Sudden loading during manual material handling poses a significant risk of back injury. The present study investigated the effect of load holding height on trunk biomechanics (trunk flexion angle and L5/S1 joint compression force) during sudden loading. Eleven subjects were recruited to perform sudden loading tasks with a 6.8 kg load, while maintaining upright standing posture and holding load at three different height levels in the sagittal plane. It has been found that load holding height significantly affected L5/S1 joint compression force and trunk flexion angle. With a lower load holding height, peak L5/S1 joint compression force decreased by 17.5%. According to these findings, it is suggested that holding load at a lower level could help reduce the risk of low back injury.
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