Comparison between Direct Measurement and Observation Methods for Upper Extremity Activity Assessment at Workplace

直接量測與觀察法於工作現場手部作業評估之比較

10.7005/JOSH.201003.0001

陳彥廷(Yen-Ting Chen)；陳志勇(Chih-Yun Chen)；梁蕙雯(Huey-Wen Liang)；張芷茹(Tze-Ru Chang)；黃耀輝(Yaw-Huei Hwang)

肌肉骨骼不適 ； 上肢作業 ； 暴露評估 ； 觀察法 ； SI檢核表 ； HAL檢核表 ； Musculoskeletal disorder ； Upper extremity activity ； Exposure assessment ； Observation method ； Strain index checklist ； Hand activity level checklist

勞工安全衛生研究季刊

18卷1期（2010 / 03 / 01）

1 - 14

英文

To evaluate the risk factors of upper extremity musculoskeletal disorders, direct measurement has the advantage of better validity while observation method and self-report have the strength of convenience in operation. The aims of this study were to evaluate the correlation of exposure variables monitored by direct measurement and observation method, and to find out the most feasible and valid parameters by observation method to assess hand activity at workplace. A total of 35 different tasks by 19 subjects of 10 companies were included in this study, which were primarily involved in upper extremity activity. All subjects filled in a modified Nordic Musculoskeletal Questionnaire to report their health outcome prior to the beginning of this study. Then, the study subjects were asked to work as usual for the designated task for 15 minutes or more than 5 cycles per task. Meanwhile, direct measurements, including surface electromyography and biaxial electrogoniometers for wrist, were applied to record the bioelectronic signals for hand activities. All the subjects' hand activities were videotaped and, later, rated by a reviewer with Strain Index (SI) checklist and hand activity level (HAL) checklist issued by the American Conference of Governmental Industrial Hygienists. Both direct measurement and observation method provided exposure variables for exertion force and frequency. Exertion frequency obtained by direct measurement and observation method was significantly correlated (r=0.62, p＜0.01). The effort per minute estimated by SI checklist was correlated with the mean power frequency of exertion (r=0.66, p＜0.001) and the root mean square of wrist deviation speed measured by biaxial electrogoniometer (r=0.51, p＜0.01). However, such consistence was not found for exposure variable of exertion force. The findings of the present study suggested that the exertion frequency of upper extremity motion estimated by observation method could be used as a feasible indicator for physical work loading assessment at workplace if a direct measurement is not feasible for all study subjects.

To evaluate the risk factors of upper extremity musculoskeletal disorders, direct measurement has the advantage of better validity while observation method and self-report have the strength of convenience in operation. The aims of this study were to evaluate the correlation of exposure variables monitored by direct measurement and observation method, and to find out the most feasible and valid parameters by observation method to assess hand activity at workplace. A total of 35 different tasks by 19 subjects of 10 companies were included in this study, which were primarily involved in upper extremity activity. All subjects filled in a modified Nordic Musculoskeletal Questionnaire to report their health outcome prior to the beginning of this study. Then, the study subjects were asked to work as usual for the designated task for 15 minutes or more than 5 cycles per task. Meanwhile, direct measurements, including surface electromyography and biaxial electrogoniometers for wrist, were applied to record the bioelectronic signals for hand activities. All the subjects' hand activities were videotaped and, later, rated by a reviewer with Strain Index (SI) checklist and hand activity level (HAL) checklist issued by the American Conference of Governmental Industrial Hygienists. Both direct measurement and observation method provided exposure variables for exertion force and frequency. Exertion frequency obtained by direct measurement and observation method was significantly correlated (r=0.62, p＜0.01). The effort per minute estimated by SI checklist was correlated with the mean power frequency of exertion (r=0.66, p＜0.001) and the root mean square of wrist deviation speed measured by biaxial electrogoniometer (r=0.51, p＜0.01). However, such consistence was not found for exposure variable of exertion force. The findings of the present study suggested that the exertion frequency of upper extremity motion estimated by observation method could be used as a feasible indicator for physical work loading assessment at workplace if a direct measurement is not feasible for all study subjects.

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