A hamstring injury is a strain or tear to the tendons or large muscles at the back of the thigh.

This type of injury is common in athletes and can occur in different severities. The three grades of hamstring injury are:

• grade 1 – a mild muscle pull or strain
• grade 2 – a partial muscle tear
• grade 3 – a complete muscle tear

The length of time it takes to recover from a hamstring strain or tear will depend on how severe the injury is.

A minor muscle pull or strain (grade 1) may take a few days to heal, whereas it could take weeks or months to recover from a complete muscle tear (grade 3).

The hamstrings

The hamstrings are tendons (strong bands or cords of tissue) at the back of the thighs that attach the large muscle of the thigh to the bone.

The term hamstring also refers to the group of three muscles that run along the back of your thigh, from your hip to just below your knee.

The hamstring muscles aren't used much while standing or walking, but they're very active during activities that involve bending the knee, such as running, jumping and climbing.

What causes hamstring injuries?

The hamstring muscles allow you to extend your leg behind your body and to bend your knee. An injury can occur if any of the tendons or muscles are stretched beyond their limit.

Hamstring injuries often occur during sudden, explosive movements, such as sprinting, lunging or jumping. If the tendons or muscles tear, you may feel or hear a pop, followed immediately by severe pain in the affected leg.

The muscle will often spasm (seize up) and feel tight and tender. In severe cases, there may also be swelling, tenderness and bruising. Walking may be painful.

In athletes and sportsmen, such as footballers, recurring injury is common.

Rest and recovery

Recovering from a hamstring injury may take days, weeks or months, depending on how severe the strain or tear is.

A completely ruptured (torn) hamstring (grade 3 injury) may take several months to heal and you'll be unable to resume training or play sport during this time.

During the first few days after the injury, you should rest the affected leg. Follow the steps below.

• Rest – keep your leg as still as you possibly can and avoid physical activity
• Ice – apply ice to your hamstring for about 20 minutes, two to three times a day (don't apply it directly to your skin; you can use a bag of frozen peas wrapped in a tea towel)
• Compression – a compression bandage can help reduce pain and swelling
• Elevation – keep your leg slightly raised while sitting to help reduce swelling

Resting means not running or jumping while you're injured. However, if the pain allows, you can do gentle exercise, such as swimming, walking and cycling.

Over-the-counter painkillers, such as ibuprofen or paracetamol, may also help relieve the pain.

Gentle exercises and stretches

If you have an injured hamstring, it's important that you don't stay inactive for too long because it can cause your hamstring muscles to shrink and scar tissue to form around the tear.

Once the pain has subsided, and after resting for several days, you should start to do regular gentle hamstring stretches.

This should be followed by a programme of gentle exercise, such as walking and cycling, and hamstring strengthening exercises.

Your GP will be able to give you further advice and, if necessary, refer you to a physiotherapist to start a suitable graded exercise programme.

To avoid injuring yourself again, you should only return to a full level of activity when your hamstring muscles are strong enough. Reintroduce running to your exercise programme gradually. Your physiotherapist will be able to advise you about this.

Always do a proper warm up before exercising and cool down and stretch afterwards. Stop immediately if the pain returns.

Find out how to stretch after a run.