Vertical Forces

In my recent work with 2016 PGA teacher of the year Mike Adams, we’ve discovered the importance of large vertical ground reaction forces (GRFs) in the late downswing in increasing club head velocities and optimizing launch conditions (especially for the driver swings).

Dr. Sasho Mackenzie’s recent work in calculating the forces the golfer applies to the grip end of the club seems to support these findings. An example of this is in the late downswing when the forces on the handle are shown in the animation below for a driver swing (that was graciously provided by Dr. Mackenzie):

Screenshot of animation provided by Dr. Sasho Mackenzie

At this point in the golf swing, the golfer is almost entirely pulling straight up on the golf club with close to the maximum amount of force that is applied to the club at any point during the swing. In order to produce these large vertically directed forces on the club, it most likely critical that a golfer utilizes the large muscles of the lower body to push into the ground and create the appropriate reaction forces on the body that can then be transferred to the club. This is true in most sports when the body is called upon to produce extremely large forces, such as in Olympic lifting. Olympic lifting coaches teach their athletes to get into triple extension (hip extension, knee extension, ankle plantarflexion) in order to accelerate the bar upwards off the floor with maximum force. All three of these joint motions increase the force that is placed down into the ground, so that the reaction force can accelerate the body and the weight upwards. This triple extension position is shown below in both a power lifter and a golfer, each of these creating extremely large vertical ground reactions forces.

Power lifter and golfer in a triple extension position

We’ve also discovered an important pattern in the path of the Center of Pressure (COP) that relates to the ability of the body to produce these vertical forces. As can be seen from the pictures above, it is important that the COP is slightly forward (towards the toes) in order to produce the maximal vertical forces. A good demonstration in order to feel this is to stand, shift your pressure towards your heels, and then attempt to jump. The key to jumping is putting enough vertical force down into the ground that the reaction force acting on your body is greater than your body weight. Not very easy to do with your pressure on your heels, is it? This can also be seen in the following two swings by Justin Rose that were captured on the Swing Catalyst Motion plate:

Swing # 1 – Pressure more towards the heels and small vertical forces, maximum of 146%

Swing # 2 – Pressure more towards the toes and much higher vertical forces, maximum 182%

The golf swing has long been thought of as mainly a rotational movement, but we are now starting to realize that high rotational speeds are not the only way to speed up the club and produce powerful and efficient golf shots. Much more information regarding the discoveries we have made recently using the Swing Catalyst products will be presented in the upcoming Level 2 seminars. I hope to see many of you there.

Scott K. Lynn, PHD
Swing Catalyst Research and Education Director