Cramp in the Hamstring Muscles

Hamstring strain

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


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

Symptoms of a hamstring cramp

  • If you suffer a bout of cramps 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 cramps has passed, the muscle may be tender, sore or even have suffered a rupture (hamstring strain).

Causes of cramps in the hamstring muscles

What causes cramps? Although the exact cause of cramps 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, and electrolyte depletion result 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 cramps these muscles go into involuntary, painful spasms (contraction).

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Muscle strains from cramp

A bout of hamstring cramps 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 afterwards, although most muscle strains from cramps are relatively mild.

Treatment for a 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 cramps. Massage encourages blood flow and therefore relaxes the muscles.

If you have suffered a muscle tear as a result of a 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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