Using Ground Reaction Force for Power

“In physics and biomechanics, the ground reaction force (GRF) is the force exerted by the ground on a body in contact with it.”

Imagine hitting a tee shot while suspended in air. How far do you think the ball would travel? Right, not very. Your power comes from exerting force on the ground and, as Newton’s 3rd law says, having the ground exert its force on you.

During the critical transition phase of the swing, the average 180 lb. pro exerts about 148% of his body weight. That comes to 266, lbs. of force. World Long Drive Champion Ryan Winther, at 220 lbs., exerts 250% of his body weight, equaling 554 lbs. of force. That’s why Ryan can routinely drive the ball well over 500 yards. How about the amateur?

Well, the average amateur exerts a mere 65% of body weight. So a 180 pound amateur can only muster up 117 lbs. of force. Interestingly, that’s less force than at the start of his take-away. So does the problem lie in technique or fitness. Not surprising, both. We’ll start with technique.

The Fix: Technique

First and foremost is the “awareness” that you must “push” off the ground. Second, is identifying the source of the “power leaks.” David Ledbetter has some excellent comments and drills, which we’ll reproduce in its entirety

The Fix: Fitness

Here, you’ll train for power, not strength (see Fitness Training). The idea is that you’re not pushing “slowly and steadily” off the ground throughout the swing. In the take-away you’re building up and “storing” the force on your right side. Then in the transition, a percentage of the force shifts on to your left side (leg). It is at that precise moment that you push off the ground with an instantaneous explosive burst. Think of the Big Bang. The success of this explosion lies in the ability of your legs to generate power, not strength. Remember power is strength condensed to an instant. As you’ll see in the Power Zone, the exercises are all designed for you to develop rapid-fire muscle contraction where all your neurons are firing at their max!

1. THE START OF THE BACKSWING

Ground force:

Pro: 125% of body weight

Amateur: 70% of body weight

Most amateurs tend to lose leverage early in the backswing by raising their bodies, which lightens the force they apply to the ground. The pros do the opposite and apply even more force, giving them a much more stable base to coil the upper body.

DRILL

Take a wood block or similarly weighted object such as a hardcover book and place it behind your 6-iron at address. Push the block away from the target as you start your backswing (right. You should feel pressure building in your right heel as well as the ball of your left foot from the extra effort it takes to move the block.

2. HALFWAY BACK

Ground force:

Pro: 125% of body weight

Amateur: 65% of body weight

Even if they had good ground force at the start of the swing, many amateurs lose that grounded feeling at this point. As that pressure decreases, they stop coiling and begin to lift their hands and arms as a compensatory move to finish the backswing. Pros continue to coil all the way to the top because they’re still grounded.

DRILL

Place a club on the ground and stand on the shaft with both feet as shown (right, shoes optional). Then swing a 6-iron while standing on the shaft. As you move past the halfway point in your backswing, you should feel a steady or increasing amount of force in your right heel and the middle of your left foot. Because of this force, you should be able to complete your upper-body turn just like the pros do.

3. THE TRANSITION

Ground force:

Pro: 145% of body weight

Amateur: 90% of body weight

As the club starts down, elite players increase the pressure under their feet — it looks as if they’re starting to squat — which shallows the swing plane and increases clubhead lag. It’s a huge power move. Most amateurs swing down on too steep of a plane and release the clubhead lag early, usually resulting in a weak slice. They often have more ground-force pressure halfway down than at impact. The sequence of the downswing should be from the ground up, but these players frequently do just the opposite, leading with the upper body.

DRILL

Set up with your feet and hips open to the target and take the club to the top. As you start to swing down (right), rotate your hips in a clockwise direction — a feeling of closing them off to your target even more. This dynamic move will force you to push into the ground with your front leg. It also will keep your shoulders from unwinding early and will drop your arms and club onto a shallow plane. Those are keys to hitting a powerful shot that curves from right to left.