Ground Reaction Forces (GRF)
You can only swing as fast as your connection to the ground permits. Understand the forces that dictate power.
Newton's Third Law states that for every action, there is an equal and opposite reaction. In golf, the only way to generate immense clubhead speed is to push against the Earth, so the Earth pushes back.
The Three Dimensions of Force
Using dual 3D force plates, biomechanists have categorized golf GRF into three distinct directions:
1. Horizontal (Shear) Force
The side-to-side force. This moves your Center of Mass (COM) away from the target in the backswing, and toward the target in transition. It is the first force to peak in the downswing.
2. Torsional (Rotational) Torque
The twisting force applied through the feet, acting like a steering wheel. Your lead foot pushes forward and out, while your trail foot pulls back, spinning the pelvis. This peaks second.
3. Vertical Force
The upward push against the ground (jumping). This is the largest magnitude force, often exceeding 200% of body weight in elite players. It peaks last, typically when the lead arm is parallel to the ground in the downswing.
Timing is Everything
Generating 200% bodyweight vertical force is useless if it happens at impact. By the time the club strikes the ball, vertical force has almost returned to zero. The push must happen early in the downswing to brake the pelvis and snap the Kinematic Sequence.
Curious about your potential? Estimate your peak forces using our GRF Estimator Tool.