## 3 Results  
The average dataset partitions utilized within the ANNs were 72.8% \(\pm\) 4.1% (training) and 27.2% \(\pm\) 4.1% (testing), with 4.1 \(\pm\) 1.5 hidden units. Model summaries showed, on average, that the accuracies of the ANNs to estimate the output variables were greater for joint/segment angles (testing rRMSE = 13.0% \(\pm\) 4.3%, \(r\) = 0.95 \(\pm\) 0.03) than for peak segment velocities (testing rRMSE = 22.1% \(\pm\) 14.7%, \(r\) = 0.91 \(\pm\) 0.07) (Table 3). Mean correlation coefficients showed excellent estimations of both groups of output variables (\(r>0.90\)) (Table 3). Joint angle estimations had the smallest range in rRMSE (4.1-20.5%), with thorax flexion/extension angle during MS being the most accurate (RMSE = 0.65\({}^{\circ}\); rRMSE = 4.1%; \(r\) = 0.98) (Table 4). However, estimations of the flexion/extension peak angular velocity during propulsion (MS-TFC) had the greatest accuracy of all output variables (RMSE = 0.24 m/s; rRMSE = 2.2%; \(r\) = 0.9) (Table 5), and performed better when the RES accelerometer peak acceleration was included over the AP. The five joint/segment angles that could be predicted with the highest accuracy were thorax flexion/extension at IFC (RMSE = 0.93\({}^{\circ}\); rRMSE = 7.6%; \(r\) = 0.98; MIIV = height) and MS (RMSE = 0.65\({}^{\circ}\); rRMSE = 4.1%; \(r\) = 0.98; MIIV = ACC Peak), pelvis flexion/extension at IFC (RMSE = 1.82\({}^{\circ}\); rRMSE = 9.6%; \(r\) = 0.95; MIIV = height) and MS (RMSE = 1.56\({}^{\circ}\); rRMSE = 9.2%; \(r\) = 0.96; MIIV = height), and hip flexion/extension at IFC (RMSE = 2.26\({}^{\circ}\); rRMSE = 9.9%; \(r\) = 0.96; MIIV = Leg length) (Figure 1). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{6}{c}{**Output Variable**} \\ \cline{2-7}
**Accelerometer Peak** & **Body Joint/Segment** & **Plane of Motion** & **Gait Phase** & **RMSE (\({}^{\circ}\))** & **rRMSE (\%)** & \(r\) \\ \hline \multirow{6}{*}{RES} & HIP & Flexion/Extension & IFC & 2.26 & 9.9\% & 0.96 \\  & KNEE & Flexion/Extension & IFC & 2.47 & 19.3\% & 0.83 \\  & THORAX & Flexion/Extension & IFC & 0.93 & 7.6\% & 0.98 \\  & THORAX & Internal/External Rotation & IFC & 1.86 & 15.0\% & 0.92 \\  & ANKLE & Flexion/Extension & MS & 2.19 & 12.2\% & 0.96 \\  & PELVIS & Flexion/Extension & MS & 1.56 & 9.2\% & 0.96 \\ \hline \multirow{6}{*}{ML} & THORAX & Internal/External Rotation & IFC & 1.46 & 11.6\% & 0.95 \\  & ANKLE & Internal/External Rotation & MS & 1.17 & 12.6\% & 0.95 \\  & SHANK & Adduction/Abduction & TFC & 2.47 & 10.9\% & 0.96 \\  & THIGH & Flexion/Extension & TFC & 3.27 & 15.8\% & 0.97 \\ \hline \multirow{6}{*}{VT} & HIP & Flexion/Extension & IFC & 1.70 & 10.0\% & 0.97 \\  & THORAX & Flexion/Extension & IFC & 1.58 & 19.5\% & 0.94 \\  & ANKLE & Flexion/Extension & MS & 1.79 & 13.6\% & 0.96 \\  & PELVIS & Flexion/Extension & MS & 1.08 & 11.5\% & 0.98 \\  & ANKLE & Internal/External Rotation & MS & 1.87 & 15.4\% & 0.96 \\ \hline \multirow{6}{*}{AP} & PELVIS & Adduction/Abduction & IFC & 2.10 & 12.7\% & 0.94 \\  & PELVIS & Flexion/Extension & IFC & 1.82 & 9.6\% & 0.95 \\ \cline{1-1}  & THORAX & Flexion/Extension & MS & 0.65 & 4.1\% & 0.98 \\ \cline{1-1}  & ANKLE & Internal/External Rotation & MS & 2.15 & 19.0\% & 0.93 \\ \cline{1-1}  & FOOT & Flexion/Extension & TFC & 2.91 & 20.5\% & 0.92 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Individual accuracy (RMSE, root-mean squared error; rRMSE, relative root-mean squared error; r, Pearson’s correlation coefficient) of the estimated joint/segment angles during testing.