Discus throwing performances and medical classification of wheelchair athletes

Purpose: The purpose of this study was to identify those kinematic characteristics that are most closely related to the medical classification and measured distance of a throw. Methods: Two S-VHS camcorders (60 fields.s(-1)) were used to record the performance of 14 males of different classes. Each subject performed 10 trials and the best two trials from each subject were selected for analysis. Three-dimensional kinematics of the discus and upper body segments at the instant of release and the range of motion and average angular speed of different segments during the final forward swing were determined. Results: The speeds of the discus at release, ranging from 9.9 to 17.2 m.s(-1), were smaller than those exhibited by elite male able-bodied throwers. However, the angles of release, ranging from 24.6 to 41.4 degrees, were comparable with those observed in able-bodied throwers. Of the segmental kinematic parameters, (a) the inclination and angular speed of the upper arm at release; (b) the ranges of motion of the shoulder girdle, upper arm, and forearm during the forward swing; and (c) the average angular speed of the shoulder girdle during the forward swing were significantly correlated to both the classification and measured distance. The inclinations of different segments at the instant of release suggested that athletes with high level of spinal cord injury emphasized the elbow flexion to compensate for the deficiency in shoulder girdle movement. Conclusions: In addition to the speed of the discus at release, the shoulder girdle movement during the forward swing is an important determinant of classification and measured distance.