Table 2

Mean values, coefficients of variations, and correlation coefficients of ln transformed heart rate variation indices in 70 kibbutz members recorded two months apart

			Sample mean (n = 70)		Coefficient of variation (%) (n = 70)		Correlation coefficient (n = 70)	Correlation
			Sample mean (n = 70)		Coefficient of variation (%) (n = 70)		Correlation coefficient (n = 70)	Men (n = 32)	Women (n = 38)	p	Age < 50 (n = 45)	Age ⩾ 50 (n = 25)	p
SD	Free	3.63	6.0	0.77	0.71	0.83	NS	0.79	0.74	NS
SD	Metronome	3.59	6.1	0.78	0.66	0.84	NS	0.75	0.78	NS
RMSSD	Free	3.29	8.0	0.75	0.66	0.79	NS	0.83	0.62	NS
RMSSD	Metronome	3.29	7.4	0.78	0.59	0.86	< 0.05	0.81	0.73	NS
Area very low	Free	5.45	9.0	0.65	0.56	0.73	NS	0.70	0.60	NS
Area very low	Metronome	5.27	9.7	0.64	0.61	0.68	NS	0.63	0.66	NS
Area low	Free	5.30	11.5	0.68	0.69	0.70	NS	0.62	0.70	NS
Area low	Metronome	4.95	10.7	0.75	0.77	0.72	NS	0.66	0.79	NS
Area high	Free	4.95	12.1	0.76	0.74	0.78	NS	0.80	0.69	NS
Area high	Metronome	5.11	10.5	0.82	0.72	0.87	NS	0.84	0.80	NS
Total PS	Free	6.45	7.0	0.77	0.71	0.83	NS	0.78	0.74	NS
Total PS	Metronome	6.33	6.7	0.80	0.72	0.84	NS	0.77	0.82	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).
The values for the SD and RMSSD are in ms and the values for the areas and total power are in ms².
Correlation coefficient measured as between subject variability expressed as percentage of total variability.
69 cases were included for metronomic breathing.