Thursday 26 June 2014

What Biomechanical principles can be considered to maximise the distance of a Golf shot?


Introduction-
The game of golf in theory is a very simple and straight forward exercise, with a single aim of getting the ball into the hole using the minimum amount of shots possible. However this simplicity is what makes it so complex and competitive, placing a large importance on the distance a player is able to hit the ball and the accuracy in which they are able to do this. Having an understanding of the biomechanical principles behind the golf shot can give a player and coaches that extra accuracy and distance to beat the competition. This article will answer the question “What Biomechanical principles can be considered to maximise the distance of a Golf shot?”

The Biomechanical principles which will be explored in this blog will be:
  •          Angular velocity of the club head
  •        Length of arm-club system at impact
  •          Ground reaction forces
  •          Transfer of bodyweight
  •          Force summation
  •          Centre of gravity, ground forces
  •          Force and newtons laws of motion
  •          Torque and lever Arms

The information will be divided into sections starting at the basics and running through each part of the golf swing and the associated biomechanical principles:

Golf Swing
-Backswing
-Downswing

Maximising angular velocity of club head
-Force Summation
-Moment of inertia (Newtons first Law)
-Conservation of angular momentum (Newtons second law)

Maximise length of arm and club system at impact
-Torque and lever arms
-Change in momentum (Newtons second Law)

Ground reaction forces
-
Centre of Gravity
-Transfer of weight

Force Summation
The answer
How else we can use this information
References


Golf Swing
The first thing to consider with the understanding of the biomechanics behind increasing the distance of a players golf shot is to outline the correct technique and each section of the golf shot.  The shot has 4 main areas to consider they are the backswing, downswing, impact and follow through. The players grip and stance is also important to the action of the swing.



The above diagram shows the action of the golf swing from the beginning stage to the completion. This diagram shows where the range of movement begins to get you to understand how each part of the swing works in progression to build force which is applied to the ball. Likewise the below video shows the Tiger woods golf swing in slow motion. This video highlights a full range action from back swing to down swing, impact of the ball and follow through.



Maximising angular velocity of club head
Newtons first law (the law of Inertia) states that an object at rest or in motion will stay at rest or in motion unless a force is applied to it (Keogh, Reid and others, 2005). To simplify it into golf terms it means that the ball will stay stationary, on the tee or on the fairway, unless it is acted upon by a force, the golf club. However the ball does not stay in motion indefinitely because there are other forces acting on the ball, such as gravity, wind resistance and friction.  Once an object is moving its inertia can be then defined as it’s reluctance to change its state of motion, which is directly linked to the objects mass. A larger object has more inertia because in simple terms has more momentum, once the larger mass has started moving it is harder to stop compared with an object with a low mass which is easier to stop or change its direction. This is simple on a linear scale however when related back to Golf the angular motion inertia of the golf club, is directly “proportional to the objects mass and the square of the distance between the point of rotation and the centre of gravity of the object”.  The distance between the point of rotation and the centre of gravity of the object is also known as the radius of gyration(Keogh, Reid and others, 2005).

During a players back swing the golf clubs angular motion creates inertia as its mass is swung outwards away from the centre of the axis of rotation and the player’s centre of gravity (Blazevich, 2007). This idea of inertia is what allows the club to continue moving through its range of motion once it strikes the golf ball. Increasing the golf clubs inertia allows for a larger force to be applied to the golf ball as the resistance of the golf club to be slowed down during the impact is lower.  The back swing and down stroke are important then as there are two ways of increasing the inertia of the golf club, one increasing the mass the other is increasing the radius of gyration. By doubling the radius of gyration it quadruples the moment of inertia (moment describes any quantity multiplied by a distance). By increasing the radius of gyration the inertia of the club is increased which results in a larger force being transferred to the golf ball through the conservation of momentum (Newtons second Law).

The law of conservation of angular momentum in the golf swing as the speed of the hands in transferred from the hands to the head of the club. As the player begins the swing the hands are moving faster than the head of the club. However towards the end of the down stroke the hands begin to slow down and the difference in acceleration transfers the momentum from the hands to the head of the golf club accelerating and increasing the resultant velocity of the head of the golf club(Keogh, Reid and others, 2005). This increase in velocity is then transferred to the ball according to newtons second law of conservation of momentum and results in a higher initial velocity of the golf ball.

Maximise length of arm and club system at impact to increase torque
As a force is caused around a point for rotation it is called torque. For example you apply torque to a bolt when you loosen it, this force is in a rotational motion as the spanner moves around the axis of the bolt. Torque is important in the golf swing to maximise distance as the magnitude of the torque is the product of the force and the distance the force is being applied from the axis of rotation (Blazevich, 2007). Therefore we are able to increase the velocity of the ball by increasing the length of the lever which is hitting it (Arm and Club length).

Base of Support
A Golfers base of support is the key foundation for all movement associated with their swing. The base of support creates a stable base which the player’s centre of gravity is aligned with. The centre of gravity is an imagery line which passes vertically through the body and indicates the player’s centre of mass. A player’s balance is improved if there centre of gravity is located directly through the centre of their base of support, allows them to keep balance as weight is transferred to and from each foot and as the golf club is swung through the air.

As shown by the yellow line Adam Scott’s centre of gravity is placed directly between is base of support. Giving him the balance and stability needed to play a shot.  You can see from the photo the ball is placed forward of his centre of gravity however his stable base allows the player to keep their balance when playing the shot.

Force Summation
Force summation can be simplified to building up the force created by each part of the body starting at the larger segments such as the legs, hips and trunk, transferring it to the smaller parts of the body shoulders, arms and hands to produce a greater force than just one of the body parts (Blazevich, 2007). This principle can be used in golf as players can use the energy in the legs, hips and trunks to increase the force applied through the shoulders, arms and golf club to the golf ball. Increasing this force will increase the velocity of the club and ball, increasing the maximum distance achievable.

Ground reaction forces
The lower body plays also plays a role in the production of force within the golf shot. Increasing the players Ground reaction force can help to transfer the force created from the body to the ball. This transfer of force can be helped through the transfer of body weight. Loading the back foot during the back swing and transferring weight to the front foot as the club is moved through the down swing aligns the player’s momentum with the direction of intended direction of ball. The momentum being aligned with the direction of the flight of the ball increase the force applied to the ball.  

 The answer
In order to increase the maximum distance achievable of a golf shot the consideration of a range of biomechanical principles is vital. With the understanding of these principles and small adaptations it is possible to increase the length of a golf shot. But what do the principles mean and which ones are most important to increasing the distance someone is able to hit the ball? The answer comes down to which of these principles is going to achieve the highest force applied to the ball and give it the highest velocity. It all comes down to velocity and force the higher the force which is applied to the ball the higher the resultant velocity and the further the ball will go (assuming the projection of the ball is perfect).  So we could just saw lets swing the club faster, however we now have a biomechanical understanding that in order to swing the club faster and produce a higher force there are many different aspects to consider. Increasing the distance achievable with the ball you must consider each part of the body and how they work together, starting at the ground. The production of force begins with the base of support, then the transfer of body weight and force summation through the lower parts of the body, and the increasing of momentum and torque by maximising the range of motion through the swing and distance between the axis of rotation and the club head.  All of these factors play a part in increasing the force which acts on the ball increasing its distance.

How else we can use this information
This information can be used by coaches and teachers to aid students in increasing the distance of their golf shot but also to give them an understanding of how the body parts and the motion of the golf swing all ties in together. 

References
Blazevich, A. (2007). Sports biomechanics. 1st ed. London: A. & C. Black
Golf for Schools Program-Teacher Resource designed for Primary Schools. (2010). Golf Australia, Australian Sports Commission
Keogh, J., Reid, D. and others, (2005). The role of biomechanics in maximising distance and accuracy of golf shots. Sports Medicine, 35(5), pp.429--449.
Maddalozzo, G. (1987). SPORTS PERFORMANCE SERIES: An anatomical and biomechanical analysis of the full golf swing. Strength \& Conditioning Journal, 9(4), pp.6--9.