The Perfect Golf Swing Mechanics

Many golfers are in search of the perfect golf swing. As a golf coach and biomechanist, I’m sad to inform you that one perfect golf swing does not exist. However, the science suggests great golfers’ swings do have many things in common.

In this article we’ll cover a quick overview of what we mean when we say a perfect golf swing, we’ll then dive into swing mechanics that great golfers exhibit. To summarise we’ll then discuss what this means for your golf game. Grab a coffee and have a read, or use the table of contents below to jump to your preferred section.

This article is a little geeky so if you want a simpler guide check out this guide on how to swing a golf club or this piece for some great golf swing tips.

The perfect golf swing maximises performance not positions

Below we have four golfers who have made it to men’s world #1 – it is quite evident their golf swings all look different. What they have in common is what their golf swings provide. Their golf swings all deliver the following qualities:

• High levels of shot accuracy.
• High levels of repeatability in shot outcome.
• Good ability to generate shot distance.
• Adaptability of ball flight trajectory.
• Keep them free from injury (most of the time).

With this in mind we know our quest for the perfect golf swing is an action that delivers performance rather than textbook positions. This also hints at something we’ll discuss later on – forces are what really count in the golf swing.

Below we’ll run through the science of great golf swing mechanics phase by phase:

Backswing mechanics

Lower body swing mechanics

Despite modern-day players showing less lateral movement during their backswing, they still transfer most of their weight onto their back foot (65 – 85%). Like any throwing action this allows the player to push off through their back foot during the downswing and begin to effectively unwind their body towards the target.

What has changed in modern times is how the legs and pelvis move to create this loading during the backswing.

Historically, the back knee would extend (straighten) and the front knee flexed. Meaning, when you look face-on at a golfer, the right hip would appear higher than the left, and the left leg appeared to fold inwards. This move allowed the pelvis to rotate more freely away from the target, creating a long backswing, but without effectively storing potential energy.

Modern golf swing mechanics often prefer players to maintain flex in their right knee, and have far less displacement in the position of their left leg from setup. This creates a picture from face on where the left and right hips appear more level. There is also a greater focus on players maintaining their posture (left and right hip flexion) as they reach the top of their swing – the rationale for these positions is to maximise our use of the stretch-shortening cycle.

The stretch-shortening cycle underpins many athletic movements, including the golf swing. Essentially, if we stretch a muscle group before we maximally contract it, we can generate more force. In some cases up to 60% more force. We used to think this was purely due to the stored mechanical energy, like stretching an elastic band, but nowadays we know the process is far more complicated (lots or neural stuff).

If we retain our right knee flexion throughout our backswing, we keep the quadriceps in a lengthened state, our hamstrings and gluteals are also lengthened when we maintain hip flexion (maintaining posture). All of the muscle groups above are further lengthened as the pelvis rotates away from the target during the backswing.

These swing mechanics are shown brilliantly above by Rory McIlroy. They have the effect of pre-loading large muscle groups in the lower body, ready to generate some serious speed in the downswing.

Individual differences in hip rotation

10 – 15 years ago there was a strong school of thought that the hips should be restricted from rotating during the backswing, in order to increase the separation between the pelvis and upper body. This concept has some merit, but can increase the risk of injury, and actually reduces the stretch-shortening benefits in the lower body detailed above.

Today, an increasing number of golf coaches are advising more hip rotation during the backswing, thankfully (‘getting deep into your right hip’ is the hot phrase I’ve heard used to describe this move). As your pelvis rotates posteriorly you should feel your weight shifts slightly towards the heel of your back foot.

The optimal swing position to achieve this effect will vary for every golfer. Size, range of motion, strength, flexibility and tendon stiffness will all play a role. It is important for coaches and players to aim for an optimal mechanistic backswing for each player, not merely placing each player into the same position.

Key takeaway

Use your lower body to create a subtle, but powerful backswing position. Think less about textbook pictures and more about the dynamics of your golf swing.

Upper body swing mechanics

As the lower body does its thing to load and store power, the upper body makes a large rotation. The face-on video of Brooks Koepka below provides a great example of this.

As coaches, we often talk about shoulder rotation, but what we are actually looking at is the separation between the pelvis and thorax – known as thoracic rotation. This movement comes mainly from 12 vertebrae in the mid-section of your spine. The rotation is a result of many muscles around your mid-section contracting and relaxing in harmony.

A fundamental requirement for great upper body rotation is having a great posture at set-up. A hunched posture prevents your thoracic spine rotating, and adds extra load onto your lower back (lumbar spine), which isn’t designed to rotate in the same way. This is a common cause of injury in many golfers suffering from lower back pain.

A common misconception I would like to cover is how much thoracic rotation elite players exhibit during their backswing. Many amateurs believe elite players achieve 90 degrees of rotation, but when you model the golf swing in 3D and take the pelvis rotation into account elite players actually create, on average, 70 ± 20 degrees of rotation between their pelvis and thorax. Using some simple stats we can infer that 68% of elite players achieve somewhere between 50 to 90 degrees of thoracic rotation – far less than you might imagine. The rest of that rotation you see comes from internal and external hip rotation.

Key takeaways

Great posture at set-up is a must for great upper body swing mechanics. Elite players create 50 – 90 degrees of thoracic rotation, the rest comes from hip rotation. Try not to create more thoracic rotation than you are capable of, it isn’t necessary. Secondly, value how important hip rotation is in the modern golf swing. Look after and strengthen your hips – to do so you can check out this article for more ideas on improving strength and mobility in your hips.

Shoulders, arms and wrist mechanics

As your lower body and trunk are priming for force generation, your arms and wrists are predominantly determining what direction you launch that golf ball. As long as you strike the centre of the club face, accuracy is a product of your swing path and club face through impact.

During your backswing, both your shoulders and forearms rotate as your right elbow flexes, these actions keep the golf club arcing around your body. The more rotation from your shoulders and forearms, the flatter the shaft angle and more laid off the club will appear at the top of the backswing. The exact contribution of rotation from 1) shoulder rotation and 2) pronation/supination of the forearm is not clear – it is tricky to measure, even with 3D equipment. We can assume elite players show some variance in this area, as I’ll talk about later in this article.

Suggesting how the arm swing mechanics discussed above affect impact is not a straight forward debate. It will depend on pelvis, trunk mechanics and inertia forces of the arms and club as they reach the top of the backswing. But simply speaking, the more the arms rotate, and the more the club is laid off, the easier it is to create an in-to-out swing path. Less arm rotation creates a steeper shaft angle and an across the line position, which likely results in a more out-to-in swing path.

Wrist mechanics in the backswing

Wrist mechanics play two key roles during the backswing. Firstly, radial deviation creates a powerful lever system between the arms and the club, commonly called wrist hinge. Secondly, wrist flexion/extension manages the relationship between the club face angle and the arms. The third range of motion (pronation/supination) actually comes from the forearm and was discussed in the previous section. If you want to learn more about the wrist flexion/extension of elite players you can see a couple of the swing drills Justin Rose and Tommy Fleetwood use here.

Many beginner golfers struggle to create effective wrist mechanics, with the root cause commonly being a poor golf grip. If the golf club is gripped too close to the wrist joint in the left hand (near the centre of the palm), the left wrist becomes flexed at set-up to help square the clubface to the target. This position limits radial-ulna deviation (wrist hinge) resulting in golfers forcing the wrist to do something it isn’t primed to do. The first port of call in resolving poor wrist mechanics is to master your golf grip.

As the image below shows, elite golfers also show great variance in wrist mechanics during the backswing. The club face angle we see at the top of the backswing is a product of a player’s golf grip at set-up and their wrist flexion/extension at the top of the swing (we normally just look at the left wrist angle for simplicity).

The weaker the golf grip and the more extended the left wrist, the more open the club face will be relative to the body motion – generally leading to more fades and slices. The stronger the grip at set-up and the more flexed the left wrist, the more closed the club face will be (see DJ above), leading to more draws and hooks.

There is no ideal relationship or perfect club face angle in practice. A player’s optimal club face position needs to be married into a players release characteristics and desired ball flight.

Variability in golf swing mechanics

The arms and wrists contain many degrees of freedom, meaning we often see trial-to-trial variance that is much higher in the arms and wrists than in the trunk. We often think of variability as a bad thing in the golf swing, and yes, elite tour pros are far less variable than a 20 handicapper when it comes to swing-to-swing variance. But more recent research is starting to suggest elite players also show more functional variance in their golf swing mechanics.

From this perspective, elite players are more capable of returning the club head back to their ideal impact position from many different backswing positions. Less-elite players may show similar levels of variability in their backswing positions, but are not able to generate an ideal impact position from all of these permutations.

Downswing mechanics

Onto the downswing. As with the previous section, I’m not going to pretend I have the secrets to the perfect downswing. Instead, we’ll discuss the key movements and I’ll do my best to explain the science behind why these movements are important. We begin with the the ground reaction forces that cause the movements we see.

Ground reaction forces & golf swing mechanics

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All successful striking actions (golf, tennis, baseball) start from the ground. If this seems counterintuitive, just go find your nearest ice rink and see how you fair hitting a driver. Ground reaction forces (GRF) are the forces that result from us pushing against the ground. We push against the ground and an equal, and opposing, force pushes back up into our body – this force initiates a lot of the movement we see in the golf swing.

Ground reaction forces are invisible without the use of a force plate (blue arrows in the images above), which makes wrapping your head around them quite tough. But trust me, they are always there and they are fundamental to great golf swing mechanics.

Research has consistently shown elite golfers generate higher levels of vertical GRF (pushing down), relative to their body weight, early-to-midway in their downswing. This makes good sense – as higher forces lead to greater acceleration of objects (F = m.a).

However, more recent research has looked into anterior-posterior (forward-back) and medial-lateral (sideways) forces. Elite players also generate greater anterior-posterior forces (one foot pushing forward, the other pushing back) during the start of their downswing. These forces are potentially more interesting, as they create torque in the lower body, and cause the pelvis to rotate towards the target. The bigger these forces, over a longer period of time (greater impulse), will lead to a greater rotational acceleration of the pelvis – Rory McIlroy’s pelvis rotation comes to mind.

Key takeaway

To create a powerful golf swing you need to be able to apply large forces into the ground – downwards, in order to create friction, but more importantly, pushing backwards with your front leg and forwards with your trail leg.

Conditioning will play an important role, but also consider players squatting motion at the start of your downswing. Optimal flexion in the hips and knees will differ from player to player, but each individual will have a sweet spot for applying larger ground reaction forces.

Body swing mechanics during the downswing

The most well known aspect of golf swing mechanics is the beautiful sequence we see Tiger portraying below:

1. A slight shift of weight
2. Rotation of the pelvis
3. Rotation of the thorax
4. Rotation of the shoulders, forearms and ulnar deviation (release)

This is known as a kinematic sequence (sequence of movements) and it takes advantage of the summation of speed principle, where energy is generated in one segment, before being passed onto the next (pelvis > thorax > arms > club). The stretch-shortening cycle discussed in the backswing section is a key mechanism underpinning this sequence and how much additional energy can be passed on from one section to the next.

If this sequence can be well-timed, it results in each body segment generating a higher speed than the last, with peak club head velocity being achieved close to impact.

Why amateurs struggle with this sequence

For many golfers this sequence is the holy grail, but most struggle – why they struggle is the million-dollar question. Recently, there has been a trend to fix physical limitations and there is no doubt that reduced mobility, stability and strength may inhibit golfers from achieving this sequence.

I’m not going to disagree, but here I would like golfers to realise that this sequence starts with ground reaction forces. Too many players try to mimic pelvis rotations of great players, when in fact great players show these movements as a consequence of the forces applied through their feet into the ground. Start with you feet and apply forces – the rest will follow.

Elite golf swing mechanics and sequencing

Although all professionals show similar patterns in their sequencing, there is no magical formula – just look at the videos of Rory, Brooks and Tiger in this article, they all vary; even to the naked eye. Elite players find a unique solution that helps them generate high club head speed whilst controlling the club head orientation through impact.

Nonetheless, there are some clear differences between elite and amateur players. Elite players show greater levels of rotational pelvis acceleration early on in the downswing, they then show a deceleration as they reach impact. This sounds counterintuitive but results in more energy being transferred to the thorax (see the image above). The second effect is that the pelvis is now rotating slower through impact (remember deceleration doesn’t mean zero velocity), potentially offering more control during this critical time.

Key takeaway

A great kinematic sequence starts from the ground, not the pelvis. Executed correctly, the pelvis reaches its peak angular velocity early on in the downswing, before slowing, not stopping, as it continues through impact.

Body swing mechanics moving towards impact

There is one more area of swing mechanics that falls outside current biomechanics research and falls more into the realm of modern coaching. I think it’s interesting to talk about, so I’ve discussed this briefly below.

In the 1960s and 1970s great players showed a lot of lateral movement as they moved into impact, caused by lateral joint actions at the ankle, hip and spine. These days we see a very different motion through impact, where players have far less lateral action and more rotation. Here we will discuss the lower body mechanics specific to this modern approach.

As discussed previously, modern golfers rotate their pelvis aggressively early on in the downswing, the pelvis quickly returns to its position at set-up and begins to rotate towards the target. It has passed on its energy, but if it stops rotating completely it will spark off a chain reaction that prevents many good ball strikers from becoming exceptional.

If the pelvis stops completely before impact, the thorax and arms will abruptly slow down too. The club head has been aggressively accelerating and cannot be slowed down. The consequence is the club head carries on and we see a breakdown between the angle of the club and left arm. This results in limited control of where the club face points through impact. We often see players hands flip over as they struggle with wild hooks.

To prevent this from happening the lower body creates some nifty adaptations. Near to impact, elite players continue to apply force to the ground through their back foot. Their right hip extends through impact, which forces the pelvis to keep turning. Many elite players also extend the left knee and hip slightly through the hitting zone, which gives the left side of the body more capacity to rotate and keeps the pelvis moving. This is demonstrated beautifully by Tiger Woods in the sequence above. The visual result is a solid left side, with the rest of the body rotating about the left leg.

Key takeaway

Great lower body action is the key to mastering club face control and accuracy through impact. The right side pushes, as the left side affords room for the pelvis to keep rotating. A great golf coach will make subtle changes to your posture, stance and weight distribution to help you find your solution.

Release and arms mechanics

How the arms and wrists move in an elite player is an under-researched topic in biomechanics and can still divide coaches. Some golfers incorrectly assume the arms do nothing during the downswing, they merely follow great body motion, but I would disagree. Personally, I feel great arm mechanics can elevate a player considerably once they have sound body mechanics in place.

A scroll back up to Tiger’s swing sequence will show you that early on in the downswing the left shoulder horizontally extends, bringing the club back in front of the chest. Many golfers including Tiger and Justin Rose talk about their arms falling down before they rotate their body through. Whereas amateur players often feel their body needs to do all the work whilst their arms stay passive.

This is the difference between feeling and doing in golf. The perfect golf swing is a blend of body rotation and arm swing. Most golfers have one aspect that lags behind the other and often requires extra attention.

If the downswing is started correctly you’ll get to a position similar to Rory and Tiger below. You can call this ‘the slot’ or pre-impact but it is a position where the club face and body is primed to deliver the club into impact.

This is the position where all professional players look very similar, not identical. You need to be roughly in this position to deliver the club squarely and powerfully, but your perfect position will depend on your body mechanics, club face angle and the shot shape you wish to hit.

Let us look at what great players do from here, this is worth sharing.

The difference between amateurs and elite players swing mechanics

Once the club falls back down parallel to the ground we great players rotate to square the club face up at impact. The forces created by the summation of speed automatically cause the release of any wrist hinge into impact (ulnar deviation).

This area of swing mechanics is potentially the most misunderstood by amateur golfers. Amateur players often feel they have to use their wrists to square up the club face. However, when you look through all of the swings featured in this article, you’ll notice elite players show minimal changes in wrist flexion/extension. The club face is controlled through body rotation and pronation and supination in the forearms.

If there is anything close to a secret to the perfect golf swing, it is understanding this relationship between the arms and how they control the club face rotation during your golf swing.

Great golfers get into the position above then use the body and arms to rotate through impact – there is very little active hand action.

Key takeaway

The arms play an important role in your downswing mechanics. Becoming an exceptional ball striker requires getting to grips with how body rotation and pronation/supination control your club face during your downswing and through impact.

Building your perfect golf swing

So what does this mean for your golf game? In this article, I wanted to share the detail – the biomechanics behind the perfect golf swing. Hopefully, the understanding has helped you build an idea of what great golf swings look and feel like.

However, playing golf is different to the theory. Below is my summary of what I feel golfers should take away to become better players:

Your backswing should involve a turn and a shift of weight – what that looks like depends on your body type. Develop a golf grip, arm swing and left wrist position that sets the club face in a neutral position.

Start your downswing with a blend of body rotation and arm swing – what this will feel like depends on you and what is currently too active. Half way down you should have the club set in a position not identical, but closely resembling great players – pay particular attention to your club face angle at this point. 2 – 3º makes a large difference in accuracy.

From here the move through impact is mainly body rotation and some arm movement. Great players pre-set everything before impact and rotate through using their big muscles.

Finally, don’t loose sight of the end goal. Your aim is not to have a textbook looking swing, but rather to find a motion that hits the ball straight, is repeatable and keeps you free from injury.

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Happy golfing – Will @ Golf Insider UK

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