Workers’ subjective discomfort, muscle fatigue, and kinematics during a manual packaging task

Abstract

BACKGROUND: Due to the prevalence and increased demand for manual packaging tasks, the concern for worker health and safety has grown. OBJECTIVE: This study aims to assess the effects of gender and work postures on subjective discomfort, muscle fatigue, and kinematics during a manual packaging task. METHODS: Twenty participants, including 10 males and 10 females, were recruited to perform a 60-minute manual packaging task in sitting and standing postures. RESULTS: Discomfort was evidenced by increased the rating of perceived exertion (RPE) values (sit: from 6 to 14.55; stand: from 6 to 17.15) and muscle fatigue was supported by decreased median power frequency (MPF) values for right brachioradialis (RB) (sit: –23.68% ; stand: –16.20%), right upper trapezius (RUT) (sit: –20.14% ; stand: 11.79%), and right erector spinae (RES) (sit: 8.64% ; stand: 11.21%) muscles. Women were more likely to bend forward in a relaxed upper body position, especially while sitting, which may increase the risk of low back pain and women also reported greater discomfort than men, but not in the hands and back. Compared with sitting, the back showed greater muscle fatigue in standing, while muscle fatigue for the shoulders and hands was the opposite. CONCLUSION: These findings suggest that work posture should be considered to prevent fatigue in manual packaging tasks. Given the impact of gender on muscle fatigue, work performed by women and men should both be considered. The results can help to develop action strategies and work posture design to prevent musculoskeletal disorders in the manual packaging industry.