Cramp in the Hamstring Muscles

Hamstring strain

Cramp is a painful involuntary muscle contraction. Although leg cramp goes away naturally, it can damage the muscle and make it sore and tender.

Medically reviewed by Dr. Chaminda Goonetilleke, 21st Feb. 2021

Symptoms of a hamstring cramp

  • If you suffer a bout of cramp you will experience a powerful involuntary contraction of the hamstring muscles, at the back of the thigh.
  • It can be particularly painful and you will have great difficulty in straightening your knee.
  • Once your bout of hamstring cramp has passed, the muscle may be tender, sore or even have suffered a rupture (hamstring strain).

Causes of cramp in the hamstring muscles

What causes cramp? Although the exact cause of cramp has not yet been successfully determined there are thought to be a number of possible causes:

One theory states that muscle cramps are due to altered neuromuscular control, where muscles go into fatigue.  Also, there appears to be a genetic component making some people more prone to cramps.

Over time theories also include:

  • Dehydration (not taking on enough water, especially in hot conditions).
  • Low potassium or sodium (salt) levels.
  • Low carbohydrate levels.
  • Very tight hamstring muscles.

However, there isn’t enough evidence to suggest dehydration, electrolyte depletion results in cramps.

Hamstring muscles

The hamstring muscles

The hamstring muscles consist of the semitendinosus, semimembranosus and biceps femoris muscle at the back of the thigh. When an athlete suffers a bout of cramp these muscles go into involuntary, painful spasm (contraction).

Muscle strains from cramp

A bout of hamstring cramp may cause damage to the muscle. Fibres of the muscle are torn from the shear strength of the muscle contraction. This therefore, results in a hamstring strain. If this happens the muscle will be painful for some time afterward, although most muscle strains from cramp are relatively mild.

Treatment for hamstring cramp


If you are suffering from a bout of leg cramps, stretch the muscles involved. Hold the stretch for as long as is necessary. A partner may be very useful in assisting with the stretch.

hamstring cramp treatment stretch

Sports massage

Gentle massage to the muscles to the back of the leg, in particular, the hamstring muscles may help relieve cramp. Massage encourages blood flow and therefore relaxes the muscles.

If you have suffered a muscle tear as a result of hamstring cramp then wait until the initial acute phase has passed. This is usually 24 to 48 hours. Then deep tissue massage can be done to encourage healing.

If you do not have access to massage then a Foam roller is an excellent substitute and should form part of your warm up routine.

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