Table 4.

Multivariate regression analyses for the Rivermead Post-Concussion Symptom Questionnaire (RPQ) ^a.

	Subacute RPQ Symptom Domain
	Somatic			Emotional			Cognitive
HRV Variable	β	sR2	p	β	sR2	p	β	sR2	p
Resting State
HR dispersion	0.180	0.027	0.200	0.355	0.104	0.009 *	0.341	0.097	0.016 *
SDNN	−0.308	0.082	0.023 *	0.101	0.009	0.463	−0.024	0.000	0.870
RMSSD	−0.293	0.072	0.033 *	0.114	0.011	0.413	−0.042	0.001	0.774
SampEn	0.169	0.023	0.238	−0.180	0.026	0.205	−0.081	0.005	0.584
Isometric Handgrip Contraction
HR dispersion	0.012	0.000	0.929	0.240	0.055	0.064	−0.161	0.025	0.232
SDNN	−0.163	0.024	0.226	0.154	0.021	0.253	−0.120	0.013	0.391
RMSSD	−0.047	0.002	0.726	0.212	0.042	0.109	−0.077	0.005	0.576
	Post-Acute RPQ Symptom Domain
Resting State
HR dispersion	−0.002	0.000	0.986	0.046	0.002	0.735	0.124	0.013	0.380
SDNN	0.024	0.001	0.851	0.001	0.000	0.993	−0.009	0.000	0.948
RMSSD	0.073	0.005	0.573	0.066	0.004	0.627	0.033	0.001	0.815
SampEn	−0.047	0.001	0.725	−0.018	0.000	0.898	0.034	0.001	0.820
Isometric Handgrip Contraction
HR dispersion	0.007	0.000	0.954	−0.028	0.001	0.826	−0.045	0.002	0.736
SDNN	0.026	0.001	0.837	−0.003	0.000	0.981	−0.053	0.003	0.701
RMSSD	0.033	0.001	0.794	−0.013	0.000	0.920	−0.009	0.000	0.945

^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.