How is Muscle Structured?

In order to understand how muscles are injured it is helpful to know how the muscle is made up. The muscle is surrounded by an outer sheath or covering. Inside this outer sheath are bundles of muscle fibres which are known as fasicles and are themselves surrounded by another inner sheath. If you looked at the bundles very closely you would just be able to see the individual muscle fibres. (The muscle fibres are made up of even smaller parts but a microscope is required to see them).

A muscle contracts when two of these microscopic parts link together and slide together (causing the muscle to shorten) or slide apart (causing the muscle to lengthen). If the muscle shortens, the result is movement of a joint in one direction; if it lengthens, it causes movement of a joint in the other direction. The co-ordination of this muscle activity by the brain allows us to perform complex movements such as kicking a football or running.

What is a Muscle Strain?

A muscle strain is damage caused by over-stretching of muscle tissue. In football, this is thought to occur most frequently when movements such as sprinting, stretching for the ball or kicking the ball are carried out in an unco-ordinated manner. The muscle tissue becomes overloaded and reaches a breaking point where a tear or partial tear occurs. The player will experience pain that will persist if he or she attempts to stretch or contract the muscle. Depending on their severity, muscle strains are categorised into Grades 1, 2 or 3:

• GRADE 1 STRAIN
  There is damage to individual muscle fibres (less than 5% of fibres). This is a mild strain which requires 2 to 3 weeks rest.
• GRADE 2 STRAIN
  There is more extensive damage, with more muscle fibres involved, but the muscle is not completely ruptured. The rest period required is usually between 3 and 6 weeks.
• GRADE 3 STRAIN
  This is a complete rupture of a muscle. In a sports person this will usually require surgery to repair the muscle. The rehabilitation time is around 3 months.

All muscle strains should be rested and allowed to heal. If the patient continues to play, the condition will worsen. If ignored, a grade one strain has the potential to become a grade two strain or even a complete rupture.

How does a Damaged Muscle Heal?

The healing process of a muscle strain begins with an inflammatory response which can last for three to five days. This is a crucial time during which rest and protection of the injured part is vital in order to prevent any further damage. During the inflammatory reaction the body produces chemicals and cells which remove dead muscle fibres and start the repair process. The repair process consists of three stages:

•  REGENERATION OF MUSCLE FIBRES
New muscle fibres grow from special cells within the muscle.

•  FORMATION OF SCAR TISSUE
There is bleeding in the gap between the torn muscle ends, and from this blood a matrix, or scaffold, is formed to anchor the two ends together. This matrix eventually forms a scar within the muscle that makes the muscle more resistant to further stretch damage.

•  MATURATION OF THE SCAR TISSUE
The collagen fibres which make up the scar tissue become aligned along lines of external stress and are able to withstand more force.

How are Muscle Injuries Treated?

The immediate treatment consists of the 'PRICE' protocol: Protection of the injured part from further damage, Rest, Ice, Compression and Elevation. The aim of this protocol is to reduce bleeding within the muscle tissue. Ice therapy in the form of ice pack applications should be continued for the first three days after the injury (never apply ice directly to the skin). The rehabilitation after this period involves gradually stretching the muscle to elongate the scar tissue and progressively increasing the muscle strength. Once this has been achieved, the player can begin sport-specific exercises, such as running, jumping and kicking. To reduce the risk of re-injury, this should be done under the supervision of a chartered physiotherapist .

How can the Risk of Muscle Injury be Reduced?

The following measures may have the effect of reducing the chances of sustaining a muscle strain:

• Warm up prior to matches and training is thought to decrease muscle stretch injuries because the muscle is more extensible when the tissue temperature has been increased by one or two degrees. A good warm up should last about twenty minutes - starting gently and finishing at full pace activity. Practising match activities such as sprinting and passing helps tune co-ordination and prepare mentally for football. Recovery after training sessions and matches can be enhanced by performing a cool down, which is thought to help muscles get rid of waste products. This is also the ideal time to do stretching execises.
  Read our guide to warming up >
  Read our guide to cooling down >
  
• Maintaining good muscle strength and flexibility may help prevent muscle strains. Muscle strength allows a player to carry out match activities in a controlled manner and decreases the uncoordinated movements which can lead to injury. Tight muscles are associated with strains and stretching is therefore practised to maintain muscle strength and prevent injury.
  Read our guide to stretching >
  
• Diet can have an affect on muscle injuries. If a player's diet is high in carbohydrate in the 48 hours before a match, there will be an adequate supply of the energy which is necessary for muscle contractions. However, if the muscles become short of fuel, fatigue can set in during training or matches. This fatigue can predispose a player to injury. Carbohydrate and fluids can be replenished during training and matches by taking regular sips of a sports drink.

Common Muscle Injuries

Adductor muscles - these are commonly injured during football because they are put under a great deal of stress during turning activities. They are also very active during side foot passing.

Hip flexor muscles - these are the kicking muscles at the front of the hip which are very active during shooting and striking a ball.

Quadriceps muscles - these powerful muscles of the thigh are responsible for straightening the knee and are active during running, kicking and jumping.

Hamstring muscles - these muscles are located at the back of the thigh and are most active during running, particularly sprinting, which is when they are most often injured.