Table 9.

Multivariate regression analyses for One-Back task (ONB) ^a.

	Subacute Cognitive Performance (ONB)
	ONB Mean RT (ms)			ONB RT Variability			ONB Accuracy (%)
HRV Variable	β	sR2	p	β	sR2	p	β	sR2	p
Resting State
HR dispersion	0.052	0.002	0.666	0.495	0.203	0.001 *	−0.298	0.074	0.049 *
SDNN	0.061	0.003	0.611	0.218	0.041	0.126	−0.271	0.063	0.068
RMSSD	0.077	0.005	0.523	0.185	0.029	0.201	−0.212	0.038	0.160
SampEn	−0.095	0.007	0.438	−0.122	0.012	0.412	0.313	0.079	0.041 *
Isometric Handgrip Contraction
HR dispersion	0.090	0.008	0.424	0.402	0.154	0.002 *	−0.195	0.036	0.169
SDNN	0.150	0.020	0.194	0.252	0.057	0.069	−0.175	0.028	0.233
RMSSD	0.241	0.054	0.032 *	0.343	0.108	0.011 *	−0.174	0.028	0.229
	Post-acute Cognitive Performance (ONB)
Resting State
HR dispersion	−0.098	0.008	0.492	−0.010	0.000	0.948	−0.373	0.118	0.008 *
SDNN	0.175	0.026	0.215	0.042	0.001	0.780	−0.206	0.037	0.149
RMSSD	0.186	0.029	0.192	0.066	0.003	0.667	−0.156	0.021	0.280
SampEn	−0.278	0.062	0.055	0.040	0.001	0.800	0.119	0.011	0.427
Isometric Handgrip Contraction
HR dispersion	0.213	0.043	0.109	0.066	0.004	0.649	−0.319	0.097	0.016 *
SDNN	0.278	0.070	0.042 *	0.037	0.001	0.804	−0.177	0.028	0.205
RMSSD	0.328	0.099	0.014 *	0.055	0.003	0.707	−0.230	0.049	0.094

^a Age, sex, history of concussion, BMI, time since injury, and athletic status were entered into adjusted models. * denotes predictor significance (p < 0.05). sR², squared semi-partial correlations. Abbreviations: RT, reaction time; 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.