The Biomechanics of the Golf Swing
The golf swing is not hitting at a ball; it is a complex kinetic chain. Power originates in the ground, travels up the legs, through the pelvis, torso, arms, and finally to the clubhead.
Ground Reaction Forces (GRF)
To create rotational velocity, you must interact with the ground. Newton's Third Law applies directly here: to move your body in one direction, you must push the ground in the opposite direction. There are three vectors of force we analyze:
- Vertical Force: Pushing straight down to create lift. This peaks around lead arm parallel in the downswing.
- Horizontal (Shear) Force: Pushing side-to-side. This initiates the weight transfer from trail to lead side.
- Rotational (Torque) Force: Pushing in opposite directions with the lead and trail feet to spin the pelvis.
Center of Mass vs. Center of Pressure
A common misconception is that shifting your weight means moving your upper body laterally (swaying). This moves your Center of Mass (COM).
Efficient players keep their COM relatively centered while shifting their Center of Pressure (COP) laterally. You can press into your right foot without moving your head right.
The 80/20 Rule
By impact, elite ball strikers have approximately 80% to 90% of their pressure on the lead foot. The amateur average is closer to 55%. If you hang back, the low point of the swing arc moves behind the ball.
Kinematic Sequence
Speed is generated by accelerating and decelerating body segments in order: Pelvis → Torso → Lead Arm → Club. If the pelvis doesn't decelerate (post up) on a stable lead leg, the energy never transfers to the torso. The balance board trains the stability required for that deceleration.