Effects of posture on dynamic back loading during a cable lifting task

Abstract

This study evaluated spinal loads associated with lifting and hanging heavy mining cable in a variety of postures. This electrical cable can weigh up to 10 kg per metre and is often lifted in restricted spaces in underground coal mines. Seven male subjects performed eight cable lifting and hanging tasks, while trunk kinematic data and trunk muscle electromyograms (EMGs) were obtained. The eight tasks were combinations of four postures (standing, stooping, kneeling on one knee, or kneeling on both knees) and two levels of cable load (0 N or 100 N load added to the existing cable weight). An EMG-assisted model was used to calculate forces and moments acting on the lumbar spine. A two-way split-plot ANOVA showed that increased load (p < 0.05) and changes in lifting posture (p < 0.05) independently affected trunk muscle recruitment and spinal loading. The increase in cable load resulted in higher EMG activity of all trunk muscles and increased axial and lateral bending moments on the spine (p < 0.05). Changes in posture caused more selective adjustments in muscle recruitment and affected the sagittal plane moment (p < 0.05). Despite the more selective nature of trunk EMG changes due to posture, the magnitude of changes in spinal loading was often quite dramatic. However, average compression values exceeded 3400 N for all cable lifting tasks.

Effects of occupational heat exposure on female brick workers in West Bengal, India

“…Many authors have used HR rest as an indicator of physical workload related to muscular activities (38, 39). As the muscular activities are constant, so an increase in temperature in the summer months probably increases the HR rest and thus the overall workload of these female workers.…”

Spinal loading during manual materials handling in a kneeling posture

“…Alterations in muscle recruitment patterns were reported by Gallagher et al [10,11], who demonstrated that posture specific selective muscle recruitment occurs, independent of the load lifted, as individuals shift between standing, stooping, and kneeling on one or two knees. Squatting has been shown to reduce the activity of the lumbar erector spinae when compared to kneeling for a baggage handling task, while kneeling resulted in lower activity in the trapezius [46].…”

Physical limitations and musculoskeletal complaints associated with work in unusual or restricted postures: A literature review

“…A recent study examined the influence of posture and load on the electromyographic activity of 10 trunk muscles during a heavy cable-lifting task (Gallagher, Marras, Davis, & Kovacs, 2002). Results of this study indicated that posture and load have quite different influences on trunk muscle recruitment (and thus loads experienced by the lumbar spine).…”