The hamstrings are three powerful muscles that travel along the back of your thigh. They are the semitendinosus, the semimembranosus and the biceps femoris muscles. They help bend your knee and extend your leg behind your body. Because these muscles handle high loads of stress, they are susceptible to stretching and tearing. This is called a muscle "strain." Hamstring strains are common among runners, dancers, and athletes who play sports that require sudden starts and stops.
Hamstring strains can range from mild to severe. Mild strains involve an overstretching of the muscle fibers. This is commonly called a "pulled muscle." Moderate strains may involve a partial tearing of the muscle or the tendon that attaches it to the bone. These types of strains are treated with rest, ice, compression and elevation. You healthcare provider may recommend immobilizing your leg while it heals, and you may benefit from physical therapy.
The most severe strains involve a complete tear of the muscle or tendon. The tendon may tear away from the bone. It may even break off a piece of bone at the attachment point. These types of injuries often require surgery. You will need physical therapy as part of your rehabilitation.
Hamstring injuries, even severe ones, can be treated effectively. But if you have had a hamstring injury, you may have an increased risk for injuring the muscle again in the future. Follow your healthcare provider's instructions to make sure you heal correctly.