Biomechanical analysis of risk factors for work-related musculoskeletal disorders during repetitive lifting task in construction workers

Work-related musculoskeletal disorders (WMSDs) represent major health issues for construction workers yet risk factors associated with repetitive lifting tasks remain unexplored. This study evaluates the effects of lifting weights and postures on spinal biomechanics (i.e. muscle activity and muscle fatigue) during a simulated repetitive lifting task undertaken within a strictly controlled laboratory experimental environment. Twenty healthy male participants performed simulated repetitive lifting tasks with three different lifting weights using either a stoop (n = 10) or a squat (n = 10) lifting posture until subjective fatigue (a point in time at which the participant cannot continue lifting further). Spinal biomechanics during repetitive lifting tasks were measured by surface electromyography (sEMG). Results revealed that (1) increased lifting weights significantly increased sEMG activity and muscle fatigue of the biceps brachii (BB), brachioradialis (BR), lumbar erector spinae (LES), and medial gastrocnemius (MG) muscles but not the rectus femoris (RF) muscle; (2) sEMG activity and muscle fatigue rate of the LES muscle were higher than all other muscles; (3) a significant difference of sEMG activity of the RF and MG muscles was observed between lifting postures, however no significant difference of muscle fatigue was apparent (p > 0.05). These findings suggest that risk factors such as lifting weights, repetitions and lifting postures may alleviate the risk of developing WMSDs. However, future research is required to investigate the effectiveness of using ergonomic interventions (such as using team lifting and adjustable lift equipment) in reducing WMSDs risks in construction workers. This work represents the first laboratory-based simulated testing conducted to investigate work-related musculoskeletal disorders (WMSDs) primarily caused by repetitive lifting tasks and manual handling. Cumulatively, the results and ensuing discussion offer insight into how these risks can be measured and mitigated.