|
(b) |
The approach is the first movement phase of a soccer kick and is an
important aspect for developing momentum and therefore velocity (Wang and
Griffin, 1997). The approach is traditionally 2-4 steps however; a shorter
approach can mean that the ball is struck sooner allowing faster attack and
less time for defensive structures to assemble (Wang and Griffin, 1997).
Potential energy is associated with a position and can be used to increase
speed as adopting a good starting position will result in less steps and a
faster attack (Blazevich, 2010). This starting position can be seen in figure 1
(a) and has the potential to gain kinetic energy (Blazevich,
2010).
In the initial stages of the approach as seen again in
figure 1 (a) the chest is leading forward, where the centre of gravity is
outside the centre of mass. However this changes throughout the approach as the
player moves closer to the ball at the final curve of the approach, the centre
of gravity shifts towards the inside of the curvilinear path as displayed in
figure 2. This helps create forward momentum and power due to the
summation of forces and an overall increase in acceleration speed, resulting in
a greater overall velocity of the action. (Blazevich, 2010) Hip flexion in this
direction enables for a greater range of motion later in action, at ball/foot
contact (Blazevich, 2010). This allows for greater hip flexion to occur, thus
facilitating increased torque about the hips, translating through the kinetic
chain into a faster and more powerful kick (Blazevich, 2010).
Many
players favour an angled approach as scientific studies show a 45-degree angle
is optimal for facilitating maximum ball speed (Eleftherios and Athanasios,
2007). This angled approach is also known as a curvilinear path in
biomechanical terms (Blazevich, 2010). This angled approach enables greater
pelvic rotation and limb-swing velocity creating a greater range of motion and
overall increases speed (Eleftherios and Athanasios, 2007). This curved
approach assists in facilitating the leading foot to be planted perpendicular
to the ball, increasing the time and range of motion for the kicking leg to be
rotated about the body (Blazevich, 2010). Therefore, greater torque forces are
able to generated at the hip and knee flexion points (Blazevich,
2010).
|
(c) |
The approach is most successful when executed on the balls of the
feet as this allows players to increase their propulsive impulse and reduce
breaking impulses in the lead up to making contact with the ball (Blazevich,
2010). All steps should be positioned reasonably close to the body with high
hip extension reducing contact time with the ground to create fast explosive
steps (Blazevich, 2010). If strides are extended in their approach it will create an increase breaking impulses and reduce
acceleration and speed, (Blazevich, 2010). However the final step should
be extended in front of the body and can be seen in figure 1 (c) in order to
increase range of motion in the swing pathway of the kicking leg (Blazevich,
2010).
The arms play a significant role in producing speed but also
maintaining balance as the swinging of the arms increases leg speed and creates
body rotation (Blazevich, 2010). This technique involves backwards rotation of
the arms along a sagittal plane in opposition to the legs to create speed and
power (Blazevich, 2010). This is because the torque created by the ground
reaction force changes, therefore the arms must also adapt and change
(Blazevich, 2010). When the foot is out in font of the body the arm is bent
creating an acute elbow angle and can be seen in figure 4, however when the
foot strikes the ground the arm will lengthen, almost extending straight out
which increases it’s angular momentum (Blazevich, 2010). When the arm is
extended it increases the moment of inertia, which increases angular velocity
and translates through the kinetic chain overall creating a faster approach
(Blazevich, 2010). As the running action continues the foot falls behind the
body, this is where the arm begins to shorten again and reduces its angular
momentum. This technique allows angular momentum of the upper of lower body to
work in an equal and opposite manner creating forward momentum and speed
(Blazevich, 2010). Overall the quicker the arms the more angular momentum it
possesses and greater speed can be produced.
|
Figure 4 |