We tested the combined effects of work schedule and task factors on upper-extremity fatigue in the laboratory during 8-h and 12-h shift schedules. Participants performed a simulated manual assembly task at three repetition rates and three torque loads and self-adjusted their work cycle duration to maintain fatigue at moderate levels. Work cycle durations decreased with increases in both load level and repetition rate. Fatigue was observed more quickly with increasing time on shifts and during night shifts compared with day shifts. Work schedule effects were most apparent at lighter workloads, with minimal differences at higher workloads. The highest fatigue levels were observed during 12-h night shifts, with similar levels reached by the end of both the week of 8-h night shifts and the week of 12-h day shifts. Overall durations were 20%–30% shorter than in previous short-term studies, which was likely a result of the more realistic work schedules used in this study. Results from this study could be applied to the design of work-rest schedules for manual tasks involving the upper extremities.
Get full access to this article
View all access options for this article.
References
1.
Anerson, H. A. (1984). Arthrosis and its relation to work. Scandinavian Journal of Work, Environment, and Health, 10, 429–433.
2.
Ayoub, M. M., Bethea, N. J., & Deivanayagam, S. (1978). Determination and modeling of lifting capacity. Grant final report submitted to the National Institute for Occupational Safety and Health.
3.
Borg, G. (1982). Psychophysical bases of perceived exertion. Medicine and Science in Sports and Exercise, 14, 377–381.
4.
Borg, G. (1990). Psychophysical scaling with applications in physical work and the perception of exertion. Scandinavian Journal of Work, Environment, and Health, 16(Suppl. 1), 55–58.
5.
Cabri, J., De Witte, B., & Clarys, J. P. (1988). Circadian variation in blood pressure responses to muscular exercise. Ergonomics, 31, 1559–1565.
6.
Ciriello, V. M., Snook, S. H., Blick, A. C., & Wilkinson, P. L. (1990). The effects of task duration on psychophysically determined maximum acceptable weights and forces. Ergonomics, 33, 187–200.
7.
Cohen, C. J., & Muehl, G. E. (1977). Human circadian rhythms in resting and exercise pulse rates. Ergonomics, 20, 475–479.
8.
Corlett, E. N., & Bishop, R. P. (1976). A technique for assessing postural discomfort. Ergonomics, 19, 175–182.
9.
Fernandez, J. E., Ayoub, M. M., & Smith, J. L. (1991). Psychophysical lifting capacity over extended periods. Ergonomics, 34, 23–32.
10.
Folkard, S., & Monk, T. H. (Eds.). (1985). Hours of work: Temporal factors in work scheduling. Chichester, England: Wiley.
11.
Hays, W. L. (1981). Statistics. (3rd ed.). New York: Holt, Rinehart & Winston.
12.
Ilmarinen, J., Ilmarinen, R., Korhonen, O. & Nurminen, M. (1980). Circadian variation of physiological functions related to physical work capacity. Scandinavian Journal of Work, Environment, and Health, 6, 112–122.
13.
Legg, S. J., & Myles, W. S. (1981). Maximum acceptable repetitive lifting workloads for an 8-hour work-day using psychophysical and subjective rating methods. Ergonomics, 24, 907–916.
14.
Legg, S. J., & Pateman, C. M. (1984). A physiological study of the repetitive lifting capabilities of healthy young males. Ergonomics, 27, 259–272.
15.
Legg, S. J., & Patton, J. F. (1987). Effects of sustained manual work and partial sleep deprivation on muscular strength and endurance. European Journal of Applied Physiology, 56, 64–68.
16.
Louhevaara, V., Hakola, T. & Ollila, H. (1990). Physical work and strain involved in manual sorting of postal parcels. Ergonomics, 33, 1115–1130.
17.
Mellor, E. F. (1986, November). Shift work and flextime: How prevalent are they?Monthly Labor Review, 109, 14–21.
18.
Mital, A. (1983). The psychophysical approach in manual lifting --A verification study. Human Factors, 25, 485–491.
19.
Putz-Anderson, V., & Galinsky, T. L. (1993). Psychophysically determined work durations for limiting shoulder girdle fatigue from elevated manual work. International Journal of Industrial Ergonomics, 11, 19–28.
20.
Rosa, R. R. (1991). Performance, alertness, and sleep after 3.5 years of 12-hour shifts: A follow-up study. Work and Stress, 5, 107–116.
21.
Rosa, R. R. (1995). Extended workshifts and excessive fatigue. Journal of Sleep Research, 4(Suppl. 2), 51–56.
22.
Rosa, R. R., & Bonnet, M. H. (1993). Performance and alertness on 8-hour and 12-hour rotating shifts at a natural gas utility. Ergonomics, 36, 1177–1193.
23.
Rosa, R. R., & Colligan, M. J. (1988). Long workdays versus restdays: Assessing fatigue and alertness with a portable performance battery. Human Factors, 30, 305–317.
24.
Rosa, R. R., & Colligan, M. J. (1992). Shiftwork: Health and performance effects. In W. N. Rom (Ed.), Environmental and occupational medicine (2nd ed., pp. 1173–1177). Boston: Little, Brown.
25.
Rosa, R. R., Colligan, M. J., & Lewis, P. (1989). Extended workdays: Effects of 8-hour and 12-hour rotating shift schedules on performance, subjective alertness, sleep patterns, and psychosocial variables. Work & Stress, 3, 21–32.
26.
Snook, S. S. (1978). The design of manual handling tasks. Ergonomics, 21, 963–985.
27.
Waersted, M. & Westgaard, R. H. (1991). Working hours as a risk factor in the development of musculoskeletal complaints. Ergonomics, 34, 265–276.
28.
Wojtczak-Jaroszowa, J. (1977). Physiological and psychological aspects of night and shift work (DHEW NIOSH Tech. Report 78-113). Cincinnati, OH: National Institute for Occupational Safety and Health.
29.
Wojtczak-Jaroszowa, J., & Banaszkiewicz, A. (1974). Physical work capacity during the day and at night. Ergonomics, 17, 193–198.
30.
Yoshitake, H. (1978). Three characteristic patterns of subjective fatigue symptoms. Ergonomics, 21, 231–233.
31.
Yu, Y. & Lu, S. (1990). The acceptable load while marching at a speed on 5 km/hr for young Chinese males. Ergonomics, 33, 885–890.
32.
Zhu, Z. & Zhang, Z. (1990). Maximum acceptable repetitive lifting workload by Chinese subjects. Ergonomics, 33, 875–884.
