The drive is the launching stroke used off
the tee when playing a hole of golf. While distance is important for other strokes
as well, the drive sets up how far the following shots need to be hit in order for
the ball to reach the green, so it is important to know how to drive as far as
possible to save playing unneeded shots later on the hole.
There are a number of biomechanical factors
that can affect the distance a golf ball travels; some of which the player has
control over, and others that are external factors that the player cannot
control. The personal aspects must all be performed explicitly in order to
achieve optimal distance and accuracy. Environmental constraints may affect
ball flight once the ball has been hit, such as wind, rain, and temperature, as
well as other principles such as aerodynamics, drag and spin.
The golfer’s swing must be performed as a
whole ‘fluid’ movement, and follows a throw-like
movement pattern using kinetic sequencing; where the combination of the
body rotation, arm swing and follow through will increase the kinetic energy
that the body produces (Blazevich, 2012), transferring that onto the golf ball.
It is therefore important that the player has good grounding with his/ her legs
and feet for stability and balance in order to get the initial force behind the
shot.
There are four phases to the golf drive;
(1) the setup (or preparation), (2) the backswing, (3) the downswing, and (4)
the follow-through phase (Hume, Keogh, & Reid, 2005).
THE SETUP (PREPARATION) PHASE
As mentioned previously, balance and
stability are very important as a base support, as a lot of power is initiated
from the legs, and the player’s centre of balance must be stable in order to
rotate effectively. Goehl (2002) states that it is “almost impossible to have a
good swing without a good stance”, and that the player’s feet should be about
shoulder width apart (although this is variable) with slight flexion in the
knees to enhance balance. The larger the area of base support, the more stable
the golfer is, however if it becomes too large, it can restrict movement
(Blazevich, 2008). Weight distribution begins centred, and evenly balanced
between heels and toes, however during the backswing the majority of weight
should be on the back leg to support where the club is as the body rotates. Bending
at the knees, and transferring the majority of the weight to the back leg also engages
ground reaction force (GRF), which demonstrates Newton’s third law that for every action, there is an equal and
opposite reaction (Blazevich, 2008, p. 43), allowing the player to push off
the ground to get more force in the strike.
Correct posture is important to maintain
throughout the shot to ensure injuries do not occur to the lumbar spine (Free
Online Golf Tips, 2014), that is not designed for rotation. The twisting action
should be located in the thoratic spine (mid-back) (Foley & Kaspriske,
2010), which is the central point of rotation, with the body only bending at
the hips, not through the back.
When setting up the shot, the ball should
be placed on a tee (about ¾ of the way up the club face in height when the club
is resting on the ground), in line with the inside heel of the front foot, and
far enough in front of the player that it is at the end of the club shaft when
the player is standing relaxed in the “contact” stage. The aim is to hit the
ball in the centre of the clubface (the “sweet spot”) for maximum drive
distance (Smith, 2000). Lining the shot up accurately before the backswing means
that the only thing the player needs to worry about is executing the correct
body movement in the swing.
THE BACKSWING AND DOWNSWING PHASES
As the backswing and the downswing phases
contain similar movements, we will look at the biomechanical factors that are
associated with both of them together.
As mentioned previously, the golf swing is
a brilliant example of a throw-like
movement pattern, where a summation of forces occurs throughout the body,
starting at the proximal body parts, and continuing to the distal segments
(Blazevich, 2008, p. 186). In the case of golf, the accumulated forces are further
transferred through the hands and fingers to the club, and then transferred
onto the ball. This kinetic sequencing allows the player to build up much more
force to hit the ball with than if they simply tapped the ball with a flick of
the wrists (Blazevich, 2012). Hume, et al. (2005) suggest that if the swing is executed
correctly, the amount of kinetic energy is greater than the sum of the parts.
The kinetic chain starts with the feet
pushing into the ground. Newton’s third law states that for every action, there is an equal and opposite reaction
(Blazevich, 2008, p. 43), so when the feet push into the earth, the ground
exerts an opposing force, called the ground reaction force (GRF) (Blazevich,
2008, p. 43). This starts the summation of forces, and gives the lower body
power that is transferred to the hips and torso, then continues to the elbows,
wrist acceleration, and through the hands and fingers to the club (Hume, et al.,
2005). A study done by Chu, Sell and Lephart (2010) showed that greater
vertical ground reaction force of the leading foot at the beginning of the
downswing indicated greater weight shifting forward, and resulted in more force
being transferred to the ball. Finally, the momentum is transferred to the golf
ball, that when hit in the correct place on the face of the club, at the
correct angle, will travel to the target destination.
As the ball is struck, the body’s weight
should be transferred to the front leg. By transferring the weight at that
point, it can generate a greater club head velocity at ball impact (Hume, et
al., 2005). The club head is the only thing that makes direct contact with the
ball, so if the club head velocity is high, then there is also a high amount of
energy transferred to the golf ball, helping it to fly further. This follows
Newton’s 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, 2008, p. 43). Almost
every aspect of a golfer’s personal swing style affects the club head velocity,
so it is paramount to get the kinetic sequence functioning effectively, as it
has been proven that when the summation of forces is at its strongest, maximum club-head speed is achieved (Hume et al., 2005). Bradshaw,
et al. (2009) proved that club head velocity was linearly related to shot success,
and Hume et al. (2005) found that the major contribution to club head velocity
was the angle and movement of the wrists.
Momentum of the ball is determined by
its mass multiplied by the velocity put upon it, and because in
golf the mass of the ball does not change, the only way to increase momentum is
to increase the velocity through the ball (Hume et al., 2005), hence aiming to
achieve maximum club-head velocity.
Hitting the ball in the centre of the
club (called the sweet spot) is vital
to ensure that the ball receives the maximum amount of force possible from the
kinetic energy summation in order to travel the furthest distance (Smith,
2000).
As the club is an extension of the
forearms, it acts as a third class lever that produces more force due to the
downswing; the driver being the longest club therefore produces the most force
of all the clubs (according to the principal of leverages), increasing the
velocity that can be achieved (Beck, 2013; Baldwin, 2013).
