Hamstring Injury: Treatment & Prevention

What Are the Hamstrings?

The hamstring muscles are the three large muscles on the back side of the thigh. Medically, they're known as the semimembranosis, the semitendinosis, and the biceps femoris muscles. These muscles span the thigh, crossing both the hip and the knee. They originate or begin at just below the buttocks, arising from the bone on which we sit (the ischium). They connect by means of their tendons onto the upper parts of the lower leg bones (the tibia and the fibula).

The origin of the word "hamstring" comes from the old English "hamm," meaning thigh. "String" refers to the characteristic appearance and feel of the tendons just above the back of the knee.

What Is the Function of the Hamstrings?

The hamstring muscles bend (flex) the knee. They also act to straighten or (extend) the hip (as in the motion of moving the thigh backwards). Surprisingly, these large muscles are not very active with normal walking or standing. However, they are extremely important in power activities such as running, jumping, and climbing. Thus, sedentary individuals can get by with quite weak or de-conditioned hamstrings, whereas athletes and very physically active individuals absolutely depend on healthy, well-conditioned hamstrings.

The power advantages of strong hamstrings have been known for a long time. In times past, a sword-wielding knight would disable an opponent by a slice across the back of the thigh. Cruel masters were known to have severed the hamstrings of domestic slaves or prisoners in order to make escape less likely. The origin of the term "hamstrung," meaning to have been crippled or held back, is derived from these practices.

Hamstring Injury: How Does It Happen?

Injuries to the hamstring group of muscles can range from a minor strain (often called a pulled hamstring or hamstring tear) to a major rupture. Given the function of these muscles, it should not be surprising that serious injuries most frequently occur in the athletically active. Mild hamstring injuries in sedentary people tend to heal fully with only minor aggravation. On the other hand, in power athletes, hamstring injuries can be severe and debilitating. Many a promising or successful athletic career has been limited if not ended by such injuries. One such memorable image is that of Yankee baseball star Mickey Mantle sprawled in agony at first base, having sustained a massive hamstring tear while lunging to beat out a throw.

Hamstring injuries usually occur with sudden lunging, running or jumping. Oftentimes a "pop" is heard or felt by the injured athlete. A variable amount of pain is experienced. The athlete is usually unable to continue and oftentimes cannot even stand.

Examination of the individual reveals spasm, tightness, and tenderness. With more severe injury, swelling and a black and blue or bruised appearance will follow. Tears and strains most often occur at the middle of the back of the thigh where the muscle joins its tendon or where the hamstring attaches at the base of the buttocks.