Pace of Work and Its Effects on the Musculoskeletal System

工作頻率對於肌肉骨骼系統之影響

鄔蜀文(Shu-Wen Wu) ； 鄔蜀芳(Su-Fang Wu)

《大仁學報》 37期 (2010/09) Pp. 49-61

https://doi.org/10.29707/TJ.201009.0004

摘要

Objective: Excessive pace is a major cause of upper limb work-related musculoskeletal disorders. To maximize output while minimizing disability, it is useful to establish an acceptable pace of industrial workers at a given task. Our aim is to provide objective evidence to assist those searching of the most suitable pacing of repetitive work. Methods: 30 volunteers performed a repetitive task of scooping and pouring at different duration and pacing speeds. As an index of upper limb function, grip strength (Maximal Volitional contraction, MVC), was measured by Micro FETE4 dynamometer. The statistical data were analyzed by repeated measure design and paired t-test, using SPSS 12.0 software. Results: Duration of task caused decline in grip strength (p＜0.01), as anticipated. Increasing pace, however, produced unexpected results that seemed paradoxical. In females, when pace was increased to a critical level (25 cycles/minute), the grip strength was found to show a transient increase. While males did not show this at the pace noted for females, they did show a similar effect when pace was further increased (35 cycles/minute). Conclusions: These results are counter-intuitive: one would expect grip strength to decline as one became tired or stressed. We suggest that this transient increase in grip strength is a mark of ”critical threshold” pace, and approaching strain, indicating reflex activating of extra cardiovascular reserves in response to a taxing pace. Measurements of grip strength by dynamometer are simple and useful complement to ergonomic checklist, such as Rapid Upper Limb Assessment (RULA), in helping those responsible for industrial health and safety when planning optimal working pace.

關鍵字

肌肉骨骼傷病 ； 握力 ； 頻率 ； 持續工作量

並列摘要

Objective: Excessive pace is a major cause of upper limb work-related musculoskeletal disorders. To maximize output while minimizing disability, it is useful to establish an acceptable pace of industrial workers at a given task. Our aim is to provide objective evidence to assist those searching of the most suitable pacing of repetitive work. Methods: 30 volunteers performed a repetitive task of scooping and pouring at different duration and pacing speeds. As an index of upper limb function, grip strength (Maximal Volitional contraction, MVC), was measured by Micro FETE4 dynamometer. The statistical data were analyzed by repeated measure design and paired t-test, using SPSS 12.0 software. Results: Duration of task caused decline in grip strength (p＜0.01), as anticipated. Increasing pace, however, produced unexpected results that seemed paradoxical. In females, when pace was increased to a critical level (25 cycles/minute), the grip strength was found to show a transient increase. While males did not show this at the pace noted for females, they did show a similar effect when pace was further increased (35 cycles/minute). Conclusions: These results are counter-intuitive: one would expect grip strength to decline as one became tired or stressed. We suggest that this transient increase in grip strength is a mark of ”critical threshold” pace, and approaching strain, indicating reflex activating of extra cardiovascular reserves in response to a taxing pace. Measurements of grip strength by dynamometer are simple and useful complement to ergonomic checklist, such as Rapid Upper Limb Assessment (RULA), in helping those responsible for industrial health and safety when planning optimal working pace.

並列關鍵字

Musculoskeletal Disorders MSDs ； grip strength ； pace ； work duration

參考文獻

Ciriello, V. M.. “The effects of container size, frequency and extended horizontal reach on maximum acceptable weights of lifting for female industrial workers”. Appl Ergon (2007)38:1-5.

Brain, N. C., Jerome, J. C., Carter, J. K., et al. “A prospective filed study of the relationship of potential occupational risk factors with occupational injury/illness”. AIHA (2003), 64:376-87.

Institute of Occupational Safety and Health (IOSH). Occupational Musculoskeletal Disorders Checklist. Taipei: IOSH, (2003), 92-T049. [in Chinese]

Yeung, S. S., Genaidy, A. M., Deddens, J., Leung, P. C.. “What is a demanding lifting job for manual handling workers in Hong Kong?” Ergon (2003), 46:574-97.

Pope, D. P., Silman, A. J., Cherry, N. M., Pritchard, C., Macfarlane, G. J.“Association of occupational physical demands and psychosocial working environment with disabling shoulder pain”. Ann Rheumatic diseases (2001) 60:852-8.