Forces, Center of Pressure & Center of Mass in the Golf Swing
We change the amount of force we apply and the direction we apply it to not only move our bodies, but also to create rotational speed. The amount of force, the direction it is applied, and where it is applied all impact the quality of the swing. It is very important for the center of pressure to not be under the center of mass for most of the golf swing. The center of pressure should move to the trail side in early and mid-backswing, and then move substantially and rapidly to the lead side during the early downswing. The center of mass, however, should not move as much from side to side, and if it does, the golfer will have a very difficult time developing club speed.
The following video shows ground reaction forces in two swings.
We will now take a look at two examples of ground reaction forces during the golf swing.
First, we'll show you the swing at nearly full speed, then slow it down. And now we'll go through the phases of the swing. At the beginning of the golf swing we want to load the trail side, so we want an increase in the right foot force in this golfer, which will shift the center of pressure to his right. You'll notice that his center of pressure moves farther right than his center of mass. And then, as we're nearing the top of the backswing, we're going to see more of a horizontal push. The golfer is getting ready to push himself toward the target, so you can see the combined ground reaction forces now tilting substantially toward the target. So a quick, big sideways push that starts the body moving toward the target, but we don't want to move too far, so we tilt the combined force arrow back away from the target. At this point, we're trying to have a large vertical force out on the left lead side. So again, from the top, we push sideways, push hard with the left, and then you'll see the right and left foot forces start to even out as we go to finish.
We'll now show you an example of a golfer with a very aggressive ground reaction force pattern. Playing slowly the swing looks about the same at the beginning. There is a shift in increase in the right foot force as the golfer loads that side in the early and mid backswing. Then, in the late backswing, this golfer shows a substantial unweighting as the vertical force drops on both sides, which leads to the lowering of his pelvis and his center of mass. He also briefly pushes hard to the side and then he pushes hard with his lead leg. So he produces a lot of force but also produces a lot of club head speed, about 120 miles per hour.
We'll let you see that one more time, right side load, shift and hard left side drive.