Table 2.

Results for the models Gradient Boosting Regression Tree (GBRT), SVM with Linear (SVRL) and Radial Basis Function (SVRR), and Random Forest (RF) for using either solely IMU data or a combination of IMU and HRV data.

	${\mathit{R}}^2$		MSE
Model	IMU	IMU + HRV	IMU	IMU + HRV
GBRT	$-0.01$ ± $0.12$	$0.48$ ± $0.30$	$2.14$ ± $0.49$	$1.45$ ± 0.44
SRVL	$-0.03$ ± $0.13$	$0.40$ ± $0.18$	$2.19$ ± $0.59$	$1.71$ ± 0.67
SVRR	$-0.05$ ± $0.26$	$0.22$ ± $0.19$	$2.24$ ± $0.81$	$1.89$ ± 0.49
RF	$0.08$ ± $0.10$	$0.52$ ± $0.06$	$2.09$ ± $0.64$	$1.51$ ± 0.45