SD | RMSDD | Area very low | Area low | Area high | Total PS | Ratio low:high | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|

Mean | Median | Mean | Median | Mean | Median | Mean | Median | Mean | Median | Mean | Median | Mean | Median | |||||||

Free breathing
| ||||||||||||||||||||

35–44 years (n = 91) | 3.90 | 3.84 | 3.48 | 3.49 | 6.11 | 6.03 | 5.86 | 5.88 | 5.34 | 5.29 | 7.00 | 6.79 | 5.13 | 5.06 | ||||||

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) | 3.60 | 3.65 | 3.17 | 3.20 | 5.60 | 5.63 | 5.18 | 5.21 | 4.69 | 4.70 | 6.40 | 6.47 | 5.09 | 5.12 | ||||||

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) | 3.61 | 3.58 | 3.10 | 3.08 | 5.70 | 5.64 | 5.16 | 5.13 | 4.42 | 4.47 | 6.41 | 6.38 | 5.34 | 5.33 | ||||||

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 | 0.004 | 0.003 | < 0.0001 | 0.009 | 0.014 | 0.03 | |||||||||||||

p value (controlled for HR) | 0.01 | 0.003 | 0.0005 | < 0.0001 | 0.010 | 0.02 | 0.03 | |||||||||||||

Metronomic breathing
| ||||||||||||||||||||

35–44 years (n = 91) | 3.76 | 3.81 | 3.41 | 3.46 | 5.70 | 5.71 | 5.39 | 5.39 | 5.19 | 5.31 | 6.67 | 6.70 | 4.81 | 4.81 | ||||||

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) | 3.54 | 3.51 | 3.16 | 3.16 | 5.40 | 5.27 | 4.88 | 4.96 | 4.66 | 4.66 | 6.24 | 6.19 | 4.83 | 4.79 | ||||||

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) | 3.48 | 3.45 | 3.05 | 3.03 | 5.36 | 5.33 | 4.60 | 4.59 | 4.41 | 4.36 | 6.09 | 6.01 | 4.79 | 4.85 | ||||||

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 | < 0.0001 | 0.006 | 0.0008 | < 0.0001 | 0.011 | < 0.0001 | NS | |||||||||||||

p value (controlled for HR) | < 0.0001 | 0.005 | 0.0002 | < 0.0001 | 0.014 | < 0.0001 | NS |

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 ms

^{2}.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.