Table 3.

Correlations Between HRV, HRR, and Exercise Performance (n = 91).

	Maximum heart rate achieved (Bpm)	Maximum speed achieved (mph)	Maximum incline achieved (%)	METs
SDNN (ms)	0.080 (−0.064)	0.280** (0.178)	0.256** (0.161)	0.284** (0.181)
SDNN index (ms)	0.262* (0.048)	0.422** (0.264*)	0.377** (0.216*)	0.394** (0.218*)
RMSSD (ms)	−0.073 (−0.257*)	0.043 (−0.108)	0.044 (−0.113)	0.031 (−0.130)
NN50 (%)	0.251* (−0.026)	0.358** (0.185)	0.316** (0.144)	0.333** (0.138)
HRR (bpm)	0.158 (0.045)	0.238* (0.129)	0.247* (0.136)	0.288** (0.192)

Note. *denotes significance value <0.05; **denotes significance values <0.01; () values reflect Spearman correlations adjusted for the following covariates: age, race (white/non-white), gender (male/female), body mass index (BMI).