What Is a Hamstring Strain?

Three muscles run down the back of the leg, from the thigh to the knee, that help you bend your knee and extend your hip. As a group, they're known as the hamstring.

A hamstring strain — sometimes called a pulled hamstring — happens when one or more of these muscles get stretched too far and start to tear.

Hamstring strains can be mild, with little pain and a short recovery time. Or, they can be severe and need surgery and crutches for weeks.

What Are the Symptoms of a Hamstring Strain?

Most people who strain their hamstring have a sudden sharp pain and possibly a popping or warm sensation at the back of the leg.

Other symptoms of a hamstring strain may include:

• pain in the back of your thigh when you bend or straighten your leg
• tenderness, swelling, and bruising in the back of the thigh
• weakness in your leg

How Is a Hamstring Strain Diagnosed?

A hamstring strain might be diagnosed on the sidelines by a trainer or when you see a physical therapist. Often, you'll also see the doctor for a hamstring strain. The doctor will examine your leg and ask about how the injury happened and how much pain you have.

The exam will help figure out what grade of strain you have:

• Grade 1: This is a mild strain. You may have some pain when you use your leg, but it will be minor and there will be minimal swelling.
• Grade 2: This is a partial tear of one or more of the hamstring muscles. This may cause you to limp when you walk and feel some pain during activity. You might see some swelling and bruising, and some loss of strength.
• Grade 3: This is a complete tear of one or more of the hamstring muscles. You'll feel pain and not be able to straighten your leg all the way, and you'll notice swelling and bruising. It will be very hard to walk, and you might need crutches.

What Causes a Hamstring Strain?

A hamstring strain typically happens as a result of muscle overload, such as when you're running and your leg is fully stretched out just before your foot strikes the ground. When your foot strikes the ground and all your weight is on it, the muscles can get stretched too far and may start to tear.

People who do activities that involve sprinting or jumping (like track and field, soccer, football, lacrosse, basketball, and dance) are more at risk for hamstring strains. These kinds of injuries are also more common during a growth spurt. That's because the leg bones may grow faster than the muscles, pulling the muscles tight and leaving them more likely to get stretched too far.

Some of the more common things that can contribute to a hamstring strain include:

• Not warming up properly before exercising. Tight muscles are much more likely to strain than muscles that are kept stretched and flexible.
• Being out of shape or overdoing it. Weak muscles are less able to handle the stress of exercise, and muscles that are tired lose some of their ability to absorb energy, making them more likely to get injured.
• An imbalance in the strength of the leg muscles. The quadriceps, a group of muscles at the front of the legs, are often stronger and more powerful than the hamstring muscles. When you do an activity that involves running, the hamstring muscles can get tired more quickly than the quadriceps, putting them at greater risk of a strain.
• Poor technique. If you don't have a good running technique, it can increase the stress on your hamstring muscles.
• Returning to activities too quickly after an injury. Hamstring strains need plenty of time and rest to heal completely. Trying to come back from a strain too soon will make you more likely to injure your hamstring again.

What's the Treatment for a Hamstring Strain?

The good news is that most hamstring strains will heal on their own or with some physical therapy.

To treat a hamstring strain, follow these tips:

• For 2–3 days, to help with pain and swelling:
  • Rest the leg and avoid any activities that cause pain.
  • Place ice wrapped in a towel on the area for about 20 minutes several times a day. Do not put ice directly on the skin.
  • Wrap the thigh in an elastic bandage. The bandage should be tight enough to provide gentle support but loose enough that you can fit your finger easily under the edge.
  • Keep the leg above heart level by resting it on a pillow.
• Take pain medicine. Ibuprofen and other non-steroidal anti-inflammatory drugs (NSAIDs) can help relieve pain and reduce swelling in the leg. Some doctors prefer other medicines, like acetaminophen. Talk with your doctor about what to use. Then, follow the directions on the label for how much to take and how often.
• Do stretching and strengthening exercises. Slowly adding some exercises can help to improve your leg's strength and flexibility (and help prevent the injury from happening again). A doctor, athletic trainer, or physical therapist can help determine when your hamstring is ready for these exercises.

If you have a complete tear of one of your hamstring muscles or tendons, your doctor might want you to have surgery to reattach the tendon to the bone or fix the tendon.

What Can Help Prevent a Hamstring Strain?

Keeping your muscles in good shape is the best way to prevent hamstring injuries. Here are some ways to help protect yourself against them (and other sports injuries!):

• Warm up properly before exercise or intense physical activity. Jog in place for a minute or two, or do some jumping jacks to get your muscles going. Then do some dynamic stretching — ask your coach or an athletic trainer to show you how. After you play, do some static stretches where you gently stretch your muscles, holding each stretch for 30 seconds or more.
• Keep your muscles strong and flexible year-round. Get regular exercise and adopt a good stretching program so your muscles don't get a shock when you do an intense workout.
• Increase the duration and intensity of your exercise slowly. A good rule of thumb is to make sure you add no more than 10% each week to the miles you run or the time you spend playing a sport.
• If you feel pain in your thigh, stop your activity right away. If you're worried that you might have strained your hamstring, see a doctor. Then, give it time to heal — returning to sports too soon can make the injury worse.

Not overdoing things is key when it comes to this type of injury. Hamstring strains often come back if a person returns to play too quickly. So follow your doctor's advice and don't push yourself or feel pressure to get back into sports or other activities too soon.