Heart rate and heart rate variability variables (mean ± SD) of participants and statistical results.

HR = heart rate; SDNN = standard deviation of normal-to-normal beat; rMSSD = root mean squared successive differences of R-R intervals; LF = low frequency (0.04–0.15 Hz); HF = low frequency (0.15–0.40 Hz); ln = natural logarithmic transformation; DB = deep breathing. *denotes a significant difference (p<.05) between rest and post DB in case of a significant univariate interaction effect.