# Visualization of Caregiving Posture and Risk Evaluation of Discomfort and Injury
### Literature Review  
Comprehensive ergonomics assessment methods have a great effect in avoiding musculoskeletal discomfort and injury [7]. Compared with other ergonomics assessment methods [8; 9], the Rapid Entire Body Assessment (REBA) [10] is a postural load assessment method that covers the entire body, and it is based on the workers' posture, joint angles, and muscle loads, mapping these factors to a specific scoring table to determine the risk level of working postures and provide improvement suggestions for reducing potential health problems. Also, REBA is generally applicable for posture risk assessment in a wide range of occupations, such as forestry timber harvesting [11; 12], mining industries [13], quarry industries [14], and especially in nursing [15]. REBA is more suitable for the assessment of hospital nursing activities [16]. Utilizing the REBA method to assess the postures of nurses in the operating room contributes to the mitigation of musculoskeletal disorders [17; 18]. REBA also showed good guidance with respect to musculoskeletal risks in a sample of emergency medical technicians [19]. Some researchers believed that REBA has a good reference significance in the assessment of inappropriate posture by dentists [20; 21]. The REBA method was also reported to evaluate caregiving tasks with assistive devices, where the risk of musculoskeletal disorders could be assessed [22]. Furthermore, the reliability of REBA has been confirmed compared with other traditional methods [23]. In our research, REBA was selected because it considers all body parts as well as all well-known awkward postures, loads, and types of activity. However, some studies have pointed out that there is an overassessment of risk by REBA in certain scenarios [24]. To make REBA more suitable in our caregiving scenario, we explored the differences from several objective standpoints, and we adjusted REBA's rules based on these differences.  
It is common knowledge in daily life that if you support the center of gravity (COG) you can support the gravity of each part. The COG is crucial for maintaining balance and stability during physical activities like walking, running, and sports [25; 26]. It also plays a vital role in optimizing design for safety and efficiency in fields such as ergonomics, industrial design, and rehabilitation [27]. During lifting tasks, the body needs to complete a transfer from a lower position to a higher position. To maintain the body's balance, the COG of the standing posture will be systematically lowered [28]. Simultaneously, maintaining an upright posture in the upper body allows for minimal muscle activation and enhances postural stability [29]. This helps alleviate pressure on the waist and reduces the risk of musculoskeletal disorders.  
Experienced caregivers, through extensive training, have acquired familiarity with optimal postures and positions. This expertise allows them to adopt power positions that help prevent musculoskeletal injuries. Power position refers to the optimal physical position and body pose to maintain balance and maximize strength output during lifting activities, thus preventing muscular injury [30]. Experienced caregivers often change the COG's height to achieve power positions with the minimal physical strain. There is a certain correlation between the height of the trunk bending and the posture instability, and bearing loads in a tilted manner would cause further body instability [31]. The power position is very important for caregiving tasks. Most of the previous studies have only applied the REBA rules in the assessment of caregiving posture, ignoring the relationship between COG changes and power positions. Therefore, incorporating COG and power positions into the REBA score holds the potential to make it more applicable to the caregiving process.