Biomechanics of the Golf Drive

THE ANSWER

What does the optimal movement pattern of a golf drive look like?

There are four distinct movement phases a golfer completes when executing a golf drive. These include the: pre-swing phase; backswing phase; downswing phase; and follow through phase. Australian golfer and current World number 1 Jason Day will be used as an example to explain the fundamentals of each of these phases.

Pre-Swing Phase

The initial set-up of a golfer is critical towards successful execution of the golf drive. In the pre-swing phase, many golfers tend to stand with their knees slightly bent, legs approximately shoulder-width apart, adopt an interlocking, overlapping or baseball grip, and their weight heavily distributed towards their back leg (Hume, Keough & Reid, 2005). This allows for a well-balanced stance position in which the golfer’s centre of mass fits well within their base of support, allowing for greater stability prior to the backswing phase (Blazevich, 2010). It is also noticeable that Jason has his hands as high as possible on the grip of the golf club; this ensures maximum power production by altering his ability to positively change the effect of the inertia in the club itself to produce optimum distance (Blazevich, 2010).

Jason Day displaying an ideal set up position in the pre-swing movement phase

Backswing Phase

The backswing movement phase sees the golfer take the golf club back behind their head in order to store maximum power prior to the downswing phase. Force of the club head is increased in this phase by cocking the wrists at the end of the backswing phase which conserves angular momentum, as well as having an open kinetic chain movement evident with a push-like movement pattern of the straight front arm, and a throw-like movement of the bent back arm (Blazevich, 2010). In essence, the front arms increases the accuracy of the drive, and the back arm provides the power to facilitate maximum distance.

Jason builds angular momentum in his backswing by cocking the wrists and ensuring the club is perpendicular to his arms near the end of the backswing phase

Downswing Phase

The downswing phase sees the golfer release the elastic energy in the club head, which has been built up in the backswing phase in stretched muscle tendons, into the ball upon ball impact. With reference to Newton’s second law of motion, acceleration of the club head is crucial towards achieving maximum force production being transferred into the golf ball, resulting in maximum distance through the impulse-momentum relationship (Blazevich, 2010). Also notice that upon ball impact, Jason’s back arm and front leg respectively have almost fully extended, allowing for maximum momentum to be transferred into the golf ball.

Jason applies significant acceleration in the downswing phase to increase club head velocity upon ball impact

Follow Through Phase

The follow through phase of the golf drive sees the golfer fully extend both arms and finish with their hands behind their head. In order for optimal movement, both arms must remain straight for as long as is comfortable to transfer maximum force into the golf ball and hence providing maximum distance. It is clearly evident that Jason has close to no weight distributed on his back leg in this phase, as his back foot is barely touching the ground; this indicates that full weight transfer has taken place, whereby changing the effects of his inertia has resulted in maximum force production and club head velocity (Blazevich, 2010).

Full extension of his arms sees Jason transfer maximum momentum into the ball upon ball impact

How does the set up stance of the golfer contribute towards optimising maximum distance?

Bent Knees

There are a number of technique fundamentals in their set up that are present in many professional golfers. Examining Jason Day’s set up position, the slight bend of his knees enables his centre of mass to be closer to his base of support, improving balance and stability in the pre-swing movement phase.

The slight bend in Jason's knees allow him to maximise his force production in club head velocity in the pre-swing phase

Additionally, the bent knees also contributes to an increase in a phenomenon known as a ground reaction force (GRF) between himself and the ground. GRF is based upon Newton’s third law of motion, and explains how applying additional force into the ground surface will result in a greater reactionary GRF and therefore summation of force throughout Jason’s body (Blazevich, 2010). Moreover, as Day begins his backswing, this force transfers from the ground, up his lower limbs (feet, knees and hips) to his upper limbs (chest, shoulders and arms) and is ultimately transferred into the head of the golf club itself, ready for when he initiates his downswing (Hume, Keough & Reid, 2005). In effect, an increase in the impulse-momentum relationship between Jason’s body and the club head results in a greater club head velocity, and an increase in elastic energy being transferred into the golf ball upon ball impact (Blazevich, 2010). By applying a greater GRF through faster club head velocity generation, optimal displacement of the golf ball can be achieved upon ball impact (Blazevich, 2010).

Wider Stance & Position of Ball

Balance and stability are key components of the initial set up to maximise distance. For an iron shot, many golfers tend to adopt a stance which sees their feet being approximately shoulder-width apart, and ball placement equally distributed between each leg. However, with the golf drive being a more powerful movement sequence, golfers tend to widen their stance ensuring they are more stable upon ball impact, as well as a different placement of the golf ball compared to an iron shot, where the ball is placed just inside the golfer's front toe (Hume, Keough & Reid, 2005). Biomechanically, this enables the golfer to execute a longer backswing and downswing motion, highlighting a period of increased kinetic energy in the club head prior to ball impact (Blazevich, 2010). Lastly, by widening their base of support prior to the swing, the golfer’s centre of gravity is in an ideal position to enable perfect ball strike and hence maximising distance (Blazevich, 2010).

A different position of the ball in the pre-swing phase is required to accommodate the longer lever of the golf driver, in comparison to an iron club


A wider stance provides increased balance and stability in the powerful golf drive movement sequence

Weight Distribution

Weight transfer throughout the golf swing adds another crucial component towards optimising maximum distance. As is seen in many professional golfers, their weight distribution in the pre-swing phase is heavily favoured towards their back leg. As the backswing movement phase takes place, weight remains of their back leg however as the downswing phase begins, weight begins to shift from the golfer’s back leg to their front leg through internal hip rotation of the back leg and upon ball impact, the weight is now heavily distributed towards their front leg. In effect, the inertia of the golfer has been redistributed to facilitate maximum force production (Blazevich, 2010). Based upon Newton’s first law of motion, it is impossible to change to mass of the golfer however by redistributing the golfer’s weight throughout the golf swing, has altered the effect of the golfer’s inertia and can therefore produce maximum distance out of the golf drive (Blazevich, 2010).

Jason Day showing little to no weight being distributed on his back leg once ball strike has been achieved

How does cocking the wrists in the backswing phase assist in achieving maximum distance?

The cocking of the wrists in the later stage of the backswing movement phase allows for maximum force to be stored prior to the downswing phase. Optimal execution of this technique sees the golfer have cocked wrists when the club is at a perpendicular angle to the arms in the backswing phase. The law of conservation of momentum explains that the total angular momentum of a system remains constant unless external forces influence that system (Blazevich, 2010, p. 91). As the cocking of the wrists highlights a period of angular velocity in the backswing phase, angular momentum is increased (Blazevich, 2010). Moreover, this technique highlights a period of increased rotational force known as torque in the backswing phase, providing an advantage in club head speed upon ball impact (Blazevich, 2010). As the downswing begins and the wrists uncock, angular momentum is transferred from the wrists to the club head of the golf club, releasing elastic energy and resulting in an increased club head velocity upon ball impact (Blazevich, 2010).

Having cocked wrists when the club is perpendicular to the arms allows for conservation of angular momentum in the backswing phase

What does a golfer need to do with their arms in the backswing movement phase to optimise distance?

In the backswing movement phase, it is imperative that the golfer’s lead (front) arm remains as straight as possible, and the trail (back) arm has a slight bend to it. This technique works to the biomechanical principles of push-like and throw-like movements of the kinetic chain (Blazevich, 2010). In essence, the front arm acts as a push-like movement pattern as all joints in the arm simultaneously move in the same direction, leading to an increase in accuracy of the golf drive (Blazevich, 2010). In contrast, the back arm acts as a throw-like movement pattern as the joints of the arm extend sequentially, one after another (Blazevich, 2010). By extending sequentially, the back arm of the golfer releases elastic energy into the club head, resulting in a greater club head velocity and ultimately, an increased force being transferred into the golf ball upon ball impact.

PGA Golfer Sergio Garcia displaying push-like and throw-like movement mechanics in the backswing phase to maximise distance

How does the shoulders of the golfer assist in achieving greater angle of release?

The angle of the shoulder complex upon pre-swing is vital towards achieving maximum distance. As the golf ball acts as a projectile once hit, projectile motion principles are applicable. The trajectory of the golf ball can be affected by external factors which are out of control to the golfer, such as a negative vertical gravitational force and horizontal air resistance (Blazevich, 2010). However, the angle of release, or the angle that the ball is hit, can be manipulated to enhance maximum force production. By having a slight upward tilt in the pre-swing movement phase, the golfer has a head-start in terms of being able to hit under the ball more and therefore, the ball having an increased vertical velocity (Blazevich, 2010).

The upward tilt of the shoulders puts the golfer in an optimal position to achieve the greatest angle of release possible

This upward tilt is also essential to ensure the body to rotate properly throughout the golf drive, whilst transferring weight from the back leg to their front leg. In effect, this technique assists in redistributing the golfer’s inertia in the early stages of the backswing phase, allowing for the effects of inertia to be redistributed to facilitate maximum force production (Blazevich, 2010). This technique, in conjunction with the natural backspin the golf club imparts on the golf ball upon ball impact (to work against the force of gravity to increase the time the ball spends in the air) results in optimal ball displacement (Blazevich, 2010).

How else can we use this information?

The biomechanical principles explored in the golf drive are applicable to many other sports whereby the sportsman uses an object as a lever to hit a ball. A baseballer preparing to hit a thrown pitch is very similar to the golf drive whereby, the hitter stores angular momentum in the backswing phase, accelerates the bat head through the downswing phase and follow through with push-like movement mechanics to hit the ball as far as possible (Blazevich, 2010). Additionally, weight transfer from pre-swing phase to follow through phase highlights the requirement of an adequate GRF, indicating an impulse-momentum relationship would be vital towards successful execution of the shot.

Many of the biomechanical principles involved in a golf drive are similarly present in a baseball hit

Another example includes a batsman in cricket whereby, they utilise their bat as their lever to generate maximum force production to result in maximum distance. Like the golf drive, the batsman exhibit a backswing phase in order to conserve angular momentum, accelerating the bat through the downswing phase to facilitate kinetic energy being transferred into the ball upon ball strike, as well as a push-like front arm/elbow to ensure optimal accuracy of the shot (Blazevich, 2010). Whilst many batsman have different techniques, the presence of an impulse-momentum relationship initiated in the pre-delivery phase ensures maximum force production and therefore maximum distance the batsman can hit the ball.

Conservation of angular momentum, push-like movement mechanics and the impulse-momentum relationship are all relevant in a cricket hit

References

Blazevich, A. (2010). Sports biomechanics, the basis: Optimising human performance. A&C Black.

Hume, P., Keogh, J. & Reid, D. (2005). Review Article: The Role of Biomechanics in Maximising Distance and Accuracy of Golf Shots. Journal of Sports Medicine. 35(5), 429-449.