Hamstring strain

The hamstrings are three muscles along the back of the thigh that run from the pelvis to just below the knee. They extend the hip and bend the knee and work especially hard during sprinting. A hamstring strain is a stretch or tear of these muscles or their tendons, ranging from a mild pull to a complete tear.

• Sudden, sharp pain in the back of the thigh during activity, sometimes with a pop
• Pain when walking, straightening the knee, or bending forward
• Tenderness in the back of the thigh
• Swelling and bruising that may appear over a few days and spread toward the knee
• Weakness in the leg
• With a severe tear near the buttock, a large bruise and difficulty walking

• Sprinting, sudden acceleration, and quick starts and stops, common in track, soccer, football, and basketball
• Overstretching, as in high kicks, dance, or waterskiing
• A previous hamstring strain
• Muscle fatigue, skipping a warm-up, and tight or weak hamstrings
• An imbalance between the strength of the front and back thigh muscles

A clinician examines the thigh for tenderness, swelling, a gap in the muscle, and weakness. Strains are commonly graded:

• Grade 1: a mild strain, or pulled muscle
• Grade 2: a partial tear
• Grade 3: a complete tear of the muscle, or of the tendon from the bone

An MRI or ultrasound is used for severe injuries, especially when the tendons may have pulled away from the sitting bone at the base of the pelvis.

Most hamstring strains heal without surgery. Early care includes rest, ice, compression, and elevation, crutches if walking is painful, and anti-inflammatory medication when appropriate. Physical therapy then guides gentle stretching, progressive strengthening, core and hip exercises, and a stepwise return to running.

Surgery may be recommended when the tendons have pulled completely away from the bone, most often at the pelvis. This injury is evaluated promptly, because repair is more straightforward soon after the injury.

Mild strains may settle within days to a few weeks, while severe tears can take months. Return to sport is based on full strength and flexibility and on pain-free sprinting, not on time alone; returning too soon raises the chance of another strain.

Regular hamstring strengthening, including eccentric exercises such as Nordic hamstring curls, a thorough warm-up, gradual increases in training, and adequate rest can lower the risk. Continuing the strengthening program after returning to sport helps prevent another injury.