Task 4: Common causes & prevention


P. Brukner states that hamstring strains commonly occur while sprinting, hurdling or jumping. Because the hamstring muscle constantly undergoes eccentric contraction when performing movement (muscle lengthening), it is subject to being stretched too far when athletes performing a jump, quick burst of movement or stretch out. Often hamstring injuries occur when the muscle is extended whilst is weighted or loaded.

One of the more common causes of hamstring injuries is an inadequate warm-up. W. Garret states that flexibility is temperature dependent; therefore cold muscles do not stretch as effectively as warm muscle. One way to prevent this is to warm the muscles prior to exercise via an efficient warm-up that includes dynamic stretching, jogging, etc.

An imbalance of strength between different joints and muscles are also a common cause of hamstring strains.
Individuals with a decreased strength ratio between the hamstrings and quadriceps are less likely to resist the force during a powerful concentric contraction by the quadriceps (Croisier, 2002).

Also previous knee and groin injuries can lead to a reliance upon the hamstrings to work harder for a given amount of work, risking a strain injury (Verrall, 2001).

Muscle fatigue is one of the more prevalent factors in hamstring injuries.

There also is a tendency towards increased incidence with increasing age. GM Verrall states that the flexibility of older athletes may decline due to deterioration in the contractile elements that contribute to muscle flexibility. It is a common injury amongst older athletes, particularly those who play codes of football such as AFL & soccer that require a swing phase of the muscles when performing kicks.

Hamstring strains are subject to being reinjured if the athlete has not fully rehabilitated. The formation of scar tissue in the healing process may decrease the ability of the muscle to stretch under a given load, creating further risk of injury for the athlete (Garret, 1996).
M. Verrall states that this may increase the risk of re-injury by as much as five times.


The following video is an example of one of the main causes of hamstring injuries - jumping, hurdling and high intensity running.


<http://www.youtube.com/watch?v=6-5Ay-Z4Wsw>