Shift Work and Exercise

Physical Activity Behaviors during Shift Work

Workers and their families can alter their habits to cope with the disruption to domestic life that is associated with shift work, although women shift workers seem to have particular problems in balancing their work and domestic lives. Unlike the malleable domestic environment, organized leisure activities and training sessions for sports clubs are generally scheduled in the early evening and weekends to accommodate the day-working majority. This scheduling conflict makes it very difficult for the shift worker to participate in organized activities and has been found to contribute to the decision of some people to leave shift work altogether. Those shift workers who enjoy solitary or individual activities are probably not so disadvantaged. Individual shift workers who join fitness and health clubs can enjoy the benefits of “off-peak” membership costs and can use the facilities at less crowded times. Activities such as cycling, swimming, and jogging can also be carried out on an individual basis in the shift worker's own spare time. Nevertheless, organized competitions in these sports are still normally scheduled in the weekend, when it is more likely that a shift worker is at work. Moreover, the transient negative experiences of exercising while partially deprived of sleep and at times that are out of kilter with the “body clock” (e.g., in the early morning) might be perceived to be significant enough for the shift worker to stop these individual activities. Such attrition at an early stage in an exercise program would be unfortunate since there are, as discussed below, likely benefits of exercise to the shift worker.

Benefits of Physical Activity to the Shift Worker

Physical activity, when timed appropriately, may consolidate human circadian rhythms. Although purely correlational in nature, there is evidence that good tolerance to rapidly rotating shift work is associated with large amplitudes (mean-to-peak differences) of circadian rhythms, which tend to be observed more in physically active and fitter individuals than in sedentary people. Nevertheless, it may well be that those people who are naturally more tolerant of shift work are able to be more physically active, rather than vice versa. This “chicken or the egg” conundrum is common in many descriptive studies on shift work. There is no direct evidence to suggest that any unique circadian characteristics of physically fit shift workers mediate fewer short-term tolerance problems and better health compared with less fit workers.

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