Effect of body postures on gripping force classification using a multimodal system of electromyography and handgrip strength measurement

Abstract

Musculoskeletal disorders are injuries due to fatigue and weakness in muscle strength from activities that involve prolonged static posture such as sitting and standing postures. Handgrip strength measurement is a popular method that has been used in rehabilitation for the recovery of muscle strength of the upper limb. There are also previous studies that utilized electromyography for hand function assessment. Several studies have been conducted to investigate the relationship between static posture and handgrip strength, however, only a few electromyography studies examined the effects of sitting and standing on the muscle activities during hand gripping movement. The research aims to compare electromyography signals during sitting and standing postures while performing handgrip activity and to identify the postures that have a higher risk of musculoskeletal injuries. The comparison between handgrip strength and electromyography signals showed that both methods can detect the effect of posture on handgrip activity, even if the feedback values are small. The results show that the grip strength value during the sitting position is significantly higher than the grip strength value during standing. Meanwhile, the feature extraction namely, root mean square produces values of electromyography related to the posture and force. The result showed that the electromyography amplitude is higher for sitting posture than for standing position which is different from handgrip measurement. This is due to the muscular load in the sitting posture being higher than the standing posture. In conclusion, the sitting and standing postures have a significant effect on both handgrip strength and electromyography measurements when performing upper limb studies.