Biomechanics
Understanding the factors that influence and govern human movement and sporting ability is essential to maximise performance. “Biomechanics focuses on the scientific principles of mechanics to understand movements and actions of the human body and sporting implements. Biomechanists study how various forces affect human motion and how movements can be improved in terms of efficiency and effectiveness” (Wuest & Bucher, p.222). Biomechanics as a field of study influences sport in terms of technique refinement and implement improvement to allow performance to reach greater levels than previously possible.
The Golf Drive Swing
“The objective of golf is to displace the ball from one position to another with the least number of shots possible. With the exception of putting, the initial passage of the ball through the air is generally responsible for a greater proportion of the displacement achieved” (Hay, p.276). Mastering the skill of driving results in long and accurate strokes which significantly shortens the distance of each hole. The golf drive swing contains many different biomechanical principles which when analysed can shed light on why different results occur during the drive. Left is a diagram in which Hay (1993) describes the basic biomechanical factors that influence the golf drive swing.
THE ANSWER
Technique (Biomechanics of the Player)
Set Up
Grip
There are three preferred grips used within the game of golf. The overlap, the interlock or the baseball grip (Video Below). These grips were analysed in a study by Walker (1964) which found that no one of the grips was found to statistically be superior to the others looking at distance and accuracy. Altering the positioning of the grip can also influence lever length which is discussed later in this blog.
Stance
The stance strongly influences the power and direction the golfer is able to achieve within the drive. The placement of the feet too close results in limited balance and loss of stability. A stance too wide results in inability to generate appropriate power through the legs and torso for the shot to achieve maximal distance. Hay (1993) recommends from a biomechanical standpoint that for maximal power to be achieved the feet should be placed slightly wider than shoulder width.
Another important part of the stance is the direction in which the feet are placed relative to the direction in which the shot is intended to go. The feet should be placed so that a line drawn perpendicular to the front of the feet is facing the direction in which the shot is intended.
Ground Reaction Forces
It is often thought that golf relies mainly on the upper body, but weight transfer and ground reaction forces contribute to the power during the swing. “In golf, loading the back foot during the backswing and transferring this weight onto the front foot during the downswing and acceleration phases can achieve a greater club-head velocity at impact” (Hume et al., p.435).
There are three preferred grips used within the game of golf. The overlap, the interlock or the baseball grip (Video Below). These grips were analysed in a study by Walker (1964) which found that no one of the grips was found to statistically be superior to the others looking at distance and accuracy. Altering the positioning of the grip can also influence lever length which is discussed later in this blog.
Stance
The stance strongly influences the power and direction the golfer is able to achieve within the drive. The placement of the feet too close results in limited balance and loss of stability. A stance too wide results in inability to generate appropriate power through the legs and torso for the shot to achieve maximal distance. Hay (1993) recommends from a biomechanical standpoint that for maximal power to be achieved the feet should be placed slightly wider than shoulder width.
Another important part of the stance is the direction in which the feet are placed relative to the direction in which the shot is intended to go. The feet should be placed so that a line drawn perpendicular to the front of the feet is facing the direction in which the shot is intended.
Ground Reaction Forces
It is often thought that golf relies mainly on the upper body, but weight transfer and ground reaction forces contribute to the power during the swing. “In golf, loading the back foot during the backswing and transferring this weight onto the front foot during the downswing and acceleration phases can achieve a greater club-head velocity at impact” (Hume et al., p.435).
The Swing
Backswing
“The backswing allows for energy to begin to be built and position the golfer in the optimum position for the downswing. The backswing begins with a simultaneous backward movement of the club head and the hands and rotation of the trunk to the right (Right Hander). As the combined backward movement of the hands and club and the rotation of the trunk continue, the left arm is raised and swung across the trunk, the wrists are cocked and the left forearm is rolled so that the back of the left hand lies in an approximately vertical plane” (Hay, p.285). The reasoning behind the rotation of the trunk and flexing of the wrists is to tension the abdominal muscles and tendons, shoulder muscles and tendons and wrist tendons to a point where the elastic energy is being created from their extension. “Tendons provide the majority of elastic energy savings. Isometric or eccentric contractions enhance force and further reduce energy cost. However, elastic savings is probably constrained by the need to reduce compliance for accurate control of position” (Biewener & Roberts, p.1).
“The backswing allows for energy to begin to be built and position the golfer in the optimum position for the downswing. The backswing begins with a simultaneous backward movement of the club head and the hands and rotation of the trunk to the right (Right Hander). As the combined backward movement of the hands and club and the rotation of the trunk continue, the left arm is raised and swung across the trunk, the wrists are cocked and the left forearm is rolled so that the back of the left hand lies in an approximately vertical plane” (Hay, p.285). The reasoning behind the rotation of the trunk and flexing of the wrists is to tension the abdominal muscles and tendons, shoulder muscles and tendons and wrist tendons to a point where the elastic energy is being created from their extension. “Tendons provide the majority of elastic energy savings. Isometric or eccentric contractions enhance force and further reduce energy cost. However, elastic savings is probably constrained by the need to reduce compliance for accurate control of position” (Biewener & Roberts, p.1).
Downswing
The elastic energy created through the backswing is released through the downswing. The objective of the downswing is to have the club head meet the ball at maximal speed and orientated in the correct direction. The downswing is initiated by the forward movement of the hips which Hay (1993) states begins 0.1 seconds before the top of the backswing is reached (Figure 11-5, Right). The arms begin their descent with the wrists still cocked until the left forearm reaches approximately horizontal when the wrists begin to unload so that when the club reaches impact the left forearm and club should be at 180 degrees (Image Below: Bottom Row, 2nd From Left ).
Impact/Strike Phase
The important features of the impact are the clubface orientation (figure 11-2) and the velocity at which the club head is moving. The club head should be level or just behind the hands at impact. The golfers centre of centre of gravity should be forward of the midline between the feet and the axis of the shoulders - arms - hands lever in the chest should be in the same position it was throughout the downswing.
Follow Through
The follow through is where the deceleration of the club and arms occurs to bring the implement that was accelerated to a halt. This process
dissipates the energy created in the downswing and uses many of the muscle groups of the backswing.
Summation of Force
It can be seen throughout the whole swing that the body is using many different muscle groups to create force to be exerted upon the ball. Hume (2005) defines that the summation of forces principle in that to maximise velocity of the most distal segment, the movement should start with the largest most proximal segments and move to the smaller more distal segments. This makes the golf swing a complex, coordinated activity that should commence with the larger proximal segments like the hips, trunk and legs and move to the distal segments of the upper arms, forearms and wrists. . Power generated throughout the legs and core progresses through the shoulders to forearms then snapped through wrists into club creating club head speed. The forward movement of the hips mid downswing and following phase of the downswing involving the trunks initial rotation and initial shoulder movement has been found by Hay (1993) to be responsible for around 1864 watts of the total 2337-2983 watts created by a good drive.
Torque
Torque is created throughout the golf drive swing by the twisting of the abdominal muscles and arms but can be strongly focused on within the wrists. This is the final point in which force can be applied to the lever before striking the ball. The optimal torque in a golf drive is found when a passive-active wrist technique is used, using both positive and negative torque. Negative torque is when the wrists are fully cocked at the top of the backswing and positive torque is uncocking during the downswing. Chen et al. (2007) found that using the passive-active wrist action provided an advantage in club head speed which translates to energy upon the ball. The image (below) highlights the cocking and uncocking of the wrists in the passive-active motion to create torque.
dissipates the energy created in the downswing and uses many of the muscle groups of the backswing.
Summation of Force
It can be seen throughout the whole swing that the body is using many different muscle groups to create force to be exerted upon the ball. Hume (2005) defines that the summation of forces principle in that to maximise velocity of the most distal segment, the movement should start with the largest most proximal segments and move to the smaller more distal segments. This makes the golf swing a complex, coordinated activity that should commence with the larger proximal segments like the hips, trunk and legs and move to the distal segments of the upper arms, forearms and wrists. . Power generated throughout the legs and core progresses through the shoulders to forearms then snapped through wrists into club creating club head speed. The forward movement of the hips mid downswing and following phase of the downswing involving the trunks initial rotation and initial shoulder movement has been found by Hay (1993) to be responsible for around 1864 watts of the total 2337-2983 watts created by a good drive.
Torque
Torque is created throughout the golf drive swing by the twisting of the abdominal muscles and arms but can be strongly focused on within the wrists. This is the final point in which force can be applied to the lever before striking the ball. The optimal torque in a golf drive is found when a passive-active wrist technique is used, using both positive and negative torque. Negative torque is when the wrists are fully cocked at the top of the backswing and positive torque is uncocking during the downswing. Chen et al. (2007) found that using the passive-active wrist action provided an advantage in club head speed which translates to energy upon the ball. The image (below) highlights the cocking and uncocking of the wrists in the passive-active motion to create torque.
Biomechanics Of Equipment
Coefficient of Restitution
To be successful at golf players must transfer energy from the club head to the ball efficiently. The coefficient of restitution, as described by Blazevich (2010) refers to the proportion of energy that remains with colliding objects after collision. The coefficient of restitution is hard to control as clubs and balls have limited variance but understanding it may help in club and ball selection. Restitution is the ability of the ball to return to its natural state with minimal energy loss. Choosing a ball with a high coefficient of restitution will result in the ball gaining more energy. Also a club with a larger surface area and weight will allow for increased power to be imparted upon the ball. (Figure 11.2)
Levers
Lever length strongly influences the distance the ball is able to be hit. Holding the club high on the grip causes lever length to be maximised (Figure 2.3). It can also be noted that the left and right arms are at full extension when the ball is struck. This is to maximise the length of the lever and increase total speed at the end of the lever. A study by Kenny et al. (2008) found that club length was found to have statistically significant effect on both club head and ball velocity. Although club length is limited, using the longest legal club, and creating the longest possible lever arm around the centre axis will achieve longer shots. The study by Kenny et al. (2008) also found that increased shaft and lever length did not impact accuracy adversely. "A common recommendation for technical correction is maintaining a single fixed centre hub of rotation with a two-lever one-hinge moment arm to impart force on the ball" (Hume et al. p.429). The arms and body rotate around the centre of the chest which remains in the same spot throughout the swing (Fig 11-4). This is too maintain balance and control over the shot.
The Magnus Effect
The magnus effect can have both positive and negative uses within golf. The magnus effect as described by Blazevich (2010) is that a spinning ball grabs the air that flows past it due to friction between the air and the ball, this causes the air on one side of the ball to be moving faster and the other side to move slower (Fig 16. 1). This allows pressure to be higher on one side of the ball than the other causing the ball to move towards the low pressure.
It can be seen (figure 16.2) that the way the club strikes
the ball imparts spin on the ball. If the ball has side spin imparted on it will swerve in the direction the club was angled at impact. To avoid imparting sidespin on the ball the club must impact the ball perfectly square to the target and the direction of the stance (Figure 16.2).
If backspin is imparted upon the ball it will travel further through the air due to the low pressure being created above the ball and the high pressure below (Refer to figure 16.1). "Golf drivers are designed with a backwards-angled clubface, to impart a backward spin on the ball to increase hitting distance" (Blazevich, p. 194).
It can be seen (figure 16.2) that the way the club strikes
the ball imparts spin on the ball. If the ball has side spin imparted on it will swerve in the direction the club was angled at impact. To avoid imparting sidespin on the ball the club must impact the ball perfectly square to the target and the direction of the stance (Figure 16.2).
If backspin is imparted upon the ball it will travel further through the air due to the low pressure being created above the ball and the high pressure below (Refer to figure 16.1). "Golf drivers are designed with a backwards-angled clubface, to impart a backward spin on the ball to increase hitting distance" (Blazevich, p. 194).
The Result
Once the optimal swing technique and equipment is used the golf drive should be the longest shot able to be hit by the golfer. The key biomechanics to remember when trying to achieve optimal power and accuracy in the golf drive swing are:
· A stable stance with your feet about shoulder width apart. Stability allows control over the swing which contributes to the accuracy of the shot.
· A stable upper chest throughout swing as this acts as an axis point for rotation during the drive.
· A grip high on the club to allow maximal length of the lever. Also arms and wrists at full extension during strike phase to maximise lever length and club head velocity.
· A ball with the highest coefficient of restitution to maximise energy imparted from the club to the ball.
· Understanding how the magnus effect imparts lift upon the ball and can be used to get the ball to curve around obstacles.
· Maximising torque in the wrists throughout the swing using the passive-active wrist cocking techniques to increase club head velocity.
· Maximising ground reaction forces by transfering weight onto the back foot during the backswing and onto the front foot during the downswing.
· Maximal speed of release. The greater the club head velocity at strike phase, the greater the energy imparted on the ball.
· Summation of forces throughout the swing using the hips, wrists, rotation etc.
As the following video highlights, Tiger Woods has been able to maximise the use of biomechanical principles to create consistently long and accurate drives.
· A stable stance with your feet about shoulder width apart. Stability allows control over the swing which contributes to the accuracy of the shot.
· A stable upper chest throughout swing as this acts as an axis point for rotation during the drive.
· A grip high on the club to allow maximal length of the lever. Also arms and wrists at full extension during strike phase to maximise lever length and club head velocity.
· A ball with the highest coefficient of restitution to maximise energy imparted from the club to the ball.
· Understanding how the magnus effect imparts lift upon the ball and can be used to get the ball to curve around obstacles.
· Maximising torque in the wrists throughout the swing using the passive-active wrist cocking techniques to increase club head velocity.
· Maximising ground reaction forces by transfering weight onto the back foot during the backswing and onto the front foot during the downswing.
· Maximal speed of release. The greater the club head velocity at strike phase, the greater the energy imparted on the ball.
· Summation of forces throughout the swing using the hips, wrists, rotation etc.
As the following video highlights, Tiger Woods has been able to maximise the use of biomechanical principles to create consistently long and accurate drives.
How Else Can We Use This Information
Understanding the biomechanics involved in maximising the power and accuracy of the golf drive swing allows people to gain transferable knowledge that can be imparted into many sporting fields which require the use of levers, force summation or are affected by the magnus effect.
Understanding that maximising lever length allows for greater club head velocity can be transferred to sports such as cricket, baseball and tennis. Within cricket in the scenario you need to hit a six to win the game it can be understood that maximising lever length can allow for greater velocity of the bat which will impart more energy upon the ball to make it travel further. Conversely, "a pitcher in baseball or softball could use this information to cramp up their opponent" (Blazevich, p.22) not allowing maximal lever length to be achieved.
The concept of the magnus effect can be transferred to the sport of tennis to understand how to create swing serves by imparting sidespin on the ball. It also allows players to maximise the power imparted on shots by understanding how top spin allows the ball to drop quicker than usual making shots land shorter than originally possible. It also can be used in other sports, "soccer players kick across the ball to put spin on it to curve around a wall of players at a free kick" (Blazevich, p. 193).
Biomechanical principles are similar throughout many sports even if the procedures and uses are slightly different the blanket principles still apply. Understanding how to use these principles to your favour allow for maximised performance.
Understanding that maximising lever length allows for greater club head velocity can be transferred to sports such as cricket, baseball and tennis. Within cricket in the scenario you need to hit a six to win the game it can be understood that maximising lever length can allow for greater velocity of the bat which will impart more energy upon the ball to make it travel further. Conversely, "a pitcher in baseball or softball could use this information to cramp up their opponent" (Blazevich, p.22) not allowing maximal lever length to be achieved.
The concept of the magnus effect can be transferred to the sport of tennis to understand how to create swing serves by imparting sidespin on the ball. It also allows players to maximise the power imparted on shots by understanding how top spin allows the ball to drop quicker than usual making shots land shorter than originally possible. It also can be used in other sports, "soccer players kick across the ball to put spin on it to curve around a wall of players at a free kick" (Blazevich, p. 193).
Biomechanical principles are similar throughout many sports even if the procedures and uses are slightly different the blanket principles still apply. Understanding how to use these principles to your favour allow for maximised performance.