Table 2.

Intra-class correlations between short-term and ultra-short-term measures of heart rate variability.

	Female participants		Male participants
	ICC	95% CI	ICC	95% CI
Log-HF-HRV-300 vs.Log-HF-HRV-120	0.946	[0.896, 0.972]	0.961	[0.926, 0.980]
Log-HF-HRV-300 vs. Log-HF-HRV-60	0.878	[0.764, 0.937]	0.931	[0.829, 0.968]
Log-HF-HRV-120 vs. Log-HF-HRV-60	0.974	[0.935, 0.988]	0.949	[0.901, 0.974]

Note. ICC = intra-class correlations, 95% CI = 95% confidence interval, Log-HF-HRV-300 = log-transformed high frequency heart rate variability derived from short-term HR recordings (300 s), Log-HF-HRV-120 = log-transformed high frequency heart rate variability derived from ultra-short-term HR recordings (120 s), Log-HF-HRV-60 = log-transformed high frequency heart rate variability derived from ultra-short-term HR recordings (60 s).