5 Phases of a Golf Swing

Set-up and Posture

The set-up and posture phase are important for building a solid foundation prior to beginning the golf swing movement. This phase is essentially setting up posture, alignment, and balance as any slight inconsistencies in this may cause the rest of the motion to be compromised. Although swings can be tailored to suit an individual, figure 2 shows an ideal golf stance where the hands are under the chin, feet are just outside shoulder width apart, and the ball is positioned in line with the front foot. This creates a balance between mobility and stability by establishing a strong base of support, proper body alignment, and solid centre of mass for energy transfer (Wrobel et al., 2023).

 

Figure 2, ideal set-up and posture for a driver swing.

Source: (Bourque, 2016)

A major biomechanical principle required in this phase is stability. The weight must be evenly distributed between both feet and the centre of mass should be maintained. Keeping a stable base gives the best chance of optimising the swing without losing balance (Wrobel et al., 2012). Another crucial aspect of this phase is alignment, ensuring a forward-tilted pelvis and slight knee flexion. This assists in engaging the core and maintaining balance as the body begins the next phases where rotation is required (Zemková & Kováčiková, 2023).

 

Finally, although the body must be engaged, the muscles must stay loose to enable a turn of the shoulder during the backswing. If there is extra tension in the shoulder area, this can affect the kinetic chain which is an important principle used in the backswing phase (Bourgain et al., 2022). Even though this may seem like a basic movement of the golf swing, it is vital to ensure the remaining phases are done efficiently so that the ball travels as far as possible along the fairway.

​​Backswing

 

During the backswing phase, the body starts to load with potential energy that can be transferred at the top of the backswing into the downswing (Sheehan et al., 2019). The further back and more efficiently the club  is pulled back and up, the more likely the ball can be impacted with high power and accuracy.

 

Maximising angular momentum is vital in the backswing. The moment arm (left arm for right-handed golfers) must remain as straight as possible, increasing the amount of torque generated and rotational energy stored (Izumoto et al., 2019). Furthermore, a longer moment arm increases the moment of inertia, this in turn maximises the angular momentum if the golfer generates a solid amount of angular velocity through the clubhead (Hume et al, 2005). On the other hand, a bent moment arm will reduce the radius of the swing, decreasing the angular velocity and angular momentum generated. A comparison of a bent moment arm and a straight moment arm is shown in figures 3 and 4 below.

 

  Figure 3, bent moment arm.                                      Figure 4, straight moment arm

 

 

  

Another biomechanical principle which is vital in the backswing phase is torque. Torque develops around the spine and the hips through  eccentric muscle contractions (Nesbit and Serrano, 2005). Additionally, Ground Reaction Forces (GRF) start to accumulate as a lateral weight shift occurs to the trail foot and the kinetic chain begins (Bourgain et al., 2022). 

 

In this phase, leverage is a vital biomechanical principle that influences the power at which the ball is hit and the accuracy with which it travels. The shoulder is the primary fulcrum as the third class lever as the muscles through the upper arm apply forces (The Power Package, n.d.). Referring back to figure 3, a bend in the moment arm introduces the elbow as another fulcrum which is not ideal while aiming to hit a drive onto the fairway with good accuracy. Maintaining a single lever assists in the control of the clubhead angle and the energy transfer through the kinetic chain (Raatz, 2024). Figure 5 shows the fulcrum along with the force and the weight in a golf swing.

 

 

 

 

 

Figure 5, fulcrum, force, and weight in a drive

 

Source: (The Power Package, n.d.)

 

After all, the goal of the backswing is to store energy effectively and prepare the body for a strong, well-timed release, not to swing back as far as possible. Improved clubhead speed, accuracy, and consistency are the results of a well-performed backswing.

Downswing – Kinematic Sequencing and Energy Transfer

In golf, the downswing is an essential phase in generating clubhead speed. This phase begins at the top of the backswing and continues until the impact phase. Key to this phase is the kinematic sequence, where there is a coordinated rotation and activation of body segments in a proximal to distal manner. From the pelvis first, followed by the thorax, arms and Distal (club) (Cheetham et al., 2008).  

 

This kinematic sequence allows for effective transfer of angular momentum. This is because when each one of the body segments accelerates and decelerates, there is a transfer of energy to the next distal segment. An example of this is when the pelvis decelerates, there is a transfer of momentum to the thorax, this then leads to the arms accelerating and eventually the club. It is critical that this sequence is efficiently timed, as improper timing can lead to a leakage of energy. In turn this will result in reduced clubhead speed (Lindsay et al., 2022).

 

Furthermore, ground reaction forces (GRFs) play a crucial role in the downswing. When the lead foot pushes into the ground, this produces vertical and horizontal force that supports the rotation of the pelvis and shifting weight forward. According to Newton’s Third Law, every action has an equal and opposite reaction. Therefore, as the lead foot is forced into the ground, the ground responds with a force that contributes to upward and rotational acceleration of the body. For maximum efficiency, it is important that this movement of force peaks early on in the backswing (Ball & Best, 2007).

 

Another significant biomechanical feature of the downswing is the thorax-pelvis rotation difference, or the X-factor stretch. A greater separation angle during the transition into the downswing, achieved by keeping the thorax back whilst advancing the pelvis is responsible for larger elastic energy storage in the torso muscle. This pre-stretch enhances rotational torque, leading to increased rotational energy, overall resulting in increased clubhead velocity (Myers et al., 2008).

 

Impact – Kinetics, Joint Angles, and Energy Transfer

Impact occurs when the clubhead strikes the golf ball. However, from a biomechanical perspective it is the conclusion of all the movements that have occurred before. At the point of impact clubhead velocity is maximised by the effective release of stored energy and the maintenance of proper joint positions to ensure square impact. At impact, it is vital that the clubhead is travelling at peak linear velocity. This is mostly a function of lag angle created earlier in the swing. Precisely, the angle formed by the lead forearm and the club shaft. Preserving the lag deep into the downswing stores potential energy released explosively when the wrists unhinge (Zheng et al., 2008). Early release negates energy transfer to the clubhead and in turn creates less desirable speed and ball contact.

·  Lead wrist: Slightly extended and ulnar-deviated, stabilising the clubface.

·  Trail wrist: Flexed and radially-deviated, contributing to late club release.

·  Elbows: Slight extension to maintain the arc without “casting” the club.

·  Spine and pelvis: Minimal lateral flexion; pelvis slightly open to the target (~30–40°), thorax less so (~10–20°), reflecting continued rotational flow.

Joint mechanics also regulate clubhead speed and direction. The lead wrist if often extended and ulnar deviated, and the trail wrist is flexed, preserving the final uncoiling motion. This joint position reserves swing arc integrity and promotes favourable launch conditions. Further, maintaining spine angle at impact allows efficient transmission of rotational energy down the arms to the club.

 

Kinetically, upper body and lower body force transmission are maintained by impact. The lead leg, being now typically extended, acts to brace the body and provide a pivot point around which energy transfer can further take place. Weight transfers onto the leading side of the body during this phase ensures that the body mass is assisting the strike, adding clubhead velocity and ball speed.  

 

Follow through

Although the ball has been hit, the follow through phase is important for controlling forces developed previously. This phase consists of the slowing down of the club and parts of the body in a controlled and safe fashion. The follow through phase is also important for the longevity of physical wellbeing and performance. An efficient follow through involves eccentric muscle activation, through the engagement of the core and upper body muscles to successively decelerate the arms and the golf club. Often the slowing down is widely underappreciated biomechanical skill that saves joints like the shoulders, elbows and spine from injury (Gluck et al., 2008). A smooth follow through also enables complete trunk and pelvis rotation so that the swing energy is utilized to the maximum instead of being suddenly terminated.

 

In order to analyze the biomechanical principles of clubhead speed, angular velocity was calculated throughout the downswing phase from a side on video recording of a golfer. The change in displacement was measured from the top of the back swing to the impact on the ball.  Two calculations were utilized to simulate the performance under altered timing.