Proposed Drawing Method for Output Force Distribution and Muscle Strength Evaluation Method of Limbs Based on Cosine Tuning

Abstract

The theory of functionally different effective muscles allows for detailed measurement of the muscle strength of limbs by separating mono-articular and bi-articular muscles. The theory represents the output force distribution (OFD) at the end of a limb as a hexagon whose opposite sides are parallel and of the same length. The measured OFD is used to derive the muscle strength under an assumption. The muscle strength is affected by the assumption and all sides of OFD. This paper proposes a new method for obtaining the muscle strength from corresponding sides of the OFD without the assumption. The method is based on minimizing the sum of the square of the muscle strength induced by the central nervous system which is called cosine tuning. The slope of each side of the OFD is formulated from the limb posture, which is applied to the measurement of the OFD. The muscle strength is independently derived from the corresponding side only. The proposed and conventional methods were applied to three subjects, and the result of the OFD and the muscle strength were presented.