Frame #X -- The Follow-Through
Rotation is complete and the ball has left the bat. All bat speed generating energies have been depleted. The muscles have entered a more relaxed mode. The lead-arm is casting away from chest as the back-arm extends past the "L" position. It is the now the momentum of the bat that powers the limbs and body into the follow-through phase.
Heavy Bag Drill & Deflated Balls
To Jack from Lau -- Firm Front Leg