# Visualization of Caregiving Posture and Risk Evaluation of Discomfort and Injury
## 2 Materials and Methods  
### Study Design  
The daily work in the caregiving industry is individualized and involves many complex working postures. Patient transfer, one of the most common postures in the caregiving, was chosen for our research. Subjects were recruited by convenience sampling, and the subjects were selected based on the following criteria:  
Eight professional nurses from the Department of Rehabilitation Therapy at the co-authors' hospital were invited and served as the experienced group (Exp group). The inclusion criteria for the Exp group were as follows: (1) aged between 25 and 35 years, (2) at least 5 years of professional caregiving experience, and (3) no history of back injury or pain in the past year [32].  
Ten inexperienced volunteers were recruited. The inclusion criteria for the inexperienced group (Inexp group) were as follows: (1) aged between 20 and 35 years, (2) without any caregiving experience, and (3) no history of back injury or pain in the past year.  
One nurse at the co-authors' hospital acted as the patient (age: 30 years, height: 168 cm, weight: 62 kg). Another 8 nurses (Exp group) and 10 volunteers (Inexp group) were requested to transfer the patient from bed to a wheelchair. The sitting posture and movements of the patient were kept consistent. Their age, height, and weight are shown in Table 1.  
The Intel RealSense Depth Camera D435 was used to capture the caregiving posture, and the kinematic analysis system based on the OPENPOSE algorithm was used to obtain skeletal joint data. OPENPOSE-based ergonomic assessments were robust to non-ideal task conditions [33]. The COG trajectory calculation method employed in this study was adapted from the works of [PERSON] et al. and [PERSON] et al. [34; 35].  
A previous study proved that the Wii Balance Board is a valid tool for assessing standing balance [36]. Two Wii Balance Boards (Nintendo Co., Ltd., Kamitoba Hokodatecho, Minami-ku, Kyoto, Japan) were used to measure the ground reaction forces of each foot and then calculate the trajectories of the center of pressure (COP). Each participant (Exp group, \(n=8\); Inexp group, \(n=10\)) was asked to stand on the Wii Balance Board and adjust their suitable caregiving postures. The distance between the feet of each participant was measured before starting. To analyze and refine the entire patient transfer process, the patient transfer caregiving process was divided into the following 5 stages (Figure 1):  
Stage 1: The caregiver placed their hands in a hugging position around the patient's waist, adjusted their posture, and prepared to start.  
Stage 2: The caregiver began to lift the patient and prepared to take them from the support of the bed.  
Stage 3: The caregiver lifted the patient to the proper point and prepared to rotate the patient to the side of the wheelchair.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Demographic** & **Exp Group (\(n=8\))** & **Inexp Group (\(n=10\))** & \(p\)**-Value** \\ \hline Age & 29.125 \(\pm\) 3.48 & 26.9 \(\pm\) 6.11 & 0.348 \\ Weight (kg) & 61.06 \(\pm\) 9.5 & 62.97 \(\pm\) 7.73 & 0.644 \\ Experience (years) & 6.25 \(\pm\) 3.15 & 0 & \textless{}0.001 \\ Height (cm) & 167.5 \(\pm\) 4.84 & 169.89 \(\pm\) 5.07 & 0.328 \\ \hline \end{tabular}
\end{table}
Table 1: Demographics of the participants.