Golf Coaches’ Perceptions Of Key Technical Swing Parameters (P5)

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POSTURE

Fourteen coaches identified ‘Posture’ as a key technical parameter of the golf swing. Posture was typically discussed in terms of a golfer’s body position at set-up and their ability to control or maintain their posture throughout the swing.

On further clarification, two sub-categories of posture were identified: ‘Spine angle’ and ‘Postural Balance’. Spine angle often referred to the degree of ‘Forward Bend/Flexion’ of the trunk or spine to the pelvis and was viewed as a ‘Rotatory Axis’. For one coach Posture was defined as:

…having the correct amount of forward bend to the pelvis and torso, keeping the lumbar and thoracic as neutral as possible so bending forward from the hips, not so much from the knees, or rounded back. [Q8]

Typically, coaches observed a golfer’s Spine angle from a side on position whilst some also made reference to the degree of tilt in the upper torso, which was viewed from a front on position.

…it’s important to have good basic foundations from a set up point of view…good forward bends and good tilts…when we’re talking about tilt we’ll look at side bend, so looking at the golfer face [Q9]

It was considered important that golfers established and maintained their Spine angle from set-up throughout the swing to act as an axis, which the golfer could rotate around. Maintaining a stable Rotatory Axis was essential to creating powerful, efficient and consistent club motion and was sometimes valued above other key technical parameters such as the degree of body rotation. As one coach stated:

[The golfers] that are more efficient [and]…powerful are the guys that maintain a good centre and rotate around it…not necessarily making massive rotations…it’s about maintaining those postures…to reduce injury and to allow the club to get back to the golf ball more consistently. [Q10]

Often a loss in Spine angle towards impact was described as ‘Early Extension’ or ‘Hip Thrust’, which was linked to golfers with limited rotation through impact and was viewed as a detrimental movement in the swing.

Early extension has to do with rotation…you have a lot of people who come into impact and stop rotating so they’re not carrying the ball…they stop and stand up.[Q11]

The coaches also defined a golfer’s Posture as creating a balanced body position, which was categorised as ‘Postural Balance’.

[Posture is when the] body is in a balanced position that enables the club to get moving efficiently and effectively around the body…if somebody’s weight gets too much on the heels it’s…difficult to…get the correct pitch of the shoulders in the backswing. [Q12]

One coach defined Postural Balance statically at set-up as positioning the ‘Centre of Gravity’ correctly or creating balance points in a repeatable manner.

The reason for posture…is to develop the two key balance points…the sternum and belt buckle…getting the centre of gravity right and getting the balance points right…the key then is body motion…are you able to rotate. [Q13]

Some coaches referred to Postural Balance as tracing the golfer’s ‘Weight Transfer’ from set-up through the golf swing and having good interaction with the ground. A balanced set-up position allowed the golfer to be able to rotate more effectively with improved dynamic Postural Balance.

Balance…would be your most natural position at address where you…interact with the ground best and shouldn’t have to…make a compensation to create an athletic movement. [Q14]

If my hips, my chest, my arms, my hands move in the wrong order or out of posture, then I’ll be in poor dynamic balance and not really able to bring the power down or centre the strike. [Q15]

In contrast to the importance placed on posture by golf coaches it has received relatively little attention in the golf biomechanical literature. In the biomechanical literature, posture has been described in terms of the position of the body relative to the vertical, which shall be referred to as postural kinematics and includes variables such as trunk flexion and lateral bend. Hume et al.’s review of key biomechanical parameters of the golf swing, included establishing and maintain posture from set-up and throughout the swing. An optimal posture at set-up was defined as trunk flexed approximately 45º and tilted approximately 16º from the vertical and was deemed ideal for generating power and maintaining control during the golf swing. Chu et al. reported minimal change in the golfer’s trunk flexion from TB to IMP (~2 – 3°) and suggested that this angle should remain constant throughout the swing to allow the trunk rotation to be maintained on a plane. In contrast, McTeigue et al. claimed that trying to maintain constant trunk flexion could cause excessive lateral bending and backward bending at TB, which may cause injury.

Golf Coaches’ Perceptions Of Key Technical Swing Parameters (P5)An increase in trunk right side lateral bend (mean 8.6 ± 6.0º to 14.4 ± 6.5º) from Acc to IMP has been postulated to create an upward angle of the club path towards impact. An increased angle of the club path (i.e. attack angle) at IMP has been reported to positively influence driving distance. Chu et al. also suggested that trunk lateral bend should occur in a short period of time prior to IMP as early lateral bending could restrict trunk rotation. McTeigue et al. also commented on the greater increase in trunk right lateral bend angle towards IMP of tour players compared to amateur golfers. However, there were large differences (of approximately 16º) in the magnitude of trunk lateral bend angle at IMP to the values of Chu et al.

Postural kinematics have often been reported as 2D trunk angles obtained from motion analysis systems (e.g. angle between the vertical global axis and vector created between shoulder and pelvis markers) and electromagnetic systems based on a single rigid trunk segment. Differences in the methodologies including the trunk definitions used could explain differences in the magnitudes of postural kinematics reported in the literature.

Posture is also regarded as a dynamic variable of balance to prevent falling. Two independent measures are whole body centre of gravity (COG) (i.e. weighted average of the COG of each body segment in 3D space) and centre of pressure (COP) (i.e. the 2D point location in the horizontal plane where the resultant of all ground reaction forces act) [26]. The relationship between COG and COP measures have been used to investigate static and dynamic balance control [32]. In golf, Ball and Best [33] presented two distinct COP styles, ‘front foot’ and ‘reverse foot’, defined using the percentage of COP (%COP) between the front (i.e. foot closest to target = 0%) and back foot (i.e. foot furthest away from target = 100%). Front foot style was defined as a balanced position at TA (%COP ~ 57%), moving to the back foot in the backswing (%COP ~ 21%) then onto the front foot at IMP (%COP ~ 91%). The reverse foot style was characterised by players positioning COP towards the front foot in the early downswing (%COP ~ 61%) but then re-positioning COP towards midstance at IMP (%COP ~ 53%) and towards the back foot in the FT (%COP ~ 40%). No statistical differences were reported in clubhead velocity between front and reverse foot style golfers, but more recently differences in clubhead velocity within styles have been observed. Front foot style golfers with a greater range of COP movement and increased rate of COP movement to the front foot in the downswing were associated with higher clubhead velocity. Reverse foot golfers with higher clubhead velocity had COP measures near mid-stance and greater rate of COP towards the back foot at IMP.

The studies of Ball and Best do not account for COP between the toes and heel (i.e. anterior-posterior direction) or linked it to COG position, which could identify further balance control strategies. Burden et al. is the only study to report the COG path throughout the golf swing when using a driver. The COG displayed a consistent path across all right handed golfers in the backswing but there were differences in COG location at IMP. There was no clear reason given for this movement of COG and measures of performance, a golfer’s postural kinematics or COP were not measured.

In summary, the biomechanical definition of posture echoes the coaches description as the degree of forward bend and lateral bend in a golfer’s spine angle [Q8] and postural balance [Q12]. The golf coaches believed that maintaining a constant trunk angle throughout the swing, from TA through to IMP, would create consistent club position [Q10-11]. However, this perception cannot be fully supported by the literature as there are conflicting results and the pattern in trunk flexion throughout the whole swing has not been formally investigated. Previous studies have used ball velocity or clubhead velocity as measures of performance therefore the effect of trunk flexion on other measures of performance, such as shot accuracy and consistency, have not been fully investigated.

Trunk lateral bending was referred to by only a few coaches when discussing posture during the golf swing [Q9]. The contrasting literature, lack of performance related studies and minimal mention by coaches suggests that trunk lateral bend requires further investigation. Interestingly, the coaches alluded to the dependence of body rotations on posture [Q10], which is partially supported by the clinical study of Edmondston et al.

The coaches in the perception study also identified the importance of postural balance and discussed the idea in terms of positioning a golfer’s COG correctly [Q13] and their weight transfer [Q14], which echoes the biomechanical definition of static and dynamic balance. Often the coaches would make reference to a golfer’s postural kinematics as a means of creating a balanced position throughout the swing [Q16]. However, the relationship between COG, COP and postural kinematics has not been investigated in the literature.

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