M5 Throwing / Hitting

Topic

The throwing and striking actions performed by an athlete represent two distinct ballistic modes aimed at maximizing both the speed and the final energy of a projectile—whether it be a ball, a javelin, or a racket—at the precise moment of release or impact.

In contrast, the principle of proximal-to-distal transfer describes how energy progressively accumulates, moving from the athlete's massive, slow proximal segments (such as the hips or trunk) toward the lighter, faster distal segments (such as the hand or the tip of the racket). This creates a whip-like kinetic chain, a mechanism that defines a specific model of energy transfer within this framework.

The conservation of the athlete's final angular momentum is also crucial to the throwing action—a concept that underpins the model regarding rotational movement: the rotation of the hips generates an initial angular momentum that is subsequently transferred to the shoulder, the elbow, and finally the wrist.

Furthermore, the final velocity of the athlete's distal extremity can reach speeds many times greater than that of their center of mass—a key reference point in this model—thanks to the whip-like effect of the kinetic chain mentioned earlier. The more efficiently this kinetic chain transfers energy from proximal to distal segments, the greater the final velocity of the distal extremity becomes. Consequently, this model—which begins by maximizing projectile velocity at the moment of release or impact—dictates that the ball's final velocity following the strike depends on two factors: the coefficient of restitution of the impact (specifically the same coefficient defined by another model in this set) and the mass ratio between the athlete's foot and the ball. In contrast, the final accuracy of the launch depends on the stability of the projectile's release point and its launch angle; this introduces a second, equally necessary condition for the launch, complementing the initial focus on maximizing velocity.

ID:465