Evaluation of Muscle Strength Measurement System for Five Knee and Ankle Joint Muscles in Young Adult Males

Measurement of bi-articular muscle strength related to human limb motor control is required for clinical practice and sports training evaluation. The muscle strength measurement method that utilizes functionally different effective muscle theory employs a two-dimensional musculoskeletal model of six muscles for two joints, wherein limb muscles are classified according to their functions and used to measure the muscle strength for each muscle group. In this study, we evaluate the muscle strength measurement system (MSMS) of each muscle group in a five-muscle model including a bi-articular muscle of the knee-ankle joints in ten young adult males. Instructions are provided to participants, and measurements are conducted while checking the results displayed on the monitor. The knee extension torque of MSMS was comparable to that of the conventional joint torque measurement systems. In addition, we propose two new methods for drawing output force distributions (OFD). Five muscle group torques obtained by the two methods are evaluated by the physiological cross-sectional area of the ankle plantar flexors. Reconsidering the measurement instructions given to participants for the two sides of the OFD related to the bi-articular muscle and the OFD drawing methods is necessary.