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