上肢累積性工作傷害對人員產生的影響及衍生的社會成本均十分可觀，而主觀不舒適感受可視為工作傷害的預兆，因此本研究以主觀不舒適感受做為工作負荷的評量指標，進而建立一個主觀不舒適預測模型，除了可預防上肢累積性傷害的發生，進一步更可提高人員的工作滿意度。
本研究針對上肢的握持動作進行模擬實驗，以主觀及客觀方法評估其工作負荷，實驗因變項計有高度(肩高、水平伸直的手臂向上屈曲30o時的手高、水平伸直的手臂向下屈曲30o時的手高)、距離(上肢最遠握持距離、上肢最遠握持距離的0.6倍)、負重(0.86kg、1.12kg)、頻率(2/分鐘、4/分鐘)與持續時間(5分鐘、10分鐘)，共有48種不同工作負荷的實驗組合，每種實驗組合執行時間為60秒。本實驗有15位男性與15位女性參與，實驗期間均紀錄受試者的肌電訊號反應(斜方肌、三角肌、三頭肌、二頭肌、屈指肌)、動作速度表現(公分/秒)、關節活動度(頸關節、肩關節、肘關節、腕關節)，而後以Category partition scale (CP-50)進行全身與身體各部位主觀不舒適程度之評比。
由實驗結果得知，男性與女性在主觀評估造成工作負荷的因子並不相同，女性對於高頻率的動作較容易感到不舒適，而造成男性不舒適感的主要因子為握持高度。本研究建立之標準化男性與女性不舒適評比迴歸模型的判定係數分別為0.7與0.76，因此只要蒐集握持高度、距離、重量、頻率，及持續時間等變數資訊，應用本研究之迴歸模型即可有效預測出人員主觀不舒適程度。

Cumulative trauma disorders (CTDs) have a great impact on the health and safety of workers. By using subjective discomfort rating to evaluate workload, improper designs of work can be improved. It can both prevent workers from CTD of the upper limbs and enhance job satisfactions.
In the experiment, we considered the combination of holding height (shoulder height, hand heights of flexion and extension 30o from shoulder height), load (0.86 kg and 1.12 kg), frequency (2 times/min. and 4 times/min.) and duration (5 sec. and 10 sec.) of motion to simulate the 48 holding tasks. Fifteen male and fifteen female voluntary subjects executed each experiment condition for 60 seconds, then conducted discomfort ratings of whole body and local body parts. At the same time, rapid upper-limb assessment (RULA), EMG, range of joints motion and speed of motion were collected to compare with the discomfort ratings.
The results of the analysis of discomfort ratings showed that male subjects differed significantly from female subjects. The male subjects had the highest discomfort feeling in target height over shoulder, but the female subjects in high frequency of motion. For the constructed discomfort prediction models for holding tasks, the coefficients of determination (R2) for males and for females were 0.7 and 0.76. The models can provide a convenient and efficient tool to predict one’s subjective discomfort with the parameters including holding height and distance, load, frequency and duration time.

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