## 2 Methods
### Experiment  
In this study, motion capture experiments were conducted with healthy participants at Kwansei Gakuin University from 20 February 2019 to 24 February 2019 and with rehabilitation patients at Toyonaka Heisei Hospital on 7 March 2020. The 40 motion capture markers were placed on landmarks throughout the body [18]. In this study, four markers (the lateral ankle, the lateral 1/3 of the lower tibia, the lateral epicondyle of the knee, and the lateral 1/3 of the lower thigh) were placed on one lower extremity, and participants sat in a chair with a height of 43.5 cm and without a backrest. Participants were instructed to not allow their upper limbs to come into contact with their body or the external environment during the STS movement. The motion capture experiment was conducted as follows (Figure 1). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Group** & **Code** & **Gender** & **Age** & **Height** & **Weight** & **BMI** & **Muscle** & **Body Fat** \\  & & & & **(cm)** & **(kg)** & & **(kg)** & **(\%)** \\ \hline \multirow{3}{*}{Health (N 1 = 4)} & H-1 & Male & 22 & 169.0 & 54.0 & 18.9 & 42.3 & 17.3 \\  & H-2 & Male & 22 & 176.0 & 81.8 & 26.4 & 59.7 & 23.1 \\ (N 1 = 4) & H-3 & Male & 22 & 172.0 & 68.4 & 23.1 & 49.8 & 23.3 \\  & H-4 & Male & 22 & 177.0 & 67.6 & 21.6 & 49.2 & 23.2 \\  & Mean \(\pm\) SD 2 & & 22.3\(\pm\)0.5 & 173.5\(\pm\)3.7 & 67.9\(\pm\)11.4 & 22.5\(\pm\)3.1 & 50.2\(\pm\)7.2 & 21.7\(\pm\)3.0 \\ \hline \multirow{3}{*}{Patient} & P-1 & Male & 86 & 139.0 & 48.8 & 25.2 & 27.7 & 40.3 \\  & P-2 & Female & 78 & 165.5 & 40.3 & 14.7 & 35.6 & 6.5 \\ (N = 4) & P-3 & Female & 81 & 156.0 & 56.0 & 23.0 & 33.9 & 36.0 \\  & P-4 & Female & 86 & 134.5 & 33.0 & 18.2 & 23.1 & 27.2 \\ \cline{1-1}  & Mean \(\pm\) SD & & 82.8 \(\pm\) 3.1 & 148.8 \(\pm\) 11.2 & 44.5 \(\pm\) 7.8 & 20.3 \(\pm\) 3.7 & 30.1 \(\pm\) 4.5 & 27.5 \(\pm\) 11.6 \\ \hline \hline \end{tabular}  
* Number of participants. 2 Standard deviation  
\end{table} 
Table 1: Summary of the participants’ physical information. Figure 1: STS measurement experiment. The upper extremity did not touch the body or the outside environment. The plantar was fixed in an arbitrary position that was not interchanged from the beginning to the end of the STS motion. (**a**) The start of the STS motion from the stationary starting posture at the signal, (**b**, **c**) the STS motion in progress, and (**d**) the end of the STS motion when the ending posture is stationary. 1. Each participant sat in a chair and maintained their posture to initiate the STS movement. 2. When we judged that the participant's sitting posture was stationary, we signaled the start of STS. 3. On hearing the cue, the participant initiated the STS movement. 4. When the participant stood up and we judged that the standing posture was stationary, we signaled the end of the STS movement. 5. The video images from the cue for the start of the movement to the cue for the end of the movement were included in the analysis. A calibration space with an area of 150 cm \(\times\) 150 cm and a height of 195 cm centered on the participant's feet was set up (Figure 2). The captured images were recorded using Capture-Ex (Library Co., Ltd., Tokyo, Japan) at a sampling frequency of 50 Hz. Move-tr/3D (Library Co., Ltd., Tokyo, Japan) was used to convert the marker information in the video into coordinate data, and KineAnalyzer (KISSEI COMTEC Co., Ltd., Nagano, Japan) was used to measure the EAs of the thigh and shank. A 2 Hz low-pass filter was applied to all marker data. The EA formed by the shank and the vertical axis was defined as \(\theta_{S}\), and the EA formed by the thigh and the vertical axis was defined as \(\theta_{T}\) (Figure 3). Figure 3: Definition of EAs for the thigh and the lower leg. The EA was measured using KineAnalyzer. The angle between the vertical axis and the thigh axis was defined as \(\theta_{T}\), and the angle between the vertical axis and the lower leg was defined as \(\theta_{S}\). Figure 2: Experimental setup.