A kinematic analysis of an upper extremity ballistic skill: the windmill pitch.

The purposes of this study were (1) to determine the relative motions of the upper limb segments during the execution of the softball windmill pitch (2) to attempt to determine the effect of these motions on the performance of the skill. High speed motion picture film was used to calculate the kinematic parameters of the pitching arm segments during the pitch. Four highly-skilled pitchers were used as subjects. Each performed at least ten trials of the pitch, which were recorded by two motion picture cameras. The two trials with the fastest ball velocity for each of the four subjects were analyzed from a sagittal aspect only. The resulting kinematic analysis indicated that there was a definite proximal-to-distal sequence of these motions, with decelerations occurring in the proximal segments prior to release of the ball. It was concluded that one of the critical factors in highly-skilled performance of ballistic skills is the ability to decelerate such segments, which likely require very strong eccentric contractions of antagonistic muscle groups.