Table 6.

Multivariate regression analyses for the Behavior Rating Inventory of Executive Function (BRIEF-P) ^a.

	Subacute BRIEF-P Index
	Behavioral Regulation Index			Metacognition Index
HRV Variable	β	sR2	p	β	sR2	p
Resting State
HR dispersion	0.010	0.000	0.948	0.071	0.004	0.627
SDNN	0.334	0.096	0.017 *	0.102	0.009	0.476
RMSSD	0.303	0.078	0.034 *	0.080	0.005	0.580
SampEn	−0.376	0.114	0.009 *	−0.126	0.013	0.392
Isometric Handgrip Contraction
HR dispersion	0.196	0.036	0.149	0.210	0.042	0.117
SDNN	0.133	0.016	0.345	0.019	0.000	0.893
RMSSD	0.068	0.004	0.628	−0.038	0.001	0.784
	Post-Acute BRIEF-P Index
Resting State
HR dispersion	0.058	0.003	0.691	0.122	0.013	0.424
SDNN	−0.039	0.001	0.784	−0.130	0.015	0.387
RMSSD	−0.010	0.000	0.946	−0.132	0.015	0.387
SampEn	−0.045	0.002	0.764	0.025	0.000	0.875
Isometric Handgrip Contraction
HR dispersion	0.015	0.000	0.914	0.011	0.000	0.940
SDNN	−0.062	0.003	0.661	−0.161	0.023	0.276
RMSSD	0.001	0.000	0.995	−0.133	0.016	0.359

^a Age, sex, history of concussion, BMI, time since injury, and athletic status were entered into the adjusted models. * denotes predictor significance (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.