Long-term assessment of upper arm posture and motion and their association with discomfort perceived symptoms among bakery workers

Background: The highest prevalence of work-related musculoskeletal disorders (MSDs) among bakery workers is reported in the shoulder region. Awkward shoulder postures have been suggested to be a cause of shoulder discomfort in bakery workers. This study aimed at long-term assessment of upper arm posture and motion and their association with discomfort perceived symptoms among bakery workers. The results of this study are expected to have an effective role in identifying risk factors in order to provide appropriate strategies for preventing shoulder disorders in bakery workers. Methods In this study, fifty seven bakers of the three types of bread baking systems (sangak, taftoon and tanoori baking systems), were randomly selected. The self-reported severity and frequency of shoulder discomfort perceived by workers were recorded. Working postures and movements of the shoulders during work were continuously recorded with inclinometry measurements during three hours. Results Results suggest bakery workers, especially sangak bakers, may be exposed to high physical exposure levels. A significant correlation were found between perceived discomfort intensity on VAS scales for the right and left shoulder angles (50th) among bakers in sangak baking system (p≤0.005). Percentage of time spent with the upper arm right elevated more than 60° was significantly correlated with perception of shoulder discomfort for all bakery workers (p≤0.05). Angular velocity was significantly negatively correlated with perceived discomfort intensity for both upper arms (p≤0.005). Conclusions Study findings suggest, in addition to high physical exposure level, poor workstation design and inappropriate hand tools may be the main risk factors for developing disorders in the shoulder regions among bakers. Our results can provide more informed decisions with respect to both engineering (e.g. ergonomic workstation and equipment design) and administrative (e.g. work organization) control strategies.