# Inter-Session Repeatability of Marker-Less Motion Capture of Treadmill Running Gait
## 3 Results
### Reliability of Discrete Metrics
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline  & \multicolumn{6}{c}{**Initial Foot Contact.**} & \multicolumn{6}{c}{**SEM**} & \multicolumn{1}{c}{**MDC**} \\ \hline  & \multicolumn{3}{c}{**Mean (SD) [Deg.]} & \multicolumn{3}{c}{**ICC\({}_{3,1}\)**} & \multicolumn{3}{c}{**95\% CI**} & \multicolumn{1}{c}{**SEM**} & \multicolumn{1}{c}{**MDC**} \\  & \multicolumn{1}{c}{**Day 1**} & \multicolumn{1}{c}{**Day 2**} & \multicolumn{1}{c}{**Day 3**} & \multicolumn{1}{c}{**ICC\({}_{3,1}\)**} & \multicolumn{1}{c}{**Lower**} & \multicolumn{1}{c}{**Upper**} & \multicolumn{1}{c}{**[Deg.]**} & \multicolumn{1}{c}{**[Deg.]**} \\ \hline
**Ankle** & & & & & & & & & & & \\ Dorsiflexion & \(-0.2\) & (6.1) & 0.5 & (5.8) & \(-0.1\) & (6.2) & 0.936 & 0.904 & 0.958 & 1.31 & 3.6 \\ Rearfoot Inversion & 8.3 & (2.4) & 7.9 & (2.4) & 8.3 & (3.1) & 0.721 & 0.613 & 0.809 & 0.58 & 1.6 \\ External Rotation & 10.8 & (3.1) & 11.4 & (2.7) & 10.3 & (3.3) & 0.734 & 0.630 & 0.819 & 0.66 & 1.8 \\
**Knee** & & & & & & & & & & & \\ Flexion & 15.9 & (3.6) & 15.9 & (3.7) & 15.8 & (3.6) & 0.881 & 0.826 & 0.922 & 0.80 & 2.2 \\ Adduction & 0.0 & (1.8) & 0.1 & (1.9) & 0.1 & (2.2) & 0.908 & 0.864 & 0.940 & 0.43 & 1.2 \\ Internal Rotation & 15.7 & (4.8) & 16.5 & (3.9) & 16.1 & (4.2) & 0.791 & 0.704 & 0.860 & 0.94 & 2.6 \\
**Hip** & & & & & & & & & & & \\ Flexion & 24.9 & (3.8) & 24.9 & (3.8) & 25.1 & (4.4) & 0.862 & 0.800 & 0.909 & 0.88 & 2.4 \\ Adduction & 8.0 & (1.4) & 7.7 & (1.6) & 8.0 & (1.8) & 0.745 & 0.644 & 0.827 & 0.35 & 1.0 \\ Internal Rotation & 2.7 & (2.3) & 2.9 & (2.4) & 3.0 & (2.5) & 0.688 & 0.572 & 0.785 & 0.52 & 1.4 \\
**Pelvis** & & & & & & & & & & & \\ Anterior Tilt & 4.0 & (3.5) & 4.0 & (2.7) & 4.3 & (3.4) & 0.781 & 0.691 & 0.853 & 0.70 & 1.9 \\ Drop & 2.3 & (1.1) & 2.1 & (1.1) & 2.5 & (1.3) & 0.674 & 0.555 & 0.774 & 0.26 & 0.7 \\ Ipsilateral Rotation & 3.6 & (2.8) & 3.6 & (2.9) & 3.7 & (2.9) & 0.855 & 0.790 & 0.904 & 0.62 & 1.7 \\
**Trunk** & & & & & & & & & & & \\ Forward Lean & 7.7 & (4.2) & 7.8 & (4.6) & 7.9 & (4.3) & 0.956 & 0.934 & 0.972 & 0.95 & 2.6 \\ Ipsilateral Flexion & \(-1.3\) & (1.7) & \(-1.3\) & (2.0) & \(-1.2\) & (1.9) & 0.931 & 0.898 & 0.956 & 0.40 & 1.1 \\ Ipsilateral Rotation & 13.9 & (3.6) & 14 & (3.9) & 13.9 & (3.7) & 0.952 & 0.928 & 0.969 & 0.81 & 2.3 \\ \hline  & & & & & & & & & & & \\ \end{tabular}
\end{table} 
Table 3: Reliability of key kinematic metrics at initial foot contact across three distinct sessions and three distinct speeds in 21 runners. At toe off, all kinematic metrics in the sagittal plane demonstrated excellent reliability (ICC range: 0.917-0.956), except for the hip and pelvis variables (ICC = 0.659, 0.669) (Table 5). All kinematic metrics in the frontal plane demonstrated either good or excellent reliability (ICC range: 0.831-0.911), except for the ankle variable (ICC = 0.644). All kinematic metrics in the transverse plane demonstrated either good or excellent reliability (ICC range: 0.827-0.940), except for the ankle and hip variables (ICC = 0.501, 703). Across all planes, SEM values were low (<0.4\({}^{\circ}\)), averaging 0.27\({}^{\circ}\).