Objectives The relationship between a combination of demanding work-schedule characteristics and reported musculoskeletal disorders of the neck, shoulders, and back was examined.

Methods A probability sample of 1163 nurses, randomly selected from the list of actively licensed nurses in two states of the United States, served as the sample for this cross-sectional study. Data were collected via an anonymous survey mailed to the participants` homes from October 1999 through February 2000.

Results Four of the nine work-schedule characteristics (working full-time, >8 hours/day, 2-4 weekends/month, and other than day shift) were significantly related to musculoskeletal disorders in one or more body sites. When a work-schedule index was created by summing the nine characteristics, a demanding schedule was significantly associated with musculoskeletal disorders in the neck [odds ratio (OR) 1.10, 95% confidence interval (95% CI 1.00-1.21], shoulder (OR 1.12, 95% CI 1.01-1.23), and back (OR 1.16, 95% CI 1.06-1.27). Adjustment for psychological and physical job demands reduced the odds ratios slightly and therefore suggested that some of the association between musculoskeletal disorders and schedule was due to increased exposure to these job demands. Working "long hours" (>12 hours/day, >40 hours/week) and "off hours" (weekends and nondayshifts) were associated with a 50-170% increase in the age-adjusted odds ratio for musculoskeletal disorders in the three body sites.

Conclusions The findings of this study suggest that preventing musculoskeletal disorders requires system-level approaches to scheduling that reduce the time of exposure to demanding work conditions and promote healthful work-rest patterns.

Key terms back problems; long workhours; MSD; musculoskeletal disorder; neck problem; registered nurse; shift work; shoulder problem; work-schedule characteristics