Figure
1: Six Biomechanical Components of the Instep Drive.
Introduction
Football (soccer) is the most
popular sport in the world and is enjoyed by millions of people worldwide. Some
fanatics have referred to it as more than sport, rather a way of life, where
some cultures see the beautiful game deeply imbedded into their history, some
even suggesting they consider football as important as religion
(Lees&Nolan, 1998). The most fundamental and frequently used technique for
kicking a soccer ball is known as the instep drive, or instep kick. Having an
optimal kicking technique is a significant consideration for any player wishing
to improve his shooting ability and long range passing. Therefore,
understanding the biomechanics of kicking a soccer ball is particularly
important for guiding and monitoring the training process. As Kellis et. al
(2007) outline, ‘improvement of the soccer instep drive technique is one of the
most important aims of training programs for young soccer players’.
To analyse a technique
thoroughly, critical examination from the biomechanical perspective provides
formidable framework to base investigations on, as it reviews each and every
movement pattern in light of producing the optimal result, thus maximsaing
positive performance. Lees et. al (1998) has defined biomechanics as, ‘the
science concerned with the internal and external forces acting on the human
body and the effect produced by these factors’. Exploration of the optimal
biomechanics of the Instep drive in soccer will be discussed, with reference to
supporting illustrations and a suggested critical analysis of how to produce an
optimal technique.
The science of biomechanics
contains seven fundamental principles for analysis: stability, maximum force,
maximum velocity, applied impulse, direction, angular motion, and lastly
angular momentum (Blazevich, 2010). Success of the soccer kick is determined and
influenced by several external variables also. For example, the distance of the
kick from the goal, the type of kick used, the air resistance, and of course
the three core movement phases best described using biomechanical analysis
(Kellis et. al 2007).
|
Table
1: Muscular action during kicking preparation (right-footed kick)
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||
|
Body part
|
Action
|
Muscles
|
|
Trunk
|
Stabilisation of rotation to
the right |
Abdominals, psoas major,
erector spinae and spinal postural muscles |
|
Right hip
|
Extension
|
Gluteus maximus and
hamstring group |
|
Left hip
|
External rotation and eccentric
extension
|
Gluteus med, gluteus min,
hamstring group and adductor magnus |
|
Right knee
|
Flexion
|
Hamstring group and popliteus
|
|
Left knee
|
Eccentric extension
|
Quadricep group
|
|
Right ankle
|
Plantarflexion
|
Plantarflexors
|
|
Left ankle
|
Eccentric plantarflexion
|
Plantarflexors
|
|
Left shoulder
|
Abduction
|
Middle and anterior deltoid
and supraspinatus |
Description: Instep Drive
The traditional three phase model
for the optimal Instep drive pass technique can be characterised by first
approaching the ball from a 45 angle with one or more strides, with placement
of supporting/ planted foot positioned beside the ball, with toes lining up to
the middle of the stationary ball. The next phase is the point of ball contact,
where the kicking leg is taken backwards and the leg flexes at the knee. From
here, the rotation of the pelvis is initiated around the planted/ supporting
leg by bringing the quadriceps muscle group of the kicking leg forwards, as the
knee continues to flex. After this initial action, the quadriceps muscles begin
to decelerate until it becomes basically motionless at moment of ball contact. Simultaneous to this deceleration, the knee
vigorously extends to almost maximum extension at the point of ball contact.
The kicking leg remains straight through ball contact and begins to flex again
during its long follow-through. Quite often, the finishing position of the
kicking foot after follow-through is above or of a similar level to the hip. (See
Figure 1 & 2 & 3 for visual representation of skills with frame-by-frame
isolation)
For a detailed analysis of the
instep drive skill in soccer, the skill its self can be broken into six smaller
sub components, thus allowing for deeper and more comprehensive examination of
the biomechanical principles in place at each stage in the skill pattern (Ghochani et. al, 2010). Proposed six sub-components of
the Instep drive as follows:
·
the approach
·
plant-foot forces
·
swing-limb loading
·
hip flexion and knee extension
·
foot contact
·
follow-through.
Video Link: Overview –Biomechanics of Instep Drive
Figure
2: In side view, a frame by frame Illustration of the insteps drive skill in
motion break-down.
Figure 3: Key Positions during the Instep drive skill.
a a)
Maximum
hip retraction.
b b) Forward
movement of the quadriceps muscle group with continued knee flexion.
c c)
Ball
contact
d d)
Post
Impact follow-through
e e)
Knee
flexion as follow through proceeds
Analysis Method: Biomechanical Implications (Quantitative Data
Collection)
The optimal method for collecting
necessary data revolves around video recording the skill. This image can be
slowed to detect intricate body motion, allowing for systematic analysis aimed
correcting and altering the current technique against that which is considered
to the optimal technique model. The use of technology in the way of motion
detection and frame-by-frame break down enables extended examination, thus
enabling the athlete to pin point potential parts of the technique to improve.
From captured video footage of the skill, data management for velocity,
acceleration, angle of ankle, and distance involved in the kicking activity can
be easily identified.
(1) Instep Drive: the Approach.
An important consideration
relating to the approach, that is all body movement pattern leading up to the
point of contact with the ball, is the angle with which the athlete approaches
the ball. Studies have shown that the maximum velocity of the shank was
achieved with an approach angle of 30 degrees and the maximum ball speed is
generated from an angle approach of 45 degrees (Ishii et. al, 2009). Lees et. al (1998) has provided a viable
explanation of this consideration. ‘An angled approach enables the leg to be
tilted in the frontal plane, so that the foot can be placed further under the
ball, thus making a better contact with it’. An interesting comparison exists
relating to the beginning of the instep drive, with either a running approach
or stationary. Mean maximum ball speeds of 23.5 m s- 1 when using a
stationary approach. By contrast, ball speeds of 30.8 m s- 1 when using a 5-8
stride running approach (Opavsky, 1988).
(2) Instep Drive: Plant-Foot
Forces
The
planted foot, or non-kicking foot is a significant factor in the instep drive’s
optimal technique. It should be be planted firmly, and pointing towards the
intended target. Studies have shown that there is a relationship between the position
of the planted foot and the direction of the instep drive (Opavsky, 1988 &
Lees, et. al, 2013). Thus, if you are aiming towards a set of goals, you
planted foot need to resemble that direction prior to contact with the ball.
Otherwise this will make for inaccuracy. As Sinclair et. al (2014) outline,
‘the optimal foot plant position for accurate direction is perpendicular to a
line drawn through the centre of the ball for a straight kick’. The planted foot determines trajectory
of the ball, it is therefore a major contributing factor to an optimal
technique.
(3) Instep Drive: Swing
Limb Loading
This
component of the instep drive involves the swinging of the kicking leg, as it
prepares for the downward motion of to project the ball forward. The opposite
arm of the kicking leg is raised in the air, serving as counter balance of
rotating trunk position. (Ishii et. al, 2009). The athletes eyes are fixed on the ball at this
point, promoting better performance of accuracy. Newton Third of equal and
opposite reaction is apparent in this component through the raising of the
opposite arm and back swing of the kicking leg. At this point, the plant foot
connects with the ground, adjacent to the ball, with an extended kicking leg.
The knee is also extending through flexion. Elastic energy is stored in during
this movement pattern, as this movement allows for maximal transfer of force
through the ball (Ishii et. al, 2009). Eccentric activity is present here, as
the hip flexors slow the movement of the kicking leg.
(4) Instep Drive: Hip
Flexion/ Knee Extension
This
phase involves the movement patter of the hips and knee, the quadriceps are
swung forward.
(5) Instep Drive: Foot Contact
‘Ball speed is a measure of
kicking success’ (Lees et. al, 2004). Significant variables for consideration
include: age, skill level and approach speed all effect the produced ball speed
of the instep drive. De Witt et. al (2012) proposes that there are 4 distinct
stages to the motion of the instep drive: Withdrawal of the quadriceps and
shank during back swing, rotation of the quadriceps and shank forwards, which
is a product of hip flexion, when quadriceps angular velocity reduces, there is
a corresponding increase in shank angular velocity up to the moment of impact
with the ball, and lastly the follow-through.
(6) Instep Drive: Follow-Through
The follow-through phase of the
instep drive technique has two fundamental purposes. (1) To keep the foot in
contact with the ball for as long as possible, and to guard against potential injury.
As is the case with all ballistic movements, a longer conact time with the ball
will maximize the transfer of momentum, thus increasing its overall speed (Shan
et. al 2005). The body protects itself from injury by gradually dissipating
kinetic and elastic forces generated by the swinging, kicking leg after ball
contact. A sudden slowing of the leg, that is, not allowing it to move through
the ball with sufficient follow-through can potentially increase the risk of
hamstring strains/ tears (Anderson et. al, 1994)
|
Table
2: Muscular action during follow-through (right-footed kick)
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|
Body Part
|
Action
|
Muscles
|
|
Right hip
|
Eccentric external rotation,
eccentric extension and eccentric abduction |
Hamstring group, posterior
fibres of gluteus med, quadratus femoris, piriformis and gluteus maximus |
|
Right knee
|
Eccentric flexion
|
Hamstring group
|
Other Factors Impacting Performance
Muscle strength is an important
factor in successful execution of the instep drive. Development of muscle
strength can be achieved through appropriate resistance training. It is worth
outlining that whilst this factor is significant in its contribution to the
optimal technique, it is not wholly determined by the improvement in muscle
strength. The technical, neuromuscular control of the movement must be
developed in conjunction with strength training.
The Answer
The literature reveals that
traditional models for biomechanical analysis suggest three core movement
components within the skill; the approach, point of contact with the ball, and
follow through (Sinclair et. al, 2014& Ismail et. al, 2010). However,
questions have surrounding this models authenticity because of its lack of
reference to significant factors such as upper body, pelvis and other movement
that influence the result of technique. As Shan et. al (2005) discuss,
‘effective soccer kicking uses full-body and multi-joint coordination’. The
six-component model suggested by Ghochani et. al (2010) represents an extended, more specific version of the
traditional three component breakdown of the instep drive movement pattern.
References
Anderson, D.
Sidaway, B. (1994). Coordination Changes Associated with Practice of a Soccer
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Blazevich,
A. (2010). Sports Biomechanics – The
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De Witt, J.
Hinrichs, R. (2012). Mechanical Factors Associated with Development of High
Ball Velocity During an Instep Soccer Kick. Sports
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Ghochani, A. Tabatabaee Ghomshe,
F. Rezvani Nejad, S. Rahimnejad, M.
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