Thomas Clayton

Clay0079 - 2121668

Driving off the tee

The golf swing is a complex whole body movement that uses the summation of momentum principle, to create high endpoint velocity and maximum distance. (Bradshaw, Keogh, Hume, Maulder, & Nortje, 2009) Although golf is played by players with large variances in physical characteristics and technical ability the biomechanical principals behind the optimisation of distance and accuracy remain the same. Biomechanics has a role in maximising the distance and accuracy of golf shots by providing both qualitative and quantitative evidence of body angles, joint forces and muscle activity patterns. ( Hume, Keogh, & Reid, 2005) The golf swing is an example of a throw-like pattern where the kinetic chain incorporates most segments of the body; with the rotation of the body preceding rapid arm swing. (Blazevich, 2007)

Significant biomechanical principals discussed include: newtons three laws, inertia, velocity, angular and linear velocity, torque, summation of forces, projectile momentum and the kinetic chain.

Major Question

What are the optimal biomechanical techniques for maximising driver distance and accuracy off the tee?

The answer

When analysing the golf drive biomechanically the swing can be broken down into five distinct phases. These phases include: the address, back swing, top of back swing and beginning of down swing, downswing and contact and follow through.

Address

The address refers to the static position the golfer is in before they play the shot, optimal biomechanical positioning should align the golfer to the target, establish dynamic and static balance and provide the optimal shaft angel and grip on the club. In preparation for the dynamic movement of the swing the golfer’s legs should be slightly bent and pushed firmly into the ground, preparing to counter act the ground reaction force and Newtons third law of equal and opposite reaction. (Blazevich, 2007) As seen in the figure 1, the ball should be placed at the heel of the front leg promoting a neutral shaft position and a positive weight distribution towards the back leg of 50% to 60%. ( Hume, Keogh, & Reid, 2005) When driving for optimal distance as seen in figure 2, a stance referred to as the reverse K stance is considered optimal. This is the case as the reverse k made by the trailing hip moving slightly forward allows the trailing hip to produce increased torque, resulting in greater acceleration and swing speed. In addition to the shift in the trailing hip the tilt the stance creates is also important as it encourages a shallower angle of attack on the downswing, resulting in an increase in club head speed. 

Figure 1. Optimal address

Figure 2. Reverse k stance

Back Swing

The golf swing consists of 3 parallel points pivotal to both force creation and accuracy, these include: parallel point 1, consisting of the club shaft being parallel to the ground at the beginning of the back swing (figure 3), parallel point 2, when the front arm is parallel to the ground (figure 4) and parallel point 3 related to parallel point 1 but on the downswing. The primary role of the back swing is to provide a base link for the kinetic chain and to prepare the muscles for force preduction in the downswing. ( Hume, Keogh, & Reid, 2005) As the golfer begins to rotate in the back swing torque, defined as Force X distance is delivered in an up down process. (Blazevich, 2007) From the commencement of the back swing through to parallel point 1 a one piece take away is considered optimal. As seen in figure 5 a one piece take away refers to maintaining the triangle formed by the two arms and the chest through to the end of the takeaway period at parallel point 1. Chua, Sella, & Lepha, 2010 found that the delayed release of the club and increased back swing angle created from the one piece takeaway increased torque applied at the mid-point of the shoulders resulting in improved club rotation and an increase in club head velocity. As mentioned in the address phase, the reverse k stance allows the golfers weight to shifted laterally onto to the back foot as the range of hip rotation is increased as the left hip turns the pelvis away from the target resulting in the arc of the swing being flattened. (Maddalozzo, 1987)

Figure 3. Parallel point 1

Figure 4. One piece take away

Figure 5. Parallel point 2

Top of back swing and beginning of down swing

In terms of force production the top of the back swing and the beginning of the downswing is the most crucial point of the golf swing, through a point known in golf as the X factor. The X factor refers to the maximisation of the hip and shoulder angle, resulting in increased rotational velocity and increased club head speed. Figure 6 outlines the correlation between x factor stretch (shoulder rotation - hip rotation) and swing speed, reviling that golfers should focus on creating separation between backward rotation of the upper torso and pelvis. (Chua, Sella, & Lepha, 2010) In addition to shoulder rotation research has reviled the benefit of left knee flexion for right handed golfers at the top of the back swing, with results indicating that for every one standard deviation increase in leading knee flexion angle, ball velocity increased 0.203 standard deviations. (Chua, Sella, & Lepha, 2010) In order to maximise distance at this stage of the swing considerable ground reaction forces should be produced as the body weight is transferred from the back foot to the front during the downswing. Optimal performance results in the effective utilisation of momentum generated by bodily movements during the golf swing. ( Hume, Keogh, & Reid, 2005)

Figure 6. X factor stretch

Downswing

The purpose of the downswing is to return the club head through the slot angle at the maximum velocity. Preceding the X factor the golfer vigorously releases and rotates forward, as the body weight is shifted to the leading foot, bringing the club head to the ball in 0.30 to 0.06 tenths of a second.  Figure 7 highlights the slot angle created from the position of the shaft at address and the position of the shaft at parallel point 2, figure 8 demonstrates the optimal downswing through the centre of the slot angle. As the golf swing is a throw like movement the kinetic chain in the downswing works sequentially in a bottom up process as the swing progresses from the legs, through the hips, lower back, upper back, shoulders, arms, and then wrists. ( Nesbit & Serrano, 2005) When performed optimally summation of forces is in play as the amount of kinetic energy is greater than the sum of the parts. ( Hume, Keogh, & Reid, 2005) As the club travels from parallel point 3 to impact and the wrists unlock, the torque components rapidly decrease as the wrists cannot keep up with the rotational speed of the club at contact, resulting in all torque components working negatively. It is at this point that the wrists transition into a free hinge arrangement as the golfer simply holds on to the club as its momentum carries it to impact. In an example of Newtons 3^rd law, as the wrists begin to work negatively the straightening of the shaft continues to accelerate the club head resulting in club head velocity peaking precisely at impact. ( Nesbit & Serrano, 2005)

Figure 7. Slot angle 

Figure 8. Downswing through the slot angle

Contact and follow through

As the club comes through the slot angle during the downswing not just velocity is important but also club face angle leading into contact. As Newton's laws of motion predict during the golf swing significant correlations are apparent between club head speed and total work, with total work being classified as the ability to apply forces and torques in the direction of motion during the downswing. Optimal performance results in higher total work and the point of impact. As mentioned in the down swing it’s at this time that arms take over from the wrists, pulling inwards and decreasing the distance from the club to the upper torso, increasing acceleration (figure 9). (Hellstrom, 2009) During impact the club face and the ball produces torque that can twist the club face if the sweet spot of the club doesn’t make contact with the ball, resulting in the ball loosing accuracy. When driving off the tee the golfer can take advantage of moment of inertia, to counter act the torque of the contact. Moment of inertia refers to the resistance an object has to torque. (Blazevich, 2007) In order to eliminate excess torque golfers need to strike the ball where the moment of inertia is largest, referred to as the sweet spot. After contact is made with the ball and Newtons Third Law has occurred the golfer continues on the designated swing path as the body decelerates the club head by using eccentric muscle actions. The golfer should finish in a balanced position with the trunk facing the target with the hips and left angle rotating to absorb the weight transferal. ( Hume, Keogh, & Reid, 2005)

Figure 9. Decrease of club distance

Looking at Newtons Second Law: ‘the acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of the object’. (Blazevich, 2007)  Using the club speed produced during the previous phases of the swing, the subsequent ball speed and impact time of the club on the ball can be used to work out the acceleration and force required to move the ball at that speed.

F= ma

Change in acceleration / collision time = ball acceleration X the mass of the ball

For the sake of these calculations the ball will be taking off at 283kph or 78.7 metres per second, approximately 1 and a half times the club speed at impact with a contact time of 0.0005 seconds and golf ball mass of .0459kg.

78.7 m/s               /              .0005   

 

=             157,400 m/s/s

157,400 X .0459   

             

=             7224.66n or 736.710kg

How can we use this information?

In terms of the game of golf this information can be used to educated golfers of any level on the optimal biomechanical principals for maximising distance and accuracy when driving off the tee. The breakdown of the swing into the 5 phases: the address, back swing, top of back swing and beginning of down swing, downswing and contact and follow through, outlines optimal technique and a detailed understanding of how and why each technique is considered optimal. An increased understanding of the swing mechanics and the creation of increased swing velocity will also allow golfers to tailor the angle of attack and loft of the club to suit their swing and corresponding swing speed, maximising distance. As seen in figures 10 and 11 the importance of the correct loft and spin on projectile motion cannot be understated, as too much loft and a fast swing speed will result in the angle of the projectile being too high while not enough loft and slow swing speed will result in the projectile angle being too flat. The information can also be used by various golfing associations such as the USPGA in areas such as course creation and rules and regulations for golfing equipment, such as driver shafts and club faces, to ensure all equipment  and technological innovations are within acceptable limits.

Figure 10. Swing speed to driver loft

Figure 11. Golf Driver Loft and Max Distance

In terms of other applications the biomechanical principals outlined could be transferred to any sport with a throw-like pattern where the kinetic chain incorporates segments of the body sequentially, including: cricket and baseball batting, hockey, tennis etc. All other biomechanical principals analysed throughout the blog, such as Newtons Laws also have firm groundings in all other sports and skilled movement patterns.

References

Hume, P., Keogh, J., & Reid, D. (2005). The Role of Biomechanics in Maximising Distance and Accuracy of Golf Shots. Sports Medicine, 429-449.

Nesbit, S., & Serrano, M. (2005). Work and Power Analysis of the Golf Swing. Sport Science and Medicine, 520-533.

Blazevich, A. (2007). Sports Biomechanics, The Basics: Optimising Human Perfromance. London: A&C Black Publishers.

Bradshaw, Keogh, Hume, Maulder, & Nortje. (2009). The Effect of Biological Movement Variability on the Performance of the Golf Swing in High- and Low-Handicapped Players. Research quarterly for exercise and sport, 185-196.

Chua, Y., Sella, T., & Lepha, S. (2010). The relationship between biomechanical variables and driving performance during the golf swing. Journal of Sports Sciences, 1251-1259.
Hellstrom, J. (2009). Competitive elite golf: a review of the relationships between playing results, technique and physique. Sports Medicine, 723-732.

Maddalozzo, J. (1987). An anatomical and biomechanical analysis of the full golf swing. NSCA Journal, 74-79.

Miura, K. (2001). Parametric acceleration ± the effect of inward pull. Sports Engineering, 75-86.

Figure 1. Golf - How bomb your driver. Me and my golf, Proudman and Ward, 2014. https://www.youtube.com/channel/UCTwywdg9Sw5xs4wdN-qz7yw

Figure 2. Golf - How bomb your driver. Me and my golf, Proudman and Ward, 2014. https://www.youtube.com/channel/UCTwywdg9Sw5xs4wdN-qz7yw

Figure 3. How to hit your driver dead straight. Me and my golf, Proudman and Ward, 2015. https://www.youtube.com/watch?v=oXpppIiEEZQ

Figure 5. How to hit your driver dead straight. Me and my golf, Proudman and Ward, 2015. https://www.youtube.com/watch?v=oXpppIiEEZQ

Figure 4. Perfect golf swing review. Backswing Chapter, Mann. J, 2007. http://perfectgolfswingreview.net/backswing.htm

Figure 6. Perfect golf swing review. Backswing Chapter, Mann. J, 2007. http://perfectgolfswingreview.net/backswing.htm

Figure 7. Nail your driver straight. Me and my golf, Proudman and Ward, 2014. https://www.youtube.com/watch?v=R81ZMI4V_bw

Figure 8. Nail your driver straight. Me and my golf, Proudman and Ward, 2014. https://www.youtube.com/watch?v=R81ZMI4V_bw

Figure 9. Parametric acceleration ± the effect of inward pull. Sports Engineering, Miura. K, 2001.

Figure 10. Malaysia's Golfing Commonity. My Golf.com. 2008. http://www.mygolf.com.my/phpbb2/viewtopic.php?t=10404&sid=1585b1a988ee120e2ca3859cfdeb2e82

Figure 11. Golf Driver Loft and Max Distance. Instant Golf Lesson, Cotter. R. 2015. http://www.instantgolflesson.com/golf-driver-loft-for-max-distance.php