TABLE 2.

Within-subject correlation between sleep and nocturnal heart rate variability indices with session-rating of perceived exertion (s-RPE) and training impulse (TRIMP) during the 14 days of in-season competitive phase (n = 34).

	s-RPE			TRIMP
	r (95% Confidence Interval)	P	Description	r (95% Confidence Interval)	P	Description
Sleep duration	−0.43 (−0.53; −0.32)	<0.001	Moderate	−0.25 (−0.36; −0.12)	<0.001	Small
Sleep efficiency	−0.17 (−0.29; −0.05)	0.02	Small	−0.20 (−0.32; −0.08)	0.004	Small
lnRMSSD	0.07 (−0.05; 0.20)	0.38	Unclear	0.01 (−0.12; 0.14)	0.97	Unclear
lnLF	0.09 (−0.04; 0.21)	0.26	Unclear	0.05 (−0.07; 0.18)	0.53	Unclear
lnHF	0.01 (−0.12; 0.14)	0.97	Unclear	−0.02 (−0.14; 0.11)	0.92	Unclear

lnRMSSD, natural logarithm of square root of the mean of the sum of the squares of differences between adjacent NN intervals; lnLF, natural logarithm of low-frequency; lnHF, natural logarithm of high-frequency; LF/HF, ratio of the low to high frequency power.