Follow-through Phase

Deceleration and Finish Stages:

Although not directly related to force production, the follow-through phase ensures the stabilisation and injury management of the player. During deceleration, the force between the players trunk and arm can exceed 300 N.m (Kovacs & Ellenbecker, 2011). As such, rotator cuff injuries are likely to occur due to tensile failure, as the muscles contract to resist the force (Martin, Bideau, Ropars, Delamarche & Kulpa, 2014).

Resultantly, the law of conservation of momentum is crucial to minimise injury during deceleration (Blazevich, 2017). As presented in Figure 11, the law of conservation of momentum causes Roger Federer to follow through with the anterior movement of his arms, trunk and subsequent COM, until a break force is applied (Blazevich, 2017). Likewise, his ipsilateral foot flicks backwards and up, increasing his MOI by increasing the radius of gyration. Thus, per the equation for angular momentum (H=Iω), increasing his MOI (I) shall decrease the angular velocity of the body, whilst momentum is conserved (Blazevich, 2017). Consequently, following through with the serve whilst increasing one’s inertia, aids deceleration. Furthermore, this action keeps the player’s COM within their BOS, aiding stability and reaction to serve return.

As the player falls from their acceleration phase, their PE is converted to KE, increasing their downwards velocity (Blazevich, 2017). The player places the ball of their foot on the ground first, applying a breaking force which stabilises them, per Newton’s Third Law (Blazevich, 2017). This causes hyperextension of the knee; therefore, the player’s knee bends to increase the duration of the impulse, I=F.t (Blazevich, 2017). Thus, the force of impact is dispersed over a greater duration.