The effect of gender and training experience on body segments’ contribution in overarm throwing

Fast explosive movements of the extremities seem to occur in a proximal-distal (P-D) sequence of motion of body segments. The P-D sequence is thought to maximize outcome performance. This sequence has been unmistakably identified for explosive lower limb actions as in vertical jumping, sprinting, and kicking. However, experimental data on overarm throwing are not always consistent in this respect. Whereas some authors have identified a proximal to distal sequence, some have reported that the proximal-to-distal sequence does not occur as indicated by maximal linear velocities of the shoulder, elbow and wrist. Moreover, little information is available on the most proximal body segments. This poses doubt on the general validity of the proximal-distal sequence theorem. Whereas the proximal-distal sequence seems to be a fully natural phenomenon in extension of the lower extremity this is apparently not that clear for overarm throwing In the present paper we aimed at studying the contribution of the various body segments in handball overarm throwing, particularly the trunk and lower extremity, and the sequential timing aspect as such. We argue that no gender differences should be expected in the relative contributions of the body segments as there are no obvious reasons to suggest that the P-D sequence or contribution per se is gender specific. On the other hand, any differences between trained and untrained subjects would indicate that the proximal-distal contributions are (partly) learned or at least optimized through experience. Kinematical 3D recordings of 19 trained (10 males / 9 females) and 20 untrained (10 males / 10 females) subjects were recorded by a 10-camera, 500 Hz ProReflex system. Segmental contributions were calculated as the difference in linear velocity between a proximal and distal joint of the relevant segment. We considered the P-D sequence in an integrated manner, that is, we compared the segments’ contributions during the last 200ms and 100ms of the throw. The presence of this sequence would yield a relative increase in the distal segments and a relative decrease in the proximal segments from the first to last time period. The main findings of the current study are: Men and women show no difference in contribution of the various segments in handball overarm throwing, except for the lower extremity and trunk during the 200ms period before ball release; Trained subjects show a greater contribution than untrained in the lower extremity (anti-goal directed movement) and the hand movement. When considering the proximal-distal sequence, a sequence between arm and hand was identified that was more elucidated in men than in women, and to minor extent more in trained than in untrained subjects. Apparently, the proximal-distal sequence is a natural aspect of anyone's throwing technique, but the amount of contribution of the hand movement seems to be an acquired skill.