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Pain Profile: Hamstring Strain

The hamstrings are the most frequently strained muscles in the body (Anderson and Parr, 2009, p.547). The hamstrings are strained when rapid or ballistic contractions overload the muscle and a tear occurs within the hamstring muscles, the muscle fascia, or tendons. Many times the hamstrings suffer from recurrent strains and the problem becomes chronic. Treating the underlying causes of hamstring strains can reduce the risk of straining the hamstrings multiple times.

Anatomy

The hamstrings are mainly responsible for hip extension and knee flexion. They are also responsible for some medial rotation of the tibia and the femur. The hamstrings are made up of three different muscles:

  • Semimembranosus – the most medial (toward the middle of the body) of the three hamstring muscles. Attaches on the ischial tuberosity (hip bone), the medial tibia, and the femur.

  • Semitendinosus – a superficial (visible) muscle situated as the middle muscle in the hamstring group. Attaches on the ischial tuberosity (hip bone) and the medial tibia. The semitendinosus is sometimes used to replace the anterior cruciate ligament (ACL) in the knee.

  • Biceps Femoris – As the name implies, the muscle splits into two heads. One head attaches on the ischial tuberosity. The other attaches on the femur. The muscle inserts on the fibula.

Pelvic Positioning

How you orient your pelvis (hips) can put excess stress on the hamstrings and can put you at a higher risk of straining your hamstrings. There are two types of pelvic positions that we will discuss: anterior pelvic tilt and posterior pelvic tilt

An anterior pelvic tilt causes the ischial tuberosity to move superiorly (higher) which causes the hamstring muscles to lengthen. When the hamstrings are constantly in a lengthen state, this causes the resting tension in the muscle to increase. When there is a higher resting tension that creates an environment where the muscle can be strained easily because any sudden increases in muscular force can overload the muscle and cause it to tear. People who walk with an anterior pelvic tilt usually look their stomach is protruding, they have an increased lordosis (curve) in the lumbar spine, and they are always trying to stick their butt out. These people usually have tight hip flexors and quadriceps.

A posterior pelvic tilt causes the ischial tuberosity to move inferiorly (lower) which causes the hamstring muscles to shorten. This environment is also detrimental for the hamstrings because it causes the hamstrings to become tight and reduces the flexibility of the muscle. This reduced flexibility can limit the range of motion at the hip which can lead to more problems in the hip, spine, and knees. Tight hamstrings can be sprained more easily because when the hamstrings become lengthened quickly, tears can occur. People with a posterior pelvic tilt usually look like they are hunched over, have a very flat curve in the lumbar spine, and roll their shoulders forward. These people usually have tight hamstrings, complain of shoulder tightness and have a stiff thoracic spine (upper back).