Pushing tasks: impact of handle design on trunk muscles

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University of New Brunswick


Industrial cart handle design can vary an individual’s push capacity up to 9.5% and can impact the function of trunk muscles. However, to date no studies have examined the neuromuscular activity of the trunk muscles involved using surface electromyography (sEMG). The purpose of this study was to examine the effects of handle design on trunk muscle activity and handle push force when initiating the push of a platform truck. Ten male and ten female participants (mean age = 24.25 ± 4.28 years) pushed 216 kg using six different handle designs. Multichannel high density sEMG (HDsEMG) data were recorded from three trunk muscles (rectus abdominis, erector spinae and external obliques) while a force transducer collected hand force. Spatial distribution was estimated using the Root Mean Square (RMS) and 2-Dimensional (2D) maps were developed to examine spatial features including differential intensity and intensity. Coefficient of variation (CV) and entropy was also used to examine alterations in muscle heterogeneity and pattern. The handle design involving a hip height and horizontal handle orientation (HH) resulted in significantly greater entropy (p=0.023) which demonstrated homogeneity among the trunk muscles, significantly lower mean RMS (p<0.05) and significantly lower hand force (p<0.05). The current research suggests that the HH handle design reduces trunk muscle activity while maximizing the hand force initiating the push, which may help determine optimal work protocols and improve current handle design.