What are the biomechanics behind an effective hockey slap hit?
INTRODUCTION:
Hockey in the last 20 years has been one of Australia’s most
dominant sports and with the recent success of the Hockeyroos finishing second
at the World Cup and the Kookaburras taking the title for the second World Cup
in a row, we can see that the sport is developing within Australia once again.
With the Commonwealth and Olympic Games just around the corner, teams around
the world are looking at continuously developing their game to improve and be
the best they can be. Many teams are looking at developing their passing game
more then focusing on individual skills to beat other teams. One of the main
ways to pass the ball to other teammates is through a slap hit. Using a slap
hit can deliver the ball at high speeds and can also be used to deceive
opposition players. In the following paper, we discuss the main principles of
biomechanics involved in the hockey slap hit that can assist in improving the
speed, accuracy, and efficiency of the pass.
THE SLAP HIT
As you can see from the video above, the slap hit is a skill that
can be broken down into three phases: Preparatory, Contact and Release, and Follow
Through. When preparing for the slap hit, players generally have a front on position
with their body. The ball is level with the left foot, with the left foot
facing the ball. The positioning of the ball is not critical and will vary from
player to player but can be a factor in how effective the skill is performed.
The body is low to the ground, with the left leg used as the leading leg
throughout the skill. The back knee (right leg) is almost touching the ground,
as the left leg steps towards the ball. The final thing during the preparatory
phase is hand positioning. Like the positioning of the ball, it will vary from
player to player. For optimal performance through the skill, the hands on the
stick should be placed together at the top of the stick (Hockey SA, 2014).
Following the preparatory phase is the Contact and Release phase. Throughout
this phase, players are using momentum that has begun in the preparatory phase
to make contact with the ball. The right knee stays close to the ground; with
the left leg acting as a stabiliser for the rest of the body and the body of
the player gradually becomes lower to the ground. The stick connects with the
ball, which should be in reach to create a stable environment for the body. The
rotation of the body is critical to continue the momentum of the movement going
through to the ball and on to the follow through phase. The follow through is
the final phase of the slap hit and is the last critical component of the skill.
In order to finish the skill effectively, the individual should maintain low
body position to keep their balance. The stick should rotate around the body
after the ball has been released for a greater chance of the pass being
accurate (Hockey SA, 2014).
After discussing the three phases of the slap hit, we can
determine what biomechanics principles should be addressed in order to perform
the skill effectively and improve the speed and accuracy of the pass. These
principles include Force summation, 3rd class levers, impulse and
accuracy, and balance and stability.
Force
summation
The slap hit is a skill that requires momentum for the ball to be
released with speed. To create this momentum, the principle of force summation
is applied during the skill. Force summation is the combing of a number of
force producing movements used together in sequence to apply one final maximum
force upon the hockey ball (Blazevich,
2012). This is a result of momentum travelling through the largest and slowest
body parts such as the legs and hips and finishing with the smallest and
quickest body parts such as the wrists. The smaller body parts feed off of the
momentum from the bigger body parts producing a fast, dynamic movement. The
force of the muscle groups should be applied in the same direction and correct
sequence to achieve the greatest force (Wuest, 2009). In other words, in order
to create momentum moving forward, the muscle groups and body parts are used
sequentially to accelerate each body part. Perfect timing and stabilisers are
also important factors that affect force summation and the outcome of the
skill. As the first step is made and the front leg
stabilises, the principle force summation is applied. This begins in the larger
muscle groups of the legs, such as the quadriceps, hamstrings and
gastrocnemius. This force then begins to travel through the smaller body parts.
It travels through the hips and core as the body begins to rotate upon
contract. Once contact has been made, the upper body contracts with the biceps,
triceps and deltoids, then finishes off with the forearms and the rotation of
the wrists as the skill is completed and follow through occurs. If an
individual is not using each muscle to potential, for example the use of full
force of the lower body, then the movement relies on upper body strength rather
the summation of force. This would result in reduced force being applied to the
ball, therefore the pass being slower and even possibly inaccurate. If correct
sequence of the skill occurred, with using the full potential of each muscle
group, the summation of force would be maximised. During the preparatory phase,
force summation begins in the legs and hips. Through the contact and release
phase, force summation moves through the legs, hips and the trunk and
transferring through to the arms and upper body. During the follow through,
force summation is coming to and end as momentum has been generated through the
body. The force finishes with the smaller body parts like the wrists.
3rd
class levers
A third class lever is mostly used to describe levers within the
human body (Davidovits, 2008). This applies to a slap hit as the shoulder provides the fulcrum,
the effort is the stick and the resistance is the ball. This leads to a speed
advantage rather than a strength advantage, which is why the slap hit, is a
useful pass in a hockey game, as it assists in speeding up the game and keeping
the ball away from the opposition. The force arm is important in this skill, as
the longer the lever, the greater the velocity and momentum at impact. The
length of the external lever, the arm, is increased by the stick, therefore
producing a greater force. If the force arm is shortened, it reduces the length
of the lever, therefore reducing the speed. During a game, this could possibly
slow down the pass and make the pass inaccurate. For this to be improved, the
ball could be further away from the body, allowing the arm and stick to fully
lengthen to an almost straight arm. This increases the length of the lever by
extending the arms out further, producing a greater momentum and force being
applied to the ball (Davidovits, 2008). The 3rd class lever is mainly involved in the contact
phase. The longer the lever at contact, more momentum and power will be
generated at the release of the ball as the stick increases the length of the
force arm. This will make the speed, accuracy, and efficiency of the pass
higher then with a shortened lever.
Impulse and
accuracy
Impulse is the change of momentum that occurs when a
force is applied to an object. This relates to a slap hit because when the
stick makes contact with the ball, the balls momentum will change from zero to
a particular momentum before it leaves the stick. However, the balls momentum,
velocity and accuracy will depend on the force applied, which will be greater
if it can be applied for longer (Davidovits, 2008). This applies when contact is made
as a zone of flat line motion is created, also known as flattening the swing
arc. Within this skill, if the zone of flat line motion can be held longer, and
therefore increase contact time, a greater force will be applied, increasing
both the speed and accuracy of the pass. This applies when contact is made as a
zone of flat line motion is created, also known as flattening the swing arc. Within
this skill, if the zone of flat line motion can be held longer, and therefore
increase contact time, a greater force will be applied, increasing both the
speed and accuracy of the pass. If the ball is placed too far in front of the
body, then the contact time would be reduced and would not stay in contact
through to the follow through making the quality of the pass low. This
principle is applied during the contact phase where the longer the stick is in
contact with the ball, the more power is generated increasing the speed of the
pass.
Balance and
stability
In order for the slap hit to be performed, the leading
leg, in this case the left leg, must act as a stabiliser in a set position so
no further movement of the leg can occur until the skill is complete. This
provides the balance necessary to perform the skill since there is an unstable
equilibrium, as the ball continues to move forward once the force has been
applied (Blazevich, 2012). Centre of gravity and low wide base of support are
crucial principles within the slap hit to provide balance and stability when
moving forward, enabling an even distribution of weight required to remain
upright and steady while performing the skill (Davidovits, 2008). Throughout each stage of the skill (see image 4),
the centre of gravity remains within the wide base of support provided by the
muscle of the lower extremities, providing the balance necessary as the body
moves forward and rotates during the slap hit. The placement of the ball could
affect an individual’s balance and stability. If the ball is not within the
wide base support, the upper body would have to reach forward to make contact
with the ball. This would reduce the balance and affect the individual’s
ability to slap in a game situation, possible reducing the speed and accuracy.
During the preparation phase, the individual has a wide base of support with
their centre of gravity within the wide base of support. As the player moves
forward within the skill, the centre of gravity must remain within the wide
base of support to be able to remain balanced in order to perform the skill
effectively. If the individual were unstable, the skill would not be performed
with speed, accuracy and efficiency.
THE ANSWER:
In order to make an effective hockey slap hit, there are a number
of factors contributing to the quality of the skill. The main principles behind
the slap hit are balance and stability, 3rd class levers, impulse
and accuracy and force summation. Players that play at a high level have a good
wide base of support, in particular, to provide them with balance, which is
required for the skill to be performed. When all of these principles are
applied, the speed, accuracy and efficiency of the slap hit will be at the
level required to make a pass beat an opposition player during game play.
HOW ELSE CAN
WE USE THIS INFORMATION:
The biomechanical principles used within the hockey slap hit can
also be applied in other sports as well. We can use this information,
particularly in the baseball swing which has similar rotational movement as the
slap hit. The sweep shot in cricket also has the same movement as the slap hit.
Even though these are completely different sports to hockey, and each skill is
has its own elements, each skill requires a good wide base of support in order
to complete the skill effectively. Each skill also has a rotational movement
and relies upon force summation in order to create momentum throughout the
skill.
REFERENCES:
Hockey South Australia, 2014. Retrieved from http://www.hockeysa.com.au/Portals/19/Skills_of_hockey_tiers.pdf
Davidovits, P. (2008). Physics in Biology and Medicine (3rd ed.):
Academic Press.
Wuest, D. A., Butcher, C. A. (2009). Foundations
of Physical Education, Exercise science, and Sport. New York, NY:
McGraw-Hill
