The science behind the golf swing

The golf swing begins in the positioning stage. This stage is the position that the golfer places their body in to begin the swing. According to Glenn Fleisig MD, the address position is a functional body position which includes the proper grip and body position. A balanced, "athletic" address position, which is consistent swing to swing, will provide the golfer with the correct starting position for the swing. Inconsistency in either how the body is set up or with the grip leads to inconsistency on shot to shot. The body in terms of muscle activity is fairly low at address. The muscles of the body are supporting the body in a specific anatomical position and preparing it to swing a club.

The back swing (take away) is when the body begins to move the club. The back swing is the portion of the swing that places the body in the correct position to begin the downswing. During the entire back swing the body begins the recruitment of energy that will be transitioned at the top of the back swing towards the ball. Key points from a biomechanical analysis of the back swing are: as the club moves backwards shear force is applied to anterior portion of the right foot, at the same time a posterior shear force is applied to the left foot (Fleisig, Biomechanics of Golf). This is the beginning of torque development in the body that will be transitioned into the club head at impact. Rotation of the knees, hips, spine, and shoulders continues during the back swing creating additional torque to be translated into the club head in later stages of the swing. The important point to remember in the back swing is that the entire rotation of these body parts occurs around an imaginary axis of the body. EMG activity is moderate during this stage of the swing as a result that the body during this portion of the swing is essentially creating/storing energy that will be released towards the end of the swing.

The completion of the back swing is what is termed the "transition" stage of the swing. The transition point of the swing is where the body finishes its backward movement and begins the forward movement of the swing. The best reference point of when the transition stage of the swing begins is when weight shift onto the inside of the right foot (right-handed golfer) is completed and movement back towards the left foot begins. The transition in terms of a time frame is very short and is completed when weight transfer begins to move forward, and the club completes its movement backwards. Research states that the transition of the swing is where additional elastic energy is stored within the body. This is a result of the lower body moving forward and the upper body still "coiling" backward. Studies show that at the completion of the transition (top of the back swing) the hips are closed to approximately 45 degrees and the shoulders are closed to about 100 degrees (Fleisig, Biomechanics of Golf).

After completion of the transition, the down swing into impact begins. Weight shift continues during the down swing. The generation of torque is created in the lower body and then transitioned up through the body into the club and eventually the club head. According to Fleisig, the majority of torque in the swing is generated by the lower body muscle groups of the glutes, hamstrings, quads, and core region (low back, abdominals, obliques). The torque created in the lower body creates acceleration in the upper body as energy is transferred into the club head. EMG studies indicate that there is moderate activity of the pectoralis major, latissimus dorsi, and rotator cuff muscles (Geisler, Kinesiology of the Full Golf Swing) during the downswing. The downswing is complete at the point in which impact occurs with the golf ball.

Impact with the ball occurs for approximately half a milli-second (Fleisig, Biomechanics of Golf). The purpose of impact is to hit the ball in the correct direction with the chosen amount of force by the golfer. At impact the weight transfer is complete. Shear force from both feet are towards the intended target. Research indicates that at impact the left foot (right-handed golfer) is supporting 80% to 95% of the golfer's weight (Fleisig, Biomechanics of Golf). Impact again occurs for a very short amount of time (.0005 seconds). Impact is the point at which the potential energy created by the body during the back swing, transition, and down swing is transferred into the club and club head. The potential energy created by the body is then transferred into kinetic energy as club head comes into contact with the ball.

After contact, the impact stage of the swing is complete and the follow through stage begins. The follow through is essentially the deceleration of the body after contact with the ball has been made. This is completed through the body rotating to a completion point where the club head is behind the golfer. Deceleration by the body occurs as a result of the absorption of energy back up through the kinetic chain of the body. Follow through is where the body slows itself back down and dissipates all the kinetic energy create by it, which was not delivered into the ball.