Sunday, 2 December 2012

Muscle actions during Soccer Skills

Soccer practitioners require many attributes to become successful players. These include cardiovascular fitness, muscle strength, endurance, flexibility, agility, coordination, skill and tactical knowledge. Few players possess ‘natural ability’ in all areas, indeed the vast majority of players undergo training programmes, in some or all attributes, to improve their ability on the field.

Following are muscle actions which are part of soccer and which are important to be analyzed for physical fitness and strength for soccer.

1. Running

Running is an integral part of soccer. Indeed soccer players may cover approximately 10 km during a single game. The running action may be divided into two stages, swing and support. Support begins at the point when the foot makes contact with the ground (foot strike) and ends at the point when the foot leaves contact with the ground (toe-off). The swing phase begins at toe-off and ends at foot strike.
   At toe-off the swing leg is in a position of extension of the hip, extension of the knee and plantar-flexion of the ankle. The gluteals and hamstrings are still acting to extend the hip and the gastrocnemius to plantar-flex the ankle giving a good push off. The actions of psoas and iliacus flex the hip, the hamstrings flex the knee and the anterior tibials dorsi-flex the ankle. The hip continues to flex and the ankle to dorsi-flex to bring the leg forwards in front of the support leg; the adductors act to prevent the thigh from swinging outwards. The quadriceps then begin to extend the knee in preparation for foot strike.

When foot strike occurs the hip is in flexion, the knee is in slight flexion and the ankle is normally dorsi-flexed and slightly inverted. At this point the weight of the body must be controlled as it hits the ground. The gluteals contract to extend the hip, the quadriceps and hamstrings contract to stabilize the knee joint and the adductors to stabilize the hip. The anterior tibials work eccentrically and the gastrocnemius concentrically to control the foot as it strikes the ground. The momentum of the body carries it forwards over the ankle joint which acts as a rocker as the foot becomes flat to the ground and then toe-off occurs.

As the speed of running increases longer strides are taken. In this instance the swing phase involves greater knee flexion and hip extension (the heel almost touching the buttock) and greater hip flexion in the later part of the phase.
   When running with a ball much shorter strides are taken as the player must be ready to change direction and speed. At the toe-off phase the leg may not be as extended. Heel strike may not be as pronounced, instead the foot may land in a more neutral position or be plantar flexed.
   The muscles of the arms and trunk also play an important role during running. They act to maintain balance and to counterbalance the rotation of the body when the pelvis rotates.

2. Kicking a ball
There are many different types of kick in soccer, e.g. running kick, volley and push pass (Pronk, 1991). Skilled players can also impose spin on the ball and cause it to dip quickly in flight. In such cases the kicking action is quite complex. For the purposes of this text the kick is simplified into that of movement in one plane. This action may also be divided into four phases: phase one, priming the thigh and leg during back-swing; phase two, rotation of the thigh and leg laterally and flexion of the hip; phase three, deceleration of the thigh and acceleration of the leg; and finally stage four, the follow through.

During phase one the hip of the kicking leg is rapidly extended by the action of the gluteals and the pelvis is rotated backwards. The knee is flexed by the hamstrings and the anterior tibials dorsi-flex the ankle. These actions are limited by the hip flexors and the adductors which often become overstretched in many players. The harder the subsequent kick the further the stretch on these muscles. During phase two the psoas and iliacus contract and the hip flexes to move the thigh and leg forwards and the pelvis rotates forwards. Phase three involves the hamstrings acting to decelerate the thigh and the quadriceps rapidly extend the knee joint. The position of the ankle joint during ball strike is dependent upon the type of kick performed. In addition, the adductors will contract to pull the leg towards the body. This is especially relevant during a side kick or push pass. Phase four begins after the ball has lost contact with the foot, the leg and thigh will follow through due to the momentum of the thigh, leg and foot. This causes a stretch on the muscles opposing these actions, especially the hamstrings as they pass over two joints (De Proft et al., 1988).

The muscles of the non-kicking leg act in a similar fashion to their behavior during the stance phase of running. However, they act mainly to stabilize the body to provide a stable platform on which the kicking leg may act. This leg is usually abducted and rotated. Again the muscles of the arms and trunk work to maintain poise and balance and to provide a counterbalance to the kicking leg, thus providing more control and speed.

3. Jumping and heading
Jumping to control the ball in the air is of major importance in soccer. Jumping can occur from a standing position or from a run-up. Take off from a standing jump is usually from both feet and from one leg when using a run up. When performing a standing jump the player will sink down into a position of flexion. The trunk, hips and knees will flex and the ankle will dorsi-flex under the action of body weight and gravity but controlled by the agonist to these movements acting eccentrically (erector spinae, gluteals, hamstrings, quadriceps and plantar flexors). The elbows will flex and the shoulders will be extended. In this position the body is almost spring-like; the prime movers of the jumping action are on a stretch, storing potential energy ready to be released at the appropriate moment. When the jump itself begins the prime movers act to launch the body weight up in the air. This is achieved by rapid and powerful contractions of the erector spinae, gluteals, hamstrings, quadriceps and plantar flexors to produce extension of the trunk, hips, knees and plantar flexion of the ankles. The arms are also moved rapidly forwards and upwards by flexion of the shoulders and extension of the elbows. When the spine becomes extended during the jumping action a severe stretch may be placed on the abdominal muscles and the hip flexors and injury to these muscles may occur.

Landing from a jump is just as important as the jump itself, as the weight of the body must be controlled as it hits the ground. Basically it is a reverse of the jumping action. However, this time the muscles of jumping act eccentrically to control joint movement and decelerate the action, thereby increasing shock absorption and decreasing the risk of injury.

The primary aim of most jumps in soccer is to head the ball, but heading may also occur from a standing position. As a player jumps the neck becomes extended partly from the effects of gravity and partly due to the action of the erector spinae muscles. As a player attempts to make contact with the ball they will aim their head at it. This may involve a combination of movements. Flexion of the neck is the most powerful action but this may be combined with rotation or lateral flexion to direct the ball.

4. Throwing a football

Throw-ins are usually taken from a short run-up and a two-footed stance. With both feet level the erector spinae, gluteals and the hamstrings contract to extend the spine and the hips. The dorsi flexors act eccentrically to allow the ankles to move into a small degree of plantar flexion without losing balance. The ball is held in both hands and the two arms are held up above the head. The shoulders are moved into full flexion and the elbows also are now fully flexed. This creates full stretch on the antagonist groups and potential energy is stored. As the throw begins these now become prime movers which contract from a stretched position. The elbows become extended, the shoulders become more extended. The contraction of the abdominal and psoas and iliacus causes the spine and hips to flex. Dorsi flexion of the ankles is controlled by the eccentric action of gastrocnemius and soleus.
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