Evaluation of a competition wheelchair based on estimation of muscle activity for straight-ahead operation by using inverse dynamics analysis

Abstract

The objective of this study was to evaluate an optimum structure for a rugby wheelchair by estimating the muscle force during straight-ahead operation of the wheelchair using a musculoskeletal simulation analysis. The simulation model was represented by restraining the contact area between the frame and seat of wheelchair and the body model. Muscle force during operation was estimated by an inverse dynamics analysis. In this study, three kinds of body model were constructed with different degree of disability, targeting the most player numbers class 2.0, which was set from the sum of scores based on degrees of the disability of upper limbs and trunks. Wheelchair models were also constructed by varying the range of camber angle (4-grade, 2°intervals), wheel diameter (3-grade, 25mm intervals) and axle positions (5-grade, 50mm intervals up/down and fore/rear), respectively. Effects of design parameters for the wheelchair on the muscle force were investigated, and the combination of parameters able to decrease the muscle force was identified. As a result, the axle position has the strongest effect on muscle force of upper limbs, and it is effective to lower the axle position for reducing the muscle force. This represents that the adjustment of axle position leads to a reduction in risk of injury occurrence.