Table 5.

Multivariate regression analyses for the Beck Youth Inventory–Depression Scale (BYI-2) ^a.

	Subacute BYI-2 Scores			Post-Acute BYI-2 Scores
HRV Variable	β	sR2	p	β	sR2	p
Resting State
HR dispersion	−0.031	0.000	0.840	0.024	0.000	0.867
SDNN	−0.107	0.010	0.474	0.098	0.008	0.482
RMSSD	−0.073	0.004	0.632	0.132	0.015	0.345
SampEn	−0.002	0.006	0.569	−0.112	0.010	0.438
Isometric Handgrip Contraction
HR dispersion	−0.019	0.000	0.892	0.030	0.001	0.820
SDNN	−0.055	0.003	0.706	0.051	0.002	0.709
RMSSD	0.051	0.002	0.724	0.031	0.008	0.820

^a Age, sex, history of concussion, BMI, time since injury, and athletic status were entered into the adjusted models. No significance was observed (p > 0.05). sR², squared semi-partial correlations. Abbreviations: HRV, heart rate variability; HR, heart rate; SDNN, standard deviation of NN intervals; RMSSD, root mean square of successive NN interval differences; and SampEn, sample entropy.