Trunk and upper arm postures and movements among older workers in physically demanding occupations

Associations between work-related musculoskeletal disorders (WMSDs) and awkward postures and repetitive movements have been established. Action levels for elevated arms, trunk flexion, and fast movements have been suggested. With today's prolonged working life, older workers in manual jobs may be at increased risk for WMSDs. The aim of this study was therefore to assess postural workload in older workers in four physically demanding occupational groups using technical measurements and compare the exposure of the groups with each other's and with the action level.

Postures and movements were measured for the right upper arm and the trunk using inertial measurement units (IMUs) during 3 workdays in construction workers (n = 35), kitchen workers (n = 37), cleaners (n = 27), and assistant nurses (n = 25), all over 50 years. Angle and angular velocity were computed, and time exceeding suggested angular cut-offs was assessed. Group mean and variance components within and between subjects were estimated in one-way random effect models. One-way ANOVA tests were conducted to compare exposure variables between the occupational groups.

Construction workers spent more time with arms >60° than other occupational groups (7.9% vs. 4.4-5.6%) and >90° (2.8% vs. 1.0-1.3%). Across groups, a substantial share of days exceeded suggested action level for arm elevation >30° (8.0-24.6%) and >60° (6.3-22.7%). Cleaners had the highest 50th percentile trunk flexion (15.3°), while construction workers spent the most time with trunk flexion >45° (12.6%) and >60° (7.4%); exceedances of recommended levels occurred in up to 39% of days. Kitchen workers and cleaners exhibited more time with fast arm movements (31.8-35.6% vs. 23.9-24.0%). Considerable variability was observed both within and between individuals.

In the included occupational groups, in workers over 50 years, arm elevation and trunk flexion may often exceed recommended levels. Since the physical capacity is decreasing with age, this indicates elevated musculoskeletal risks, and there is a clear need for targeted ergonomic measures to support sustainable working lives.