Golf_Swing_Biomechanics

How has biomechanics contributed to the understanding of the golf swing' Introduction At the turn of the last century, there were 30,000 golf courses and 55 million people who played golf worldwide, whilst in the USA alone, the value of golf club memberships sold in the 1990s was $3.2 billion (Coleman and Rankin, 2005). Robertson (2003) states that the ‘Tiger Woods Phenomenon’ (the emergence of the officially ranked world number one golfer) has been one of the key factors in golf’s ever-increasing participation levels. However, Hocknell (2002) suggests that the rapid growth in prize money (particularly since the late 1980s) has been one of the principle factors. Hocknell argues that the modern day financial rewards have stimulated a greater level of professionalism amongst elite players. This in turn has created a higher standard of performance, thus generating a widespread interest due to the high levels of excitement, intensity and inspiration produced in the live events that are transmitted around the world. The debate regarding why golf has become so popular will no doubt continue, but whatever the argument may be, golf in the twenty first century, as a sport and as an industry, is continually growing on a global scale (Shmanske, 2000). Farraley et al (2003) discuss how golf’s dramatic rise in profile has significantly contributed to the increased employment of sports scientists within the industry. According to Schempp (2005), golfers of all abilities (especially professionals) are striving to gain an edge over their competitors, and will thus seek the assistance of sports scientists from a range of disciplines including psychology, biomechanics (not only in relation to the swing, but also equipment design), and exercise physiology and nutrition, in order maximise their performance. Schempp also states that the experts are continually publishing their research findings in discipline specific peer-reviewed journals. This should underpin the game of golf with the relevant and required scientific background that many feel it needs in order to develop. Elite professionals recognise that in order to be successful, a multidisciplinary perspective must be adopted (Ashwell, 2001). The meticulous approach of Tiger Woods with regards to his preparation and performance perhaps provides the perfect example of this theory. Diaz (1997) expresses how Woods sees himself as not just a golfer, but an athlete, who follows strict dietary habits and a regular cardiovascular and muscular exercise regime. Woods practices various performance enhancing techniques such as yoga and meditation, whilst also taking time to study swing biomechanics and practice golf psychology. Nonetheless, whilst Leadbetter (2004) recognises the benefits of this holistic approach (noting it as essential for success in the modern game), he suggests that golfers of all abilities would benefit enormously by firstly gaining some fundamental knowledge regarding swing biomechanics. Attempting to understand such a complex movement must involve the careful and considered analysis of its specific components (Egret et al, 2003). Biomechanists work with professionals and apply their specialised knowledge to each of the components with a goal of providing information to golfers who wish to produce maximum distance, accuracy, control and consistency in their golf shots. This essay aims to explore several of the key components within the golf swing that, over the last fifty years, have been of particular interest to biomechanists, whilst discussing how their research has contributed towards the understanding of the swing. Golf swing biomechanics – key components In relation to the golf swing, the last half century has been witness to a diversity of biomechanical investigations. Recent studies include Nesbitt et al’s (1996) analysis of different club head inertia tensors (the size of the ‘sweet spot’), Sprigings and Neal’s (2000) study on wrist torque, and Lindsay, Horton and Paley’s (2002) investigation of the trunk motion of male professional golfers. Hume, Keogh, and Reid (2005) mention several earlier studies (conducted in the 1960s and 70s) throughout their investigation into ‘The role of biomechanics in maximising distance and accuracy of golf shots’. They suggest that many of the studies on golf swing biomechanics have centred on two key components; namely the ‘cocking and uncocking of the wrists’ (in relation to the ‘swing plane’, which will be discussed later), and the forces of the feet – referred to as ‘ground reaction forces’ – responsible for driving the swing. Ground reaction forces Carlsoo (1967), Williams and Kavanagh (1983) and Hume, Kiogh and Reid (2005) all refer to the use of force plates (on which a golfer would stand) in their experiments to measure the ground forces throughout the golf swing. They all note that it is the interaction between the shoe and the ground that has been recognised as the vital link that allows a golfer to perform the body movements during the swing that lead to impact with the ball. This research suggested that the majority of high handicapped golfers (less skilled) do not shift their weight properly during the golf swing. High handicapped golfers often tended to move their weight onto their left side during the backswing (using the example of a right handed golfer, the opposite will apply for a left handed golfer), and transfer it onto their right side on the downswing. This improper technique is commonly referred to as the ‘reverse pivot’, and represents a significant reason why many, if not all high handicapped golfers do not hit the ball as far as they potentially could (Wallace, Grimshaw and Ashford, 1994). Cooper et al (1974), Burden, Grimshaw, and Wallace (1998) and Lindsay, Horton and Paley (2002) all suggest from their research that maximum force is generated in the down swing when weight is properly transferred from the right side to the left side (with correct timing). This is supported by Hume, Keogh, and Reid (2005), who state that a correct weight shift creates a gathering of momentum, since it is during this phase of the swing (downswing) that the physical power of the body is converted into the kinetic energy of the club head at impact. Swing plane The aforementioned ‘earlier’ studies, including Cochran and Stobbs (1968) and Budney and Bellow (1979), along with more recent studies by Pickering and Vickers (1999), Sprigings and Neal (2000) and Mitchell et al (2003), refer to the key components of the golf swing by using the ‘double pendulum’ model to describe the kinematic characteristics of the body. Cochran and Stobbs initially described this double pendulum as a model consisting of two levers. The ‘upper lever’ is formed by the golfer’s shoulders and arms, whilst the ‘lower lever’ corresponds to the club. The two levers are connected by a ‘hinge’ represented by the golfer’s hands and wrists. It is noted by Faralley et al (2003) that until the mid - 1980’s, the motion of a double pendulum was assumed to occur on a single plane during the downswing. However, technological advancements allowing three–dimensional filming and analysis techniques, provided Neal and Wilson (1985), and more recently, Coleman and Rankin (2005), with evidence contrary to the single plane theory. This research showed that the downswing can be, and is often, multi-planal. Meaning that a number of different swing planes (as well as different planes within one swing) can still produce repeatable good performance. Figure 1 provides an example of how the golf swing can start on different swing planes. Although Vijay Singh (world number 2, OWGR, 2006) does swing the club on two planes, he demonstrates a more ‘around’ take away (opposed to the more ‘up’ position of Toms). Singh swings the club around on a more natural arc. His arms are closer to his chest and have done nothing independent; they are simply following his body turn. Singh’s shoulder line represents a key characteristic of this type of swing; they are more parallel to the straight line, whereas Toms’s is closer to being parallel with the ground. Opposite, world number 7 David Toms (Official World Golf Ranking [OWGR], 2006) swings the club above plane (the path of the club relative to where it started - marked by the straight line). Toms keeps his arms more in front of his body throughout the swing and keeps the club working more ‘up’ than around. Figure 1: The golf swing started on two different planes (Quinton, 2005). Note: Figure 1 and the following illustrations have been included to give the reader a visual reference to the literature. They serve not only to aid explanation of the swing plane, but also as a reference point regarding a later area of discussion regarding wrist hinge and its role in creating club head velocity (p. 6). Transition Figure 2, A, illustrates two different transitions from the backswing into the downswing. With regards to swing plane, it is evident that the shaft of Toms’ club is still above and ‘off plane’, whereas Singh demonstrates a flatter, more ‘on plane’ position shaft is parallel to the line). From position A Singh simply rotates his body back to a very on plane impact position at impact, whereas Toms delivers the club above the natural plane at impact. As previously noted, swings that operate on different planes can still produce effective results. Nevertheless, Burden, Grimshaw and Wallace’s (1998) research suggested that the more a swing deviates from its natural plane, the more that a player (Toms) has to rely on their timing. Therefore this means that when a player’s timing is ‘off’, the consistency in relation to their ball flight, trajectory, distance and accuracy tends to suffer. A B Figure 2: Transition positions leading to impact Club head velocity (CHV) In basic terms, CHV can be described as the speed at which the club head travels through the impact area or ‘hitting zone’ (Sprigings and Mackenzie, 2002). This is the area in which, according to Pickering and Vickers, (1999) the club head should be travelling at its fastest during the swing so that maximum distance can be achieved. The key characteristics of a professional golfer’s swing demonstrated by Toms and Singh in Figure 2, A, represent, to a large extent, how to biomechanically gain maximum CHV. By observing Figure 2, A, although it offers a ‘down the line’ perspective, it is still possible to note how both Toms and Singh maintain a relatively narrow angle between their arms and the club shaft after initiating the downswing (compared to that of a mid- high handicapped golfer - see Figure 3). This element or ‘move’ in the golf swing is, according to Flick (1984), Sprigings and Neal (2000) and Sprigings and Mackenzie (2002) the key to storing energy and power, thus enabling the achievement of maximum CHV. To explain in more detail, the author will refer to Milburn’s (1982) study of segmental velocities (the speed at which the club head is travelling during different stages of the swing). Milburn’s experiment highlighted one of the key reasons why low handicapped amateurs and professionals are able to achieve maximum (or very close to, relative to their strength) CHV and mid-high handicapped amateurs are not. A) Mid-high handicap (M-HH) B) Low handicap/professional (LH/P) Figure 3: Comparison of club head positions just after the start of the downswing. Sprigings and Neal (2000) and Sprigings and Mackenzie (2002) refer to the Figure 3, B position as imperative for achieving the ‘late hit’, which, according to Pickering and Vickers, (1999) is an essential aspect of achieving maximum CHV. Figure 3, A provides an example of how M-HH golfers generally fail to achieve this late hit position, therefore relinquishing lots of their power early in the swing. Milburn tested this theory by timing the speed of the club head throughout different sections of the swing. By doing this he produced results that demonstrated how M-HH golfers had used up or ‘spent’ most of their power by the time that the club head had reached the ball. For example, the dotted line above each diagram represents where the club was at the top of the swing (the square represents the club head). Therefore, even though each person’s body had moved the same amount, in the same space of time, the M-HH player’s club head had travelled a lot further compared to the LH/P player’s club head, meaning that the M-HH golfer’s club head must have been moving significantly faster Sprigings and Mackenzie (2002) offer support to Milburn’s experiment by suggesting that club head velocity was found to increase (at the most critical time – impact) if the release is delayed (late hit). This theory resulted from their investigation into the energy supplied by the golfer during the swing, and in particular, its variation with the release angle (as seen in Figure 4). A) M-HH B) LH/P Figure 4: Release angle comparison Figure 4, B illustrates the delayed wrist action of a LH/P golfer compared to the ‘already released’ position of the M-HH golfer. According to Leadbetter (2004) position B involves a conscious effort from the golfer to hold back their wrist action (and consequently the club head), whereas the M-HH golfer will simply release the club naturally. This early, natural release was considered by Sprigings and Neal (2000) to be a considerable factor in relation to power loss and reduced CHV. At this juncture, the author would like to relate back to Leadbetter’s (2004) comments regarding the basic understanding of swing biomechanics (p.2, paragraph 3). It seems that golfers struggle to grasp concepts and swing ‘moves’ that feel ‘unnatural’ (relating to ‘holding on’ to the angle between arm and club shaft with increased wrist torque). Paradoxically, what immediately follows this ‘unnatural move’ is a completely ‘natural’ action as, towards the bottom of the swing arc, centrifugal force takes over and drives the club head through the impact zone without the need for any manipulation. According to Flick (1984) it is at this point when the club head should be released (often referred to as ‘snapping’ the wrists - unwinding the torque that has been stored in the wrists up to this point) in order to achieve maximum CHV. Conclusion This essay has examined how the appliance of sports biomechanics has enhanced the understanding of several components in the golf swing. It seems that certain elements of the golf swing, such as the swing plane, can significantly vary without a noteworthy shift in performance. However, the main point of discussion regarding wrist torque and the ‘late hit’, opposed to the early, ‘natural’ release of the club head, has served to inform the reader of the biomechanically correct technique that is required in order to generate maximum CHV, and as a result, maximum distance. In addition, this body of research could also serve to inform golf specific strength and conditioning programmes by observing the specific muscle groups that are used during the golf swing. Moreover, through a more detailed analysis of muscular-skeletal positions throughout the swing, biomechanists could also use the research that has been discussed in order to aid their understanding of injury prevention. Lindsay (2002) points out that this is an area in which research could and should be developed, as even though there has been some research into back pain (Sugaya et al., 1994) and wrist pain (Dalgleish et al., 2001) - two of the most common causes of referral amongst golfers, experts are yet to understand their aetiology and use that understanding to treat injuries most appropriately. Evidently, biomechanical analysis of the golf swing has attracted considerable research, however it seems as though the so called experts are still a long way from understanding the swing from a multidisciplinary perspective. This holistic approach is adopted by many of the world’s best golfers, with the aforementioned approach of Tiger Woods supporting this statement. Nonetheless, as Flick (1984) suggests, ‘The road to success is always under construction.’ It therefore seems that in order to attain an accurate understanding of the golf swing its entirety, it would be necessary to combine the research of not only bio mechanists, but exercise physiologists, physical therapists, psychologists….