32–5.48)
55–65 years (n = 93)3.483.453.053.035.365.334.604.594.414.366.096.014.794.85
25–75 percentile(3.15–3.81)(2.70–3.40)(4.76–5.92)(3.92–5.37)(3.58–5.22)(5.54–6.78)(4.40–5.28)
p value < 0.00010.0060.0008< 0.00010.011 < 0.0001NS
p value (controlled for HR)< 0.00010.0050.0002< 0.00010.014 < 0.0001NS
  • SD, standard deviation of RR interval; RMSSD, root mean square of differences of successive RRs; area very low, the area at very low frequency (0.0033 to < 0.04 Hz); area low the area at low frequency (0.04 to < 0.15 Hz); area high, the area at high frequency (0.15 to < 0.40 Hz); total PS, total power spectrum (0.0033 to < 0.40 Hz); ratio low to high, ratio of low frequency to high frequency.

  • The values for the SD and RMSSD are in ms and the values for the areas and total power are in ms2.

  • p value is from a linear regression of heart rate variability on age.

  • p value (controlled for heart rate) is from a linear regression of HRV on age and HR.