Table 2. Results of mixed ANOVA with Tuckey’s multiple comparisons, with associated p-values of the HRV during REST, T0, T12 and T24, of the 23 subjects that performed the morning (8.00 a.m.) and the evening (8.00 p.m.) HIIT. Data are means (±SD).

	HR (b·min-1)	LnRMSSD (ms)	LnLF power (ms2)	LnHF power (ms2)	LF power (n.u.)	HF power (n.u.)	>1 DFA
Morning (n = 23)
Rest	55(8)	4.2 (.4)	7.4 (.8)	7.2 (.7)	70.7 (14.5)	29.3 (14.5)	1.0 (.2)
T0	60(7)	4.0 (.4)	7.9 (.5)	7.7 (.9)	70.5 (16.4)	42.6 (20.0)	1.2 (.2)
T12	60(5)	4.1 (.3)	7.4 (.6)	7.4 (.6)	58.9 (18.4)	41.1 (18.4)	1.0 (.2)
T24	54(7)	4.2 (.3)	7.9 (.7)	7.2 (.7)	67.6 (12.7)	32.4 (12.8)	1.2 (.2)
Evening (n = 23)
Rest	57(7)	4.2 (.3)	7.5 (.9)	7.1 (.6)	70.7 (14.5)	31.1 (13.1)	1.1 (.2)
T0	67(8)	3.7 (.3)	8.8 (.7)	6.8 (.6)	79.3 (7.2)	42.6 (20.0)	1.4 (.3)
T12	57(7)	4.2 (.4)	7.8 (.7)	7.2 (.8)	65.2 (15.9)	39.7 (15.8)	1.1 (.2)
T24	57(6)	4.2 (.4)	7.6 (.7)	7.0 (.2)	63.9 (13.4)	32.4 (12.7)	1.1 (.2)
Interaction	p = .010	p = .012	p = .001	p = .002	p =.017	n.s.	p = .014
Effect of time	p < .0001	p < .0001	p < .0001	p = .040	p = .002	n.s.	p = .022
Morning vs Evening	p = .029	p = .048	p = .004	p = .049	p = .021	n.s.	p < .0001

HR: heart rate; RMSSD: square root of the mean of the sum of the squares of differences between adjacent normal R–R intervals; LF: low frequencies; HF: high frequencies; DFA: detrended fluctuation analysis; n.s.: not significant