Abstract

The purposes of this study were to create a mathematical model of the human upper extremity and to apply the model to the acceleration phase of the fast baseball pitching motion. Angular trajectories at the elbow and wrist joints in the fast baseball pitching were generated experimentally by a three-dimensional cinematographic technique and theoretically by simulation technique. The mathematical model was applied to generate angular trajectories that closely matched the experimental trajectories at the elbow and wrist joint and the maximal angular trajectories at the elbow and wrist joint in the pitching motion. Under the conditions that the tracking parameters, initial and final angles, and performance time were predetermined, this author was unable to obtain dramatic changes in the angular trajectory of the elbow joint toward an angular trajectory that resulted in increased hand velocity at the ball while the angular trajectory at the joint quite differed from the experimental angular trajectory. The hand velocity at the ball release was not very increased from the velocity obtained from the experiment. The trajectories of the pitching arm depend heavily on the motion of the other body parts connected to the upper arm through the shoulder joint. Therefore, the maximal angular trajectory of the pictching arm that can be obtained from simulation is not the true maximal angular trajectory unless the motion of the other body parts is maximal. Verf.-Referat