A15 テニスサーブ動作におけるラケット速度生成に対する上肢筋張力の貢献(打撃動作)

Abstract

The purpose of this study was to estimate the contributions of the upper limb muscle forces to the generation of racket speed during tennis serve motion. The upper body segments and racket were modeled as a system of 11-rigid linked segments. The sternoclavicular, elbow and wrist joints except the shoulder joint were modeled by a two-axial revolute joint to consider the constraint degree of freedom (DOF) of these joints, and the hand was considered to be connected with the racket via zero DOF virtual joint. Motion dependent term, which shows large contribution in swing motion, was converted into other terms by using the equation of motion expressed in the discrete time system. A recurrent equation with respect to the generalized velocity vector of the system is derived to calculate the contribution of the joint torque terms, external joint force term, and gravity term to the motion dependent term. Then we developed a method to estimate the contribution of the upper limb muscle forces by using the musculoskeletal model consisting of 45 Hill-type muscles with use of SIMM software (MusculoGraphics Inc.). One male tennis player's motion was captured by VICON 612 system (9-cameras, 250Hz). The results obtained in this study shows that muscles in the upper arm, such as biceps brachii and brachialis and deltoid muscles, make significant role in the generation of the racket speed during forward swing motion in tennis serve.