Hamstring muscle strains are a common injury in sports, especially those that involve sprinting, bending down and turning and as athletes get older.
The hamstring group comprises three muscles - biceps femoris, semi-tendonosus and semimembranosus. The action of these muscles is to bend the knee and extend the hip, especially on faster running.
Hamstring injuries are sometimes known as a 'pulled Hamstring'. Usually, the Hamstring muscle is forcibly stretched beyond its limits and the muscle tissue becomes torn. A tear in the Hamstring muscle is referred to as a Hamstring strain and depending on its severity it is classified as a first, second or third degree strain. This grading largely influences the time frame of when sport can be resumed:
- First degree strain is damage to a few muscle fibres
- Second degree strain is damage to a more extensive number of muscle fibres
- Third degree strain is a complete rupture of the muscle itself
Through asking specific questions, giving the history of the problem and through clinical testing, the Musculoskeletal Physiotherapist is able to grade the injury, give guidance around rehabilitation and also give a prognosis on the likely timeframe to return to running and sport.
For acute, mild or moderate hamstring injuries, an MRI or Ultrasound is not required for estimating the duration of rehabilitation, however if a third degree strain is suspected, these investigations may be recommended.
Many athletes return to sport too early and without adequate rehabilitation. Recurrence of injury is very high and is closely associated with previous injury, using anti-inflammatories after the injury, loss of flexibility of the hamstring and the severity of the original injury.
All athletes ask the question: “When can I return to play”.
This may be anywhere from 1-12 weeks depending on the grade of the strain and other variables such as the type of sport, age and pre-existing injury.
Specific factors associated with a return to play of more than 3 weeks include:
- The number of days taken to be able to walk pain free
- Past history of previous hamstring injury
- A difference of 10% or more between sides in the ability to straighten the knee when the hip is flexed to 90 degrees in lying (active knee extension test)
- Involvement of the lateral hamstring muscle group (Bicep Femoris)
M. Sherry and T. Best (2004) A Comparison of 2 Rehabilitation Programs in the Treatment of Acute Hamstring Strains JOSPT vol 34 (3) pp 116-125
M.E. Schneider-Kolsky, J. Hoving, P.Warren and D. Connell (2006) A comparison between clinical assessment and magnetic resonance imaging of acute hamstring injuries. Am J of Sports Med vol 34(6) pp 1008-1015
P.Warren, B. Gabbe, M. Schneider-Kolsky and K. Bennell (2010) Clinical Predictors of Time to Return to Competition and Recurrence following Hamstring Strain in Elite Australian Footballers BJSM vol 44(6) pp 415-419