The hamstring muscles (3 muscles: semitendinosus, semimembranosus, and biceps femoris) are large muscles that attach to the pelvis, run down the back of the thigh, cross the knee and attached at the upper end of the lower leg bones.

These muscles allow us to extend the leg and bend the knee. The hamstrings are balanced by the quadriceps muscles on the front of the thighs

Muscle overload is the main cause of a hamstring tear.

Risk factors include muscle tightness, muscle imbalance (the quadriceps are stronger than the hamstrings), poor conditioning, muscle fatigue and sports that involve lunging, sprinting, running, and jumping such as tennis, track, soccer, football and basketball

The most common site for a muscle tear is the middle of the hamstring muscle.

Symptoms depend on the grade of the strain. A mild strain may feel like an ache or pulling pain that worsens with activity. Symptoms of a grade 2 or 3 strain can include:

• A sharp pain in the middle back of the thigh

• Difficulty putting weight on the injured leg causing limping

• Swelling

• Bruising and discoloration

• Hamstring weakness

• Muscle spasms

• Some people hear a pop when the muscle is injured

• Sometimes, sciatic nerve pain

Conservative treatment involves rest, ice, compression, and elevation, anti-inflammatory medications and activity modifications. Physical therapy cna be added for moderate to severe lesions

Surgery may be needed to repair a complete rupture or for bone avulsion

Stretching and range of motion exercises are important to rehabilitation, followed by strength training. It can take a few months to return to play. Reinjury is common, often caused by a premature return to sport.