Development of a muscle strength evaluation system for five muscles classified by function of knee and ankle joints

Estimation/evaluation of muscle strength of limbs are needed as an evaluation index for clinical practice and sports training. The evaluation method of muscle strength using functionally effective muscule theory uses a two-dimensional musculoskeletal model of three pairs six muscles, in which the limb muscles are classified according to their functions, and enables the evaluation of muscle strength for each muscle group. In this study, we developed a new system to evaluate the muscle strength of each muscle group in a five muscle model that separates the bi-articular muscle strength of knee and ankle joint using the functionally effective muscular theory. The developed system consists of a device for measuring foot tip force in real time and a calculation algorithm for evaluating the muscle strength of five muscles from the measured data. The former one is a device that measures the foot tip force exerted at the foot by a force sensor attached to the boot. The latter one calculates the position of the exerted force in the boot from the foot tip force, and derives the muscle group torques of the five muscles, taking into account the variation of the exerted force position. In this paper, we show the validity of the developed system by comparing the results from Cybex measurements.