Monday, 24 September 2012

Resistance Training Exercises for Soccer

Resistance training is any exercise that causes the muscle to contract against an external resistance with the expectation of increases in strength, tone, mass and/or endurance. The external resistance can be dumbbells, rubber tubing, your own body weight, bricks, bottles of water, or any other object that causes the muscles to contract. 

Resistance training is a form of strength training in which each effort is performed against a specific opposing force generated by resistance(i.e resistance to being pushed, squeezed, stretched or bent). Exercises are isotonic if a body part is moving against the force. Exercises are isometric if a body part is holding still against the force. Resistance exercise is used to develop the strength size of skeletal muscles.

Suitable exercises can be divided according to the amount of skeletal muscle engaged. Exercises involving the arm and the shoulder joint may be described as light muscle group work whereas large muscle group work employs the muscles of the thigh and those of the trunk. Training these muscle groups in particular is relevant to soccer.

   It is important that the exercises are executed correctly, especially when loose weights are handled. The most common injuries in weight-training are to the wrists, back and knee. Mostly they occur when heavy weights are being lifted or when the technique is faulty (Reilly, 1981). Injuries to the back tend to occur when spinal flexion is permitted. Safety should override all other factors when heavy lifts are being attempted.

Many soccer clubs have strength training facilities on their premises. They are often designed for players to use during rehabilitation programs. Few clubs would have facilities on the scale available to American football players at a top University in the United States. Nevertheless the equipment available at a commercial gymnasium with a specialized facility for strength and conditioning work would accommodate a whole range.

Exercises for resistance training:


1. Squats

The squat thrust is one of the most favored exercises for games players. It does seem to be relevant to soccer. Wisløff et al. (2004) showed that maximal squat strength was correlated with sprint performance and vertical jumping in elite Norwegian players. The muscles involved are the plantar flexors of the ankle which act eccentrically to permit the closing of the ankle between the tibia and the foot, the extensors of the knee and hip, and the extensors of the spine and elevators of the scapula working isometrically. 

        In a full squat a loaded barbell is supported on the back of the neck. A piece of foam rubber or a towel is sometimes used to alleviate pressure on the cervical vertebrae. The body is lowered from a standing to a squat position, from which its weight plus the loaded barbell must be lifted by powerful contraction of the knee extensors. This exercise has been criticized because of the risk of incurring knee joint degeneration from strain on the patellar bursae. During deep knee bending without attendant weights, the patello-tendon force has been calculated to reach 7.6 times body weight (Reilly, 1981).

         In the full squat position with posterior aspects of thigh and calf in contact, the knee ligaments are overstretched and long-term ligamentous damage may be caused. In this position the lateral meniscus may also suffer from being caught between the femoral condyle and the tibial plateau (O’Donoghue, 1970). For these reasons performance of partial squats is advised, though full squats may be permitted at much less frequent intervals to provide maximum overload and maintain the joint’s range of movement.

          Maintaining stability during this exercise may present a problem for some individuals. Initially the player takes up a starting position with feet apart underneath the hips to provide best support for body weight. Stability is achieved by keeping the line of gravity within the base of support. This aim is effected by pushing the hips back slowly as the body weight is lowered. By retaining heel contact with the ground the base of support is kept relatively large and stability is facilitated.

      Balance may be assisted by elevating the heels by means of an inclined board or by performing the exercise with a board placed underneath the heels. A more satisfactory procedure is to use a steel rack which arrests movement of the bar in the fore and aft direction and which incorporates obvious additional safety factors. These racks are installed in all well-equipped gymnasia.

            More weight can be lowered than lifted, as the muscles work eccentrically when lowering a load compared to contracting concentrically when lifting it. Therefore, a useful modification of the half-squat is to overload the individual beyond maximal lifting capacity and to allow him/her to lower the weight slowly under eccentric muscular control. A weight about 120% of lifting capacity can easily be handled for six repetitions. If the stretching force is 130 to 140% of one concentric repetition maximum (1 RM), it is not possible to slow the lowering sufficiently in a free movement resisting gravity to permit the involved muscles to develop maximal tension. For safety purposes the load should be supported by pins at the end of the eccentric movement.

2. Power Clean:

This exercise involves approximately the same energy demands as a full squat (Reilly, 1983). The weight is lifted from the floor to above head height in one complete movement. Special attention to technique is needed in the initial-lifting movement. The knee-lift, with the back straight to prevent the turning of the spine into a cantilever with consequent spinal strain, is preferable to the back-lift with knees straight. Correct placement of the feet is essential prior to attempting the lift. The player should become accustomed to performing the action with the head erect and looking directly ahead in order to avoid the natural temptation to look down at the weight as he/she attempts to overcome its inertia. As the forces on the spine are a function of the distance the weight is away from it, it is recommended to keep the weight close to the body as it is being lifted.

         It is important not to suspend breathing when heavy weights are held overhead. When the breath is held and the epiglottis closed, intra-thoracic pressure is increased to a point that precipitates the Valsalva manouvre. This action results in a reduced venous return to the heart and consequent rapid drop in blood pressure with possible loss of consciousness. International weightlifters have been known to faint and lose consciousness during competition as a result of failure to time their breathing correctly.

3. High Pulls:

This exercise involves the same gross muscular action and equivalent energy expenditure as power cleans (Reilly, 1983). The barbell is taken from the floor to a height roughly in line with the clavicles. The player may increase the work done by coming up on to his or her toes to complete the lift, good co-ordination being demanded for this action. The elbows are raised above the bar at its high-point, which does not go overhead. Again it is important to keep the back straight during the lift as jerking into back extension, particularly during the early phase of the action, can lead to injury. The major muscles engaged in this exercise are the ankle plantar flexors, the extensors of the spine working isometrically, the shoulder abductors, elbow flexors and the elevators of the scapula.

4. Bench Step-ups:

Body-weight plus a weighted barbell provide the resistance as the individual steps repeatedly on to a bench with load supported on the shoulders. Ideally the bench should be matched to the stature of the individual, otherwise there is a risk of a quadriceps muscle tear where the smaller players operate with a high bench. When the weight used is too heavy, the rhythm of stepping may be disrupted with consequent danger of losing balance and incurring injury.

5. Leg Press:

This exercise entails knee extension and can be done from different postures. It is usual to start from a sitting position with the knees and hips flexed. Peak torque is generated at about 120 of knee extension and if the hip is flexed too much the angle of the knee will not allow enough force to be developed to move heavy weights. An alternative starting posture is a recumbent
supine position from which the weights are pushed upwards and vertically. It is recommended that the lowering of the weights to the starting position is performed under careful control.

6. Leg Curls:

In order to maintain the correct balance between flexion and extension, the hamstrings should be trained as well as the quadriceps. An appropriate exercise is knee flexion with the subject in a prone position. This activity is best performed using a fixed training station. The muscles are engaged eccentrically as the load is returned to its starting position.

7. Trunk Exercises:

Sit-ups (trunk curls or crunches)

The resistance is normally provided by approximately half the body mass which the abdominal muscles must move against gravity. The load on the abdominal  in a sit-up action from supine lying can be increased by holding a loaded barbell on the chest. This exercise is preferable on comfort criteria alone to holding a disc behind the neck. A partner may hold the ankles of the athlete to facilitate the action. Another variation is to sit-up with a twist, arms behind the ears, to touch each knee alternately with contra-lateral elbows.

         Exercise for the abdominal muscles is commonly known as performing ‘the crunch’ and there are several commercially available devices with claims of enhancing the training stimulus. Robinson. (2005) used electromyography of lower rectus abdominis, upper rectus abdominis and obliques externus abdominis muscles to investigate the effectiveness of five different abdominal exercises; these included a sit-up (crunch) with a 5-kg weight held behind the head and a sit-up with a commercial roller-crunch device. The highest stimulus to all three muscles was provided by a crunch whilst sitting on a ‘gym ball’, and a crunch with legs raised. The greater muscle activity in these exercises was attributed to the unstable surface and the need to support the legs off the ground. The commercial aid was no different from a standard sit-up in the muscle activity it induced.

8. Back Extension:
A basic exercise for the spinal muscles is to assume a prone position on the ground with the arms extended over the head and touching the floor. The head, arms and legs are then raised off the floor and this position is held for about 6 s. After a 5-s rest the exercise is performed up to 12 times.

An alternative is to take up a standing position, crouched at the hips with a barbell on the shoulders. The back is kept straight whilst the weight is lifted upwards, then lowered in a controlled manner to the starting point. This exercise must be done carefully and unduly heavy weights avoided.
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