. 2015 Mar 30;10(3):e0118308. doi: 10.1371/journal.pone.0118308

Table 8. Descriptive statistics and results of Kruskal-Wallis test followed by Mann-Whitney U tests with respect to nonlinear HRV indices comparing each two age decades in males (Tests II, comparison of five different age decades: 1 = 25–34, 2 = 35–44, 3 = 45–54, 4 = 55–64 and 5 = 65–74 years).

		1 (N = 330)	2 (N = 292)	3 (N = 235)	4 (N = 183)	5 (N = 84)	1–5	1 vs. 2	2 vs. 3	3 vs. 4	4 vs. 5
MA	HRV-index	Mean ± standard deviation					KW test	Mann-Whitney U tests
SD	shannon_SD	3.15 ± 0.42	2.95 ± 0.44	2.62 ± 0.47	2.42 ± 0.49	2.29 ± 0.47	^****	^**	^****	^**	NS
	forbword	25.5 ± 9.5	30.1 ± 9.3	36.2 ± 8.5	38.9 ± 8.6	39.8 ± 9.1	^****	^**	^****	^*	NS
	wpsum02	0.45 ± 0.22	0.53 ± 0.22	0.67 ± 0.20	0.73 ± 0.20	0.79 ± 0.18	^****	^**	^**	^*	NS
	wpsum13	0.10 ± 0.09	0.10 ± 0.09	0.08 ± 0.08	0.07 ± 0.08	0.05 ± 0.07	^***	NS	^*	^*	NS
	wsdvar	1.32 ± 0.42	1.23 ± 0.43	1.02 ± 0.46	0.88 ± 0.48	0.75 ± 0.43	^****	^*	^**	^*	^*
	phvar5	0.48 ± 0.19	0.39 ± 0.19	0.28 ± 0.17	0.22 ± 0.16	0.19 ± 0.16	^****	^**	^**	^*	NS
	plvar20	0.07 ± 0.16	0.12 ± 0.22	0.25 ± 0.28	0.36 ± 0.32	0.43 ± 0.31	^****	^**	^****	^**	NS
	fwrenyi025	3.49 ± 0.31	3.33 ± 0.33	3.09 ± 0.37	2.95 ± 0.40	2.89 ± 0.39	^****	^**	^****	^*	NS
	fwrenyi4	2.55 ± 0.54	2.31 ± 0.54	1.93 ± 0.51	1.72 ± 0.48	1.59 ± 0.46	^****	^**	^****	^**	NS
DFA	α1	0.93 ± 0.20	0.99 ± 0.23	1.10 ± 0.22	1.15 ± 0.22	1.13 ± 0.26	^****	^**	^**	NS	NS
DFA	α2	0.85 ± 0.23	0.87 ± 0.21	0.96 ± 0.21	0.96 ± 0.19	1.01 ± 0.21	^***	NS	^**	NS	NS
CE	H_c ^3,3	0.80 ± 0.08	0.77 ± 0.08	0.71 ± 0.09	0.67 ± 0.09	0.65 ± 0.08	^****	^**	^****	^*	NS
STSD	ST_MP	0.70 ± 0.07	0.72 ± 0.07	0.75 ± 0.06	0.76 ± 0.07	0.75 ± 0.08	^***	^**	^**	NS	NS
	ST_0V	0.06 ± 0.08	0.04 ± 0.06	0.03 ± 0.06	0.02 ± 0.05	0.03 ± 0.07	^***	^**	^*	NS	NS
	ST_1V	0.49 ± 0.12	0.52 ± 0.13	0.55 ± 0.14	0.57 ± 0.14	0.55 ± 0.17	^**	^*	NS	NS	NS
	ST_2V	0.26 ± 0.10	0.25 ± 0.10	0.20 ± 0.10	0.19 ± 0.11	0.19 ± 0.12	^***	NS	^**	NS	NS
	ST_INC	0.09 ± 0.05	0.10 ± 0.05	0.07 ± 0.04	0.07 ± 0.05	0.06 ± 0.04	^***	NS	^**	NS	NS
	ST_DESC	0.08 ± 0.04	0.08 ± 0.05	0.07 ± 0.04	0.06 ± 0.04	0.06 ± 0.05	^**	NS	^**	NS	NS
	ST_PEAK	0.14 ± 0.04	0.13 ± 0.05	0.14 ± 0.06	0.14 ± 0.06	0.15 ± 0.06	NS	NS	NS	NS	NS
	ST_VAL	0.14 ± 0.05	0.13 ± 0.05	0.14 ± 0.06	0.14 ± 0.05	0.16 ± 0.06	^**	^*	NS	NS	NS
	ST_2LV	0.17 ± 0.07	0.18 ± 0.08	0.14 ± 0.07	0.13 ± 0.08	0.12 ± 0.08	^***	NS	^**	NS	NS
	ST_2UV	0.28 ± 0.08	0.26 ± 0.09	0.28 ± 0.09	0.29 ± 0.09	0.31 ± 0.11	^*	^*	NS	NS	NS
PPA	SD1	28.1 ± 14.1	22.7 ± 11.7	16.3 ± 7.7	14.0 ± 7.8	13.4 ± 7.6	^****	^**	^**	^*	NS
	SD2	64.4 ± 27.0	58.3 ± 21.7	49.1 ± 20.0	43.8 ± 19.8	39.1 ± 18.1	^****	^*	^**	^*	NS
	SD1/SD2	0.44 ± 0.12	0.39 ± 0.13	0.34 ± 0.13	0.32 ± 0.11	0.36 ± 0.19	^****	^**	^**	NS	NS
SPPA	SPPA_c_4	2.03 ± 1.19	2.02 ± 1.25	2.21 ± 1.22	2.27 ± 1.40	2.46 ± 1.41	NS	NS	NS	NS	NS
	SPPA_c_5	12.5 ± 3.2	12.6 ± 3.3	12.1 ± 3.0	12.0 ± 3.6	11.8 ± 3.5	NS	NS	NS	NS	NS
	SPPA_c_6	34.8 ± 5.1	34.4 ± 5.3	34.2 ± 5.0	33.8 ± 5.2	33.4 ± 5.9	NS	NS	NS	NS	NS
	SPPA_c_7	35.0 ± 5.6	35.4 ± 5.5	35.8 ± 5.7	36.6 ± 6.1	36.9 ± 7.5	NS	NS	NS	NS	NS
	SPPA_c_8	13.2 ± 2.4	13.1 ± 2.6	13.3 ± 2.6	13.1 ± 2.7	13.3 ± 3.1	NS	NS	NS	NS	NS
	SPPA_c_9	1.94 ± 1.10	1.90 ± 1.15	1.75 ± 1.25	1.63 ± 1.21	1.47 ± 1.15	^**	NS	NS	NS	NS
	SPPA_r_4	2.11 ± 0.98	2.05 ± 0.96	1.95 ± 0.96	1.90 ± 0.86	1.80 ± 0.91	NS	NS	NS	NS	NS
	SPPA_r_5	12.7 ± 2.8	12.5 ± 2.8	12.3 ± 3.0	11.9 ± 3.0	11.0 ± 4.4	^*	NS	NS	NS	NS
	SPPA_r_6	34.2 ± 4.4	34.8 ± 4.2	35.5 ± 4.0	35.9 ± 4.2	36.7 ± 4.8	^**	NS	NS	NS	NS
	SPPA_r_7	34.5 ± 5.5	34.7 ± 5.1	34.7 ± 4.8	35.3 ± 4.6	35.9 ± 5.1	NS	NS	NS	NS	NS
	SPPA_r_8	14.4 ± 3.1	13.8 ± 3.1	13.2 ± 3.2	12.5 ± 3.1	11.7 ± 4.0	^***	NS	NS	NS	NS
	SPPA_r_9	1.43 ± 0.77	1.59 ± 0.88	1.71 ± 0.75	1.79 ± 0.84	1.84 ± 0.97	^**	NS	^*	NS	NS
	SPPA_entropy	4.02 ± 0.12	4.01 ± 0.10	4.01 ± 0.13	3.99 ± 0.14	3.94 ± 0.22	^*	NS	NS	NS	NS
IA	AS1	51.1 ± 3.9	50.7 ± 3.7	50.0 ± 3.0	50.1 ± 2.9	50.2 ± 3	^*	NS	NS	NS	NS
	AS2	54.2 ± 6.2	53.5 ± 6.3	51.9 ± 6.1	52.9 ± 7.1	54.5 ± 7.8	^**	NS	^*	NS	NS
	AS3	0.03 ± 0.06	0.03 ± 0.06	0.03 ± 0.08	0.04 ± 0.11	0.06 ± 0.11	^*	NS	^*	NS	NS
ACOR and AMI	a21rr	−2.35 ± 0.29	−2.24 ± 0.31	−2.10 ± 0.32	−2.05 ± 0.33	−2.05 ± 0.37	^****	^**	^**	NS	NS
	a31rr	−1.31 ± 0.12	−1.28 ± 0.12	−1.21 ± 0.13	−1.18 ± 0.15	−1.16 ± 0.17	^****	^**	^**	NS	NS
	x2peakrr	5.79 ± 1.89	6.35 ± 2.16	7.23 ± 2.51	7.79 ± 2.94	7.35 ± 2.89	^***	^**	^**	NS	NS
	y2peakrr	0.42 ± 0.13	0.42 ± 0.12	0.45 ± 0.16	0.45 ± 0.17	0.49 ± 0.19	NS	NS	NS	NS	NS
	amax21rr	−0.50 ± 0.14	−0.46 ± 0.14	−0.40 ± 0.14	−0.37 ± 0.13	−0.39 ± 0.15	^****	^**	^**	NS	NS
	a21rrcor	−0.33 ± 0.15	−0.27 ± 0.15	−0.22 ± 0.15	−0.21 ± 0.12	−0.25 ± 0.21	^****	^**	^**	NS	NS
	a31rrcor	−0.32 ± 0.11	−0.28 ± 0.12	−0.21 ± 0.10	−0.19 ± 0.09	−0.19 ± 0.09	^****	^**	^**	NS	NS
	x2peakrrcor	6.80 ± 3.32	7.81 ± 3.81	8.90 ± 4.67	10.30 ± 5.90	9.94 ± 6.37	^**	^*	NS	NS	NS
	y2peakrrcor	0.35 ± 0.16	0.35 ± 0.16	0.34 ± 0.19	0.31 ± 0.23	0.32 ± 0.24	NS	NS	NS	NS	NS
	amax21rrcor	−0.12 ± 0.05	−0.10 ± 0.05	−0.09 ± 0.05	−0.09 ± 0.04	−0.09 ± 0.06	^***	^*	^*	NS	NS

Abbreviations: MA, method of analysis; SD, symbolic dynamic; DFA, detrended fluctuation analysis; CE, compression entropy; STSD, short-term symbolic dynamic; PPA, Poincaré plot analysis; SPPA, segmented Poincaré plot analysis; IA, irreversibility analysis; ACOR and AMI, auto-correlation and auto-mutual information; N: number of subjects; KW test: Kruskal-Wallis test; level of significance:

****p<10–20,

***p<10–10,

**p<Bonferroni criterion = 0.0007,

*p<0.01, NS, no significance.