Table 3. Descriptive statistics and results of Mann-Whitney U tests with respect to linear HRV indices according to Tests I comparing each two age clustered (25–49 years and 50–74 years) female and/or male subject groups.

		Mean ± standard deviation				Mann-Whitney U test
MA	HRV-index	YF	YM	EF	EM	YM-EM	YF-EF	YF-YM	EF-EM
	Number (N =)	571	744	211	380
TD	meanNN	901 ± 117	930 ± 133	880 ± 115	911 ± 128	NS	NS	**	*
	sdNN	44.9 ± 19.2	45.8 ± 18.8	31.6 ± 13.6	33.0 ± 14.8	****	****	NS	NS
	cvNN	0.05 ± 0.02	0.05 ± 0.02	0.04 ± 0.01	0.04 ± 0.01	****	****	NS	NS
	sdaNN1	18.1 ± 13.2	18.2 ± 11.4	14.3 ± 8.3	15.1 ± 9.7	**	**	NS	NS
	rmssd	36.5 ± 20.1	34.0 ± 18.3	22.0 ± 13.2	20.5 ± 11.0	****	****	NS	NS
	pNN50	0.17 ± 0.18	0.15 ± 0.16	0.05 ± 0.09	0.04 ± 0.07	****	****	NS	NS
	pNNl20	0.49 ± 0.21	0.52 ± 0.22	0.71 ± 0.21	0.74 ± 0.19	****	****	NS	NS
	renyi4	3.87 ± 0.54	3.88 ± 0.55	3.34 ± 0.55	3.39 ± 0.58	****	****	NS	NS
	shannon_h	4.30 ± 0.53	4.32 ± 0.53	3.79 ± 0.55	3.84 ± 0.57	****	****	NS	NS
FD	LF	159 ± 181	203 ± 262	66 ± 83	84 ± 115	****	****	**	*
	HF	125 ± 147	101 ± 143	41.4 ± 72.1	29.5 ± 36.6	****	****	*	*
	P	531 ± 638	533 ± 534	247 ± 282	284 ± 313	****	****	NS	NS
	LF/HF	2.09 ± 2.05	3.33 ± 3.47	2.75 ± 2.93	4.29 ± 4.06	**	*	****	**
	LF/P	0.31 ± 0.14	0.38 ± 0.16	0.28 ± 0.13	0.31 ± 0.15	**	NS	****	*
	HF/P	0.24 ± 0.15	0.19 ± 0.13	0.17 ± 0.12	0.12 ± 0.10	****	**	**	**
	LFn	0.58 ± 0.19	0.67 ± 0.17	0.63 ± 0.18	0.72 ± 0.17	**	*	****	**
	HFn	0.42 ± 0.19	0.33 ± 0.17	0.37 ± 0.18	0.28 ± 0.17	**	*	****	**

Abbreviations: YF, young females; YM, young males; EF, elderly females; EM, elderly males; MA, method of analysis; TD, time domain; FD, frequency domain; level of significance:

****p<10⁻²⁰,

***p<10⁻¹⁰,

**p<Bonferroni criterion = 0.0007,

*p<0.01, NS, no significance.