An understanding of golf swing biomechanics is integral to improvement in the golf swing. Through biomechanical studies by the American Sports Medicine Institute (ASMI) located in Birmingham, Alabama a sequential model of the golf swing has been developed.
Through the utilization of this model in conjunction with the kinematic sequence we can review the golf swing and determine the necessary physical requirements of the body for the execution of a biomechanically efficient golf swing in which the kinematic sequence remains intact. ASMI has broken down the golf swing into the following series of biomechanical movements: Set-up, Backswing, Transition, Downswing, Impact, Follow Through.
In order to better understand the connection between the kinematic sequence, golf swing, the body, and the interaction of these three entities, we will look at each phase of the golf swing from a biomechanical perspective.
The set-up position often referred to as the address position, is the position in which the golfer places the body to begin the golf swing. According to Glenn Fleisig MD, the set-up position is a functional body position, which includes the proper grip. 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 from 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 to swing the club.
The backswing is when the body begins to move the club. The backswing is the portion of the swing that places the body in the correct position to begin the downswing. During the entire backswing the body begins the recruitment of energy that will be transitioned at the top of the backswing towards the ball.
Key points from a biomechanical analysis of the backswing are: as the club moves backwards, shear force is applied to the 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 clubhead at impact. Rotation of the knees, hips, spine, and shoulders continues during the backswing.
This creates additional torque to be translated into the clubhead in later stages of the swing. The important point to remember in the backswing is that the entire rotation of these body parts occurs around an imaginary axis of the body. The body during this portion of the swing is creating and storing energy to be released towards the end of the swing.
The biomechanical analysis of the backswing indicates this is the stage of the swing at which power development (clubhead speed) begins. The process by which this occurs is through the creation of torque, and the development of torque by the body requires rotation.
Rotation in the lower body, torso, and shoulders is contingent upon a number of physical parameters such as joint range of motion, muscular flexibility, and segmental strength in the lower body, hips, core, and upper back. If any of these physical entities (flexibility, strength) are lacking, the ability to execute the backswing and develop torque will be diminished.
The completion of the backswing 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. The best reference point of when the transition stage of the swing begins is when weight shift onto the inside of the right foot is completed (right-handed golfers) and movement back towards the left foot begins.
Research indicates 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 as the upper body continues to coil backward(X factor). Studies show at the completion of the transition (top of the backswing) the hips are closed approximately 45 degrees and the shoulders are closed to about 100 degrees. (Fleisig, Biomechanics of Golf)
After completion of the transition, the downswing begins. Weight shift continues during the downswing. The generation of torque is created in the lower body and then is transitioned up through the body into the club.
The majority of torque in this phase of the swing is generated by the glutes, hamstrings, quads, and core musculature (lower back, abdominals, obliques) of the body. (Fleisig, Biomechanics of Golf) The torque created in the lower body creates acceleration in the upper body as energy is transferred onto the clubhead.
Studies indicate there is moderate muscular activity in the pectoralis major (chest), latissimus dorsi (upper back), and rotator cuff muscles during the downswing. (Geisler, Kinesiology of the Full Golf Swing) The downswing is complete at the point in which impact occurs with the golf ball.
Keeping the kinematic sequence in place during the downswing allows for the generation and transfer of speed into the golf ball. In order for this to occur, high levels of neuromuscular efficiency, strength, and power are required in the lower body and core. This allows for power to be generated by each of these segments, transferred efficiently to the next segment of the body, and in addition, allows for each of these segments to slow down once energy has been transferred to next.
It is important to note how dependent the kinematic sequence is upon the physical entities of the body to achieve this outcome. A golfer lacking physical strength, power, or flexibility will struggle to develop speed and transfer this speed to the golf club during this phase of the golf swing.
Impact is the point at which the potential energy created by the body during the backswing, transition, and downswing is transferred into 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.
At impact, weight transfer is complete. Shear forces from both feet are towards the intended target. Research indicates at impact the left foot (right handed golfer) is supporting 80 to 95 percent of the golfers weight. (Fleisig, Biomechanics of Golf)
Execution of impact requires the release of the hands with correct timing for transfer of power to clubhead. In order to perform the wrist release into impact, shift weight correctly, sequence the transfer of energy through the body, and release speed into the golf ball, all phases leading up to this point must be execute correctly.
Errors in the kinematic sequence or phases of the golf swing caused by physical limitations, poor mechanics, or improper equipment will affect impact. Physical impedances to the golf swing such as a lack of mobility, flexibility, limited stability, or a lack of power development will show up at impact relative to ball flight, distance, and direction.
One common physical limitation viewed in many golfers is a lack of stability (strength) in the core section of the body. This limitation impedes the ability to maintain a fixed spine angle and develop torque, both of which become very apparent at the impact position of the golf swing.
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 clubhead is behind the golfer.
The follow through is where the kinematic swing ends, energy not transferred into the golf ball is dissipated, and the body slows itself back down.
Information on the kinematic sequence and biomechanics of the golf swing provides an insurmountable amount of information about the golf swing. These segments of information provide any golfer, swing coach, or conditioning coach with a great deal of insight on how speed is developed in the swing, how energy is transferred to the clubhead, and what is physically required of the body to perform the golf swing efficiently.
We know limitations in mobility, flexibility, neuromuscular efficiency, stability, and/or power will cause limitations in the execution of a biomechanically efficient golf swing as well as negatively affect the kinematic sequence, resulting in less accuracy and distance on every shot.
Sean Cochran is one of the most recognized golf fitness instructors in the world today. He travels the PGA Tour regularly working with professional golfers. To learn more about Sean Cochran and his golf fitness exercises and training programs go to http://www.seancochran.com.