Ultra-Short-Term Heart Rate Variability Indexes at Rest and Post-Exercise in Athletes: Evaluating the Agreement with Accepted Recommendations

Table 1. Comparison of the ultra-short-term (i.e., < 60 sec) and short-term (i.e., 300 sec) lnRMSSD segments.

						95% CI		Limits of Agreement
	Mean (±SD), ms	p	Cohen’s d	Typical Error	ICC	Lower	Upper	Bias (± 1.96 SD)
lnRMSSD300_Pre	4.24 (.57)	-	-	-	-	-	-	-
lnRMSSD60_Pre	4.24 (.61)	.86	.01	.11	.98	.93	.99	.00 (.22)
lnRMSSD30_Pre	4.17 (.60)	.14	.12	.17	.93	.83	.97	-.07 (.41)
lnRMSSD10_Pre	4.11 (.66)	.13	.21	.34	.81	.57	.92	-.20 (.94)
lnRMSSD300_Pre	2.64(.68)	-	-	-	-	-	-	-
lnRMSSD60_Pre	2.52 (.72)	<.01	.17	.14	.96	.96	.99	-.15 (.39)
lnRMSSD30_Pre	2.53(.67)	.04	.16	.19	.93	.87	.98	-.14 (.53)
lnRMSSD10_Pre	2.56(.77)	.23	.11	.27	.90	.53	.92	-.12 (.76)

p value refers to the differences compared to the 300 second epochs, ICC = intraclass correlation coefficient, CI = 95% confidence intervals of ICC, Bias = mean difference between the criterion (i.e., 300 second) and ultra-short-term (i.e., < 60 second) values.