Golf: the gentle game that can lead to pain

Studies investigating the axial forces at play during the swing motion have come up with some startling findings. One of the first studies looked at forces on the lower back during a full golf swing while using a five iron – specifically the compressive, shear, lateral-bending and rotational loads on the L3/4 segment of the lumbar spine⁽¹⁴⁾. Kinetic and muscle activity data was collected from four amateur and four pro golfers. Shear loads were high in both groups but were higher in the amateurs, averaging 596 Newtons of force vs. 329 Newtons in the pros. Compressive loading on the other hand was higher in the pros, averaging nearly 7,600 Newtons vs. 6,100 Newtons in the amateurs.

To put these compressive loads in perspective, consider that the swing of a pro golfer generates compressive forces around eight times his/her bodyweight and that of an amateur around six times bodyweight. Now consider that spinal compression forces in a runner are around three times body weight, and you can begin to appreciate the problem. It is also worth noting that cadaver studies have shown disc prolapse typically occurs with compressive loads of around 5,500 Newtons, which explains why the swing motion can increase the risk of an acute low back injury⁽¹⁵⁾.

Despite the risk of acute low back injury as a result of the swing, many golf players report a gradual and insidious onset of LBP rather than in a single event. Insidious LBP is thought to occur as a result of cumulative loading as a result of the combination of large magnitude spinal forces combined with a high frequency of swing repetitions. Studies show that elite golfers who consistently suffer LBP during golfing activities tend to have a higher frequency of swing repetitions (ie spend more time playing and practicing) than symptom-free golfers⁽¹⁶⁾. Cumulative loading also likely explains why elite players identify overuse rather than a traumatic event as the cause of their LBP⁽¹⁷⁾.

Asymmetry and LBP

As we can see in figure 1, a relatively slow backswing followed by a powerful downswing and follow-through produces an asymmetrical trunk rotational velocity, leading to differences in spinal loading patterns between the lead and trail sides of the lumbar spine. Indeed, studies show that LBP predominantly occurs on the trail side – ie the right side of a right-handed golfer and radiological investigations of elite players have demonstrated a significantly higher rate of arthritic change on the trail side of the vertebra of the spine than age-matched control subjects⁽¹¹⁾.

Other researchers have also noted that both left axial rotation velocity and right side-bending angles on the downswing reached peak values almost simultaneously and just after ball impact, coinciding with the point at which the majority of players in their study report experiencing LBP⁽¹⁸⁾. In plain English, a large amount of side bend angle combined with trunk rotation through the impact phase damages the lumbar spine by creating excessive intervertebral lateral shear (where the one vertebra move sideways relative to its neighbour). This shearing motion is potentially harmful since it is resisted primarily by disc strength rather than bone strength, thereby resulting in injury and pain, particularly on the trail side.

One way to reduce lateral shear is to decrease right-side bending (in a right-handed golfer). Studies show that players with LBP tend to address the ball with more spinal flexion - ie they slouch more and use more side-bend during the swing than healthy golfers⁽¹⁹⁾. The good news for golfers is that decreasing the amount of right side-bend on the downswing may be as simple as using better posture when setting up over the ball. It’s also important to note that the use of shorter clubs encourages right-side bending and that longer clubs may help in this respect.

The ‘X’ factor

In an effort to hit the ball harder and further, many golfers develop a pronounced backswing, which in theory at least allows more time for maximal force to be generated before ball contact. More backswing generates higher axial loading in the spine. This is especially the case during the initial stage of the downswing when the pelvis starts rotating towards the target a fraction before the shoulder. The idea is to generate the maximum ‘X’ factor stretch. A skilled player can increase this ‘X’ factor stretch by as much as 19% during the initial phase of the downswing.

The problem of course is that this additional stretch presents even higher loadings to the spine. An over-rotation (sometimes referred to as ‘supra-maximal twisting’) of the trunk while performing the golf swing increases the risk of spinal irritation and subsequent LBP. Moreover, many golfers are unable to replicate this degree of rotational stretch in the clinic when asked to do so from a neutral posture at a moderate speed. This has led some researchers to question whether the X-factor loading can be reduced.

One study found that reducing the relative amount of spinal rotation or torsion by increasing the range of hip turn during the backswing could help in cases of golfing-related LBP⁽²⁰⁾. In another study, researchers questioned whether an extreme backswing was even necessary⁽²¹⁾. The researchers investigated the effects of using a shortened backswing on ball-contact accuracy and club-head speed. The results showed that restricting the backswing by almost 20% (thereby reducing spinal loading) had no negative effect on overall swing performance.

Together, these and other results have led some researchers to suggest that golfers with LBP adopt a more ‘classic’ golf swing – as used in an earlier era of the game. The classic swing incorporates a reduced X factor, which decreases the torque and subsequent stress on the lumbar spine. This is achieved by allowing the lead heel (ie left heel in a right-handed golfer) to lift during the backswing to allow the pelvis (and not just the shoulders) to turn away from the target.

Getting to the core of it

Given the role of trunk musculature in generating the swing movement (both downswing and backswing), it’s unsurprising that researchers have investigated whether core muscle function (or dysfunction) is implicated in golf-related LBP. Some studies do indeed suggest that golfers with LBP appear to activate their trunk muscles differently to symptom-free golfers, and it’s possible that over time, these differences contribute to reduced trunk muscle strength and endurance.

For example, one study found that the onset times of major bursts of activity from some of the abdominal muscles were delayed in the golfers suffering LBP⁽²²⁾. In particular, the lead external oblique (left in right-handed golfers) was activated significantly later during the backswing in the golfers with LBP when compared to asymptomatic controls. Another study looked at EMG (muscle electrical activity) in the abdominal and trunk muscles of golfers with and without LBP, and found that highly skilled players tended to demonstrate reduced erector spinae activity at the top of the backswing and at ball impact⁽²³⁾.

A small number of studies have compared trunk muscle endurance in golfers with and without LBP. For example one study investigated the total time golfers with and without LBP could maintain an isometric transverse abdominis contraction and found that healthy golfers were able to maintain the static contraction for significantly longer than the golfers with LBP⁽²⁴⁾. This is relevant because transverse abdominis is known to be very important for protecting the lumbar spine by tensioning the connective tissue around it⁽²⁵⁾.

Another study found that static trunk extensor (eg erector spinae) holding times for golfers with LBP was significantly lower than values reported from healthy subjects⁽²⁶⁾, and an Australian study on trainee golf professionals found that golfers with a trail side (ie right side for a right-handed golfer) deficit of 12.5 seconds on the static side-bridge endurance test reported more frequent episodes of moderate to severe LBP⁽²⁷⁾. Further evidence indicates that elite golfers tend to have greater axial rotation strength in the direction they normally swing a golf club (ie to the left for a right-handed player) and that this asymmetry or imbalance is likely to be more pronounced in golfers with LBP⁽²⁸⁾. Together, these findings suggest that all golfers, but especially those prone to LBP should perform some regular core stabilization training exercise (see box 1).

Box 1: Core stabilisation training suggestions for golfers

Exercises that improve transverse abdominis and multifidus strength and endurance are especially recommended. Of particular importance is ensuring any side-to-side asymmetry is minimized – something that should be emphasized at all times.

Practical implications for athletes who play golf

If you’re an athlete who likes to indulge in a bit of golf – or indeed, if golf is your main sport - the key take home message is that because of the movement patterns and loadings involved, golf carries more injury risk than is generally realized, especially to the lower back. If you play golf and suffer back pain therefore, it’s more than likely that the regular practice of your sport will be a major contributing factor. To avoid this situation occurring – or even better, to prevent it – you will likely need to modify your training and playing habits, with a special emphasis on trunk strengthening using core training exercises. Below are some key recommendations on golf practice that can speed recovery and reduce the risk of re-injury:

·        Adopt a common sense approach to play/practice volume; while playing and practicing will improve your performance, you need to be aware of the spinal stresses that golf practice produces and find a balance between participation volume and recovery from LBP.

·        Address asymmetries in trunk musculature/strength between the lead and trail sides produced by high-volume, repetitive practice of golf swings. This means performing bilateral strengthening exercises and taking both left and right-handed practice swings.

·        Improve your trunk rotation flexibility, which helps control the relative over-rotation of the spine during the golf backswing. Make sure you lift your lead heel at the completion of the backswing, which allows more pelvic rotation, in turn reducing spinal torsion.

·        Improve the strength and endurance of your spinal stability muscles using a variety of core exercises.

·        Work on improving your hip rotation and range of movement, especially on the lead side. During the swing, the body pivots onto the lead side; a reduction in the amount of hip rotation on the lead side can cause increased movement and force to be transmitted to the lumbar spine resulting in LBP.

·        Always perform a thorough warm up prior to playing/practicing and rather than carrying your golf clubs on your shoulder, use a push cart, which is vastly preferable.

·        Last but not least, one of the best things you can do is seek professional assistance from a properly qualified golf coach to assess swing mechanics and determine if there is a need to decrease the amount of spinal side bend on the downswing and through impact. Improving posture over the ball is an example of the way this can be achieved.

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