The hamstrings muscle group consist of 4 muscles that are located behind your leg. The action of these muscles combined is to perform hip extension and knee flexion. The hamstring muscle is the most commonly strained muscle in the lower part of elite athletes. A hamstring strain is when these muscles are strained from excessive load during contraction or extreme stretching. The strain is classified into 3 grades.

• Grade 1 represents strain without significant fibre tearing
• Grade 2 indicates partial muscle tearing
• Grade 3 is complete muscle or tendon rupture

The majority of hamstring sprains occur suddenly during activity, with a tearing feeling accompanied by significant pain. The symptoms will often depend on the grade of hamstring strain you get.

• Grade 1 hamstring strains will cause pain that is sudden with tenderness at the back of the thigh. It can be painful to move the leg but the strength of the muscle is usually unaffected.
• Grade 2 hamstrings trains where there is partial muscle tearing is more painful and tender. There could also be swelling and visible bruising behind the thigh with the possibility of some loss of strength in the leg.
• Grade 3 hamstring strain is where there are severe tears in the hamstring muscle. This is usually extremely painful and tender. There will be severe swelling and bruising which may have been followed by a “popping” sensation at the time of injury. Depending on the severity of the tears you may be unable to move the affected leg.

Hamstring strains usually occur as a result of excessive overloading and stretching beyond their limit. This can occur during sudden, explosive movements such as sprinting, lunging or jumping. They do however also occur slowly over time with movements that stretch beyond your limits.

Several other factors increase the risk of developing a hamstring strain such as:

• Insufficient warmup
• History of prior injury
• Hamstring that is inflexible or weak
• The muscular imbalance between the hamstrings and the quads. The injury occurs if the quads overpower the capacity of the hamstrings to decelerate forwards progression of the leg while sprinting

The diagnosis of a hamstring strain is made based upon an accurate history of symptoms and a combination of clinical tests that the practitioner will utilise. The practitioner may palpate the muscle and perform strength tests to determine the severity of the strain along with other tests that they find appropriate in the session.

Imaging studies are reserved for extreme cases such as a grade 3 strain to help determine whether a surgical intervention will be needed.

The average recovery period of a hamstring injury ranges from one to three weeks and is based on the severity and location of the injury. The closer the site of injury is to the buttocks the longer the recovery periods. Injuries that have occurred as a result of slow speed stretching generally take longer to heal. Recurrent injuries usually take twice as long to heal as the initial injury.

If the rehabilitation is not done adequately and return to sports is premature, there is a greater risk of re-injury and reduced performance.

Fortunately, grade 1 to grade 2 strain injuries usually heal on their own. There are things you can do to reduce the recovery time and to ensure that re-injury is minimal by following a rehabilitation programme.

The rehabilitation of the hamstrings is divided into 3 phases:

Phase 1 – A campaign of rest, ice, compression and elevation should be initiated immediately following the injury.

• Rest should involve immobilising the leg, including the use of crutches if the strain is severe. The leg should be straight at most times as a bent knee position puts excessive pressure on the hamstring muscles.
• Ice is used to reduce pain and inflammation and should be used for 30 minutes at a time, about 2-3 times a day until the pain is reduced.
• A compression bandage may help reduce intramuscular swelling.

Phase 2 – This phase will begin once you are able to walk without pain and are able to tolerate a moderate degree of resisted knee flexion. The goal of phase 2 is to improve flexibility, strength and biomechanical function of the hamstring and any related lumbar or pelvic issue that may be underlying.

Phase 3 – Begins when you are able to perform pain-free resisted knee flexion and can run at 50% speed without pain. This phase will focus on getting you to returning to activity with the help of sport-specific drills and stabilisation.

Lieberman GM, Harwin SF. Pelvis, hip, and thigh. Sports Medicine: Principles of Primary Care. St Louis, Mosby. 1997:306-35.

Kerkhoffs GM, van Es N, Wieldraaijer T, Sierevelt IN, Ekstrand J, van Dijk CN. Diagnosis and prognosis of acute hamstring injuries in athletes. Knee Surgery, Sports Traumatology, Arthroscopy. 2013 Feb 1;21(2):500-9.

Kujala UM, Orava S, Järvinen M. Hamstring injuries. Sports medicine. 1997 Jun 1;23(6):397-404.

Koulouris G, Connell DA, Brukner P, Schneider-Kolsky M. Magnetic resonance imaging parameters for assessing risk of recurrent hamstring injuries in elite athletes. The American journal of sports medicine. 2007 Sep;35(9):1500-6.