A hamstring injury involves straining or pulling one of the hamstring muscles — the group of three muscles that run along the back of the thigh.

Hamstring injuries often occur in people who play sports that involves sprinting with sudden stops and starts. Examples include soccer, basketball, football and tennis. Hamstring injuries can occur in runners and in dancers as well.

Self-care measures such as rest, ice and pain medicine are often all that's needed to relieve the pain and swelling of a hamstring injury. Rarely, surgery is done to repair a hamstring muscle or tendon.

A hamstring injury typically causes a sudden, sharp pain in the back of the thigh. There might also be a "popping" or tearing sensation.

Swelling and tenderness usually develop within a few hours. There might be bruising or a change in skin color along the back of the leg. Some people have muscle weakness or are not able to put weight on the injured leg.

When to see a doctor

Mild hamstring strains can be treated at home. But see a health care provider if you can't bear weight on the injured leg or if you can't walk more than four steps without a lot of pain.

The hamstring muscles are a group of three muscles that run along the back of the thigh from the hip to just below the knee. These muscles make it possible to extend the leg back and to bend the knee. Stretching or overloading any one of these muscles beyond its limit can cause injury.

Hamstring injury risk factors include:

• Sports. Sports that require sprinting or running might make a hamstring injury more likely. So might other activities that can require extreme stretching, such as dancing.
• Earlier hamstring injury. People who have had one hamstring injury are more likely to have another one. This is especially true for people who try to go back to the same activities before the muscles have time to heal.
• Tired muscles, weak muscles and muscles that don't stretch well. Tired or weak muscles are more likely to be injured. Muscles with poor flexibility might not be able to bear the force of the action that certain activities require.
• Muscle imbalance. Although not all experts agree, some suggest that a muscle imbalance may lead to a hamstring injury. If the quadricep muscles along the front of the thigh are stronger and more developed than the hamstring muscles, injury to the hamstring muscles might be more likely.
• Age. Risk of injury increases with age.

Returning to tiring activities before hamstring muscles are completely healed might cause the injury to happen again.

Being in good physical condition and doing regular stretching and strengthening exercises can help lessen the risk of a hamstring injury. Try to be in shape to play your sport. Don't play your sport to get in shape.

If you have a job that's physically demanding, staying in shape can help prevent injuries. Ask your health care provider about good exercises to do regularly.

During the physical exam, a health care provider checks for swelling and tenderness along the back of the thigh. Where the pain is and how bad it is can give good information about the damage.

Moving the injured leg into different positions helps a provider pinpoint which muscle is hurt and whether there is damage to ligaments or tendons.

Imaging tests

In severe hamstring injuries, the muscle can tear or even separate from the pelvis or shinbone. When this happens, a small piece of bone can be pulled away from the main bone, known as an avulsion fracture. X-rays can check for avulsion fractures, while ultrasound and MRIs can show tears in the muscles and tendons.

To care for a minor hamstring injury yourself, try the R.I.C.E. approach:

• Rest. Take a break to rest your hamstring muscles and allow the damaged tissues to repair. Avoid any activity that causes pain, swelling or discomfort. If you have more than a minor muscle strain, your health care provider may recommend that you use crutches to keep your weight off the injured leg.
• Ice. Ice the area as soon after the injury as you can. For the first few days after the injury, keep an ice pack on the injured area for 15 to 20 minutes every 2 to 3 hours while you're awake. Cold reduces pain and swelling. It may also slow bleeding if there's a tear. If you have vascular disease, diabetes or can't feel much in your leg, talk with your care provider before icing.
• Compression. Wrap your leg with an elastic bandage until the swelling goes down. Be careful not to wrap too tightly. Begin wrapping at the end farthest from your heart. Loosen the bandage if the pain increases, the area becomes numb or swelling occurs below the wrapped area.
• Elevation. Sit or lie back with your leg raised while resting. If possible, raise your leg higher than your heart.

Pain medicine you can get without a prescription, such as ibuprofen (Advil, Motrin IB, others) and acetaminophen (Tylenol, others), also might help. After a few days, gently begin to use the injured leg. Your leg's ability to support your weight and your ability to move without pain should get better over time.

You might first talk to your own health care provider. You might be referred to a provider who practices sports medicine or does orthopedic surgery.

What you can do

Make a list that includes:

• Complete information about your symptoms and when they began.
• Information about medical problems you've had.
• All the medicines and supplements you take, including doses.
• Questions you want to ask the care provider.

What to expect from your doctor

Your care provider might ask some of the following questions:

• When did the injury occur and how did it happen?
• Did you feel a popping or tearing sensation?
• Do any movements or positions make the pain better or worse?