Ground Reaction Force
Ground reaction force is the push the ground gives back to a golfer’s body during the swing. When the feet press down into the turf, the ground presses back with equal strength in the opposite direction, and golfers use that returning force to build clubhead speed.
What is a ground reaction force?
The term comes straight from physics. Newton’s third law says that for every action there is an equal and opposite reaction, so when a golfer pushes down and sideways into the ground, the ground pushes back by the same amount. That returning push is the ground reaction force, often shortened to GRF.
Every golfer produces it on every shot, whether they think about it or not. Coaching resources on force-plate technology make the point that the force is always present as long as a player stays in contact with the surface. It only becomes useless when the surface cannot push back, which is why swinging on a sheet of ice, or on loose sand, feels so powerless.
What matters for golf is how the player uses that returning force. It travels from the feet up through the legs, hips, torso, arms, and finally the club, a linked sequence coaches call the kinetic chain. A golfer who presses into the ground at the right moment feeds energy into that chain. A golfer who stays flat-footed and passive gives the chain little to work with and ends up swinging mostly with the arms.
The three types of ground reaction force in golf
Force plates, the pressure-sensitive plates a golfer stands on during a swing analysis, break GRF into three directions. Each one does a different job in the swing.
Vertical force
Vertical force is the up-and-down push, the same motion as a jump. A golfer loads into the ground and then pushes back against it, and the ground drives back upward. Research summarised by golf biomechanist Kiran Kanwar puts the peak vertical force for a driver at roughly 1.6 times body weight, drawing on work by Dillman and Lange. With the game’s biggest hitters, the vertical push is so strong that the lead foot can leave the ground entirely near impact. Justin Thomas and Lexi Thompson are two players whose feet visibly come off the turf on full swings.
Horizontal force
Horizontal force, sometimes called shear or lateral force, runs side to side and toward or away from the target. It lets a golfer push one way to move the body the other way. For a right-handed player, pressing toward the trail side early in the downswing helps shift the body mass toward the target. This horizontal push grows as vertical force grows, because a harder downward press gives the feet more grip on the ground to work against.
Rotational force
Rotational force, or torque, is what turns the body. When the two feet push in opposite directions at the same time, they create a twisting effect called a force couple. A 1994 study by Barrentine, Fleisig and Johnson found that across all skill levels, about two-tenths of a second after the top of the backswing, the trail foot pushes backward while the lead foot pushes forward. With the shoes locked into the ground, that pair of opposing pushes rotates the body toward the target.
How ground reaction force creates clubhead speed
Speed at the clubhead starts at the feet. The force a golfer generates against the ground is the raw material the body has to work with, and it moves up the kinetic chain segment by segment until it reaches the ball at impact.
The link between using the ground well and swinging fast is not just a coaching theory. A 2026 systematic review in Sports Medicine looked at 24 studies on GRF and centre of pressure in the golf swing. Ten of them found moderate-to-strong relationships between force use and clubhead speed, and more skilled golfers tended to produce higher forces and faster clubhead speeds than less skilled players.
Timing matters as much as size. The best players apply their three forces in a repeatable order rather than all at once, and that sequence looks strikingly alike from one elite golfer to the next. A player can generate plenty of force and still waste it by delivering it in the wrong order or at the wrong moment.
How ground reaction force is measured
GRF cannot be seen with the naked eye, and ordinary swing video will not capture it. Coaches measure it with force plates, which read the push a golfer applies in all three directions many times a second.
The Golf Teaching and Research Center at Penn State describes how the reading is displayed: arrows show the force under each foot, and a combined arrow shows the total. The taller the arrow, the greater the vertical force; the more it tilts, the greater the horizontal force. During most of the swing, the vertical component is far larger than the horizontal one.
Force plates also track the centre of pressure, the single point where a golfer’s pressure is concentrated at any instant. Watching that point travel from foot to foot through the swing tells a coach how a player is loading and shifting, information a pressure mat or a camera alone cannot supply.
Ground reaction force vs. pressure
Because both come from force plates, ground reaction force and pressure often get mixed up, but they answer different questions.
Ground reaction force is a true force. It has a size and a direction, and a force plate reads it in all three dimensions at once. Pressure is different: it describes how a golfer’s weight is split between the feet at a given moment, usually shown as a percentage on each foot. Pressure tells you where the load sits. Ground reaction force tells you how hard, and in which direction, the player is pushing.
| Metric | What it shows | How it reads |
|---|---|---|
| Ground reaction force | Size and direction of the push against the ground | Newtons or multiples of body weight, in three directions |
| Pressure | How weight is split between the feet | Percentage on each foot |
| Centre of pressure | The single point where pressure concentrates | A moving location that travels between the feet |
A simple way to hold the difference: pressure is about location, while ground reaction force is about force and direction.
Related Golf Terms
- Swing path — The direction the clubhead travels through impact.
- Posture — The body angles a golfer sets at address.
- Low point — The bottom of the swing arc, ideally just ahead of the ball with irons.
- Width — Maintaining arm extension to create a wide, powerful swing arc.
- Spine angle — The forward tilt of the spine maintained throughout the swing.
Frequently Asked Questions
Do amateur golfers use ground reaction force?
Yes. Every golfer in contact with the ground produces it on every swing. The difference is that skilled players tend to apply more force, and apply it in a better sequence, than beginners.
Is ground reaction force the same as weight shift?
No. Weight shift is the movement of the body’s mass from one foot to the other. Ground reaction force is the push against the ground that drives and controls that movement, so weight shift is one visible result of using GRF.
How much vertical force do golfers produce?
Studies referenced by biomechanist Kiran Kanwar put peak vertical force for a driver at about 1.6 times body weight, and some long hitters generate well above their own body weight, enough that the lead foot lifts off the ground.
Can you feel ground reaction force in your own swing?
Somewhat. A golfer can feel pressure move between the feet and can feel the legs pushing into the ground, but the precise size and direction of the force can only be measured on a force plate.
Sources
- Swing Catalyst. “Ground reaction force.” Accessed July 2026.
https://swingcatalyst.com/resources/articles/ground-reaction-force - Golf Teaching and Research Center, Penn State. “Ground Reaction Forces.” Accessed July 2026.
https://golf.psu.edu/biomechanics-of-golf/biomechanical-assessment-of-3d-data/ground-reaction-forces - “Ground Reaction Force and Centre of Pressure During the Golf Swing and Associations with Clubhead Speed and Skill Level: A Systematic Review.” Sports Medicine, 2026.
https://link.springer.com/article/10.1007/s40279-025-02391-3 - Kanwar, K. “The Ground Realities of Ground Reaction Force.” Citing Barrentine, Fleisig & Johnson (1994) and Dillman & Lange (1994). Accessed July 2026.
http://www.golfbytourmiss.com/2016/03/the-ground-realities-of-ground-reaction-force-special-report-by-kiran-kanwar/ - Blackburn, M., via golf.com. “What are ground reaction forces and how do they affect your swing.” Accessed July 2026.
https://golf.com/instruction/home-practice-mass-pressure/
