Individual differences and segment interactions in throwing *

Arm segment velocities of 12 athletes throwing three differently weighted balk were analyzed by three-mode principal component analysis. Individual differences were characterized in terms of the combined influences of the phases of the throwing motion and the arm segment velocity relationships established in those phases. Using three individual differences components, three velocity measures components and four time phase components, 75% of the variance was described. The arm segment velocity relationships were described by two main components identified as directional velocity and proximal versus distal velocity. The time periods components distinguished between relationships among the m segment velocities that m u r in the windup versus those of the release phase. Three individual differences components are identified and appeared to be related to a general throwing style, the influence of skill level on technique, and the differential effect of the varying ball weights, respectively. Each athlete's throws are weighted combinations of these three components. The timing of segment involvement is investigated and the results indicate sequential patterns from proximal to distal as the throw unfolds. However, the results also suggest that different principles may apply ro different throwers and that the summation of speed principle should not be applied universally to explain segment motion and interaction.