A hamstring injury occurs when you strain or pull one all of your hamstring muscles. The hamstring is made of the Bicep femoris, semimembranosus, and semitendinosus.
Hamstring injuries most commonly occur with starts and stops quick movements. Common activities such as: soccer, basketball, football, tennis or a similar sport that involves sprinting (running to first base). Hamstring injury(s) can occur in runners and in dancers as well, more from an overuse issue.
Self-care measures include: rest, ice, heat, and over-the-counter pain medications (NSAIDS). This is great symptomatic care, however the problem recurs. Recurring hamstring and muscle injuries need more then just passive care (rest, ice, OTC) they need to be rehabilitated with active myofascial release.
When a muscle has been injured, there are microscopic tears within the muscle. When they repair they become stiff, rough and plastic (non elastic) and stiff. There is also a loss of microscopic blood flow to that area of the muscle. This is evident with the stiffness, painful nodules and lack of strength. There are several different skilled techniques that can be employed to rehabilitate the hamstring muscle.