Conditions · Lower limb

Hamstring Strain !

A hamstring strain is a tear or overstretch of the muscles at the back of the thigh, common in sprinting; it causes sudden pain in the back of the thigh.

Updated 2026-10-23

Structures involved

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• Semitendinosus
• Semimembranosus
• Biceps femoris (long head)
• Biceps femoris (short head)

In histology

• Muscle injury, repair and satellite cells

Why it happens

• Skeletal muscle: sarcomere and contraction

What it is

Tear or overstretch of one or more of the hamstring muscles, common in sprinting and sudden acceleration.

Symptoms and signs

• Sudden pain in the back of the thigh
• Bruising or swelling
• Pain with knee flexion or hip extension

Diagnosis

Clinical

History and exam

Imaging

MRI or ultrasound for severe or proximal tears

Treatment

Rehabilitation

Graduated loading and physical therapy; most resolve without surgery.

Surgical

Repair considered for complete proximal avulsions in active patients.

Related conditions

• Piriformis syndrome

Educational information, not medical advice. For any symptom, see a health professional.

Sources: Hamstring Injury (StatPearls (NCBI Bookshelf), 2024).

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Representative model, for educational purposes only.