The hamstrings consist of three individual muscles attaching to the pelvic, thigh and leg bones. Hamstring pulls are classified depending on the degree of injury. A grade 1 strain or pull indicates a mild, quick healing injury while a grade 3 strain is a complete tear or rupture of the hamstrings, healing within several months.
Location
The long head of the biceps femoris, the semimembranosus and the semitendinosus originate on the ischium or "sitz bone" of the pelvis. The shorter head of the biceps femoris originates on the posterior-central aspect of the thigh bone and inserts on the uppermost end of the smaller leg bone, the fibula. The biceps femoris insert just below the lateral aspect of the knee while the semimembranosus and semitendinosus insert just below the medial aspect of the knee. Pulls and tears of the hamstrings usually occur at the attachment sites and at the midbelly of the muscles.
Causes
Hamstring strains are caused by overstretching and sprinting activities. Overstretching generally strains the ischial end of the hamstrings. Strains and ruptures of the hamstrings at the distal, or knee end, and in the middle of the belly, are caused by excessive forces or loads. This type of injury results when a person's hamstrings are contracting to bend the knee as the leg lengthens, such as during a sprint.
Features
A major strain to the proximal end of the hamstring induces an immediate, sharp, burning pain. If a person has a minor or grade 1 strain, he may not feel pain and stiffness until the next day. There is also swelling, tenderness, bruising and muscle spasm near the injury, according to Sandra Shultz and colleagues in their book "Examination of Musculoskeletal Injuries."
Treatment
Initial treatments for a hamstring pull include immobilizing and icing the affected area to reduce pain, swelling and inflammation. If there is a complete rupture of the tendon or tear in the hamstring muscle belly, surgery is required. Once pain and inflammation have subsided, electrical stimulation is used to improve protein synthesis. A heat pack and ultrasound are incorporated to increase blood flow, bringing nutrients to the injury and removing waste products, according to Peggy Houglum in her book
"Therapeutic Exercise for Musculoskeletal Injuries." Light stretching and strengthening exercises are used as long as there is no pain. Therapeutic exercises generally need to be continued for as long as six months, according to the American Academy of Orthopaedic Surgeons.
Prevention
Hamstring pulls and tears can be prevented if a person maintains a regular stretching program to improve and maintain the flexibility in her legs. The quadriceps and hamstrings must be worked equally so one muscle group is not more powerful than the other.
References
- "Examination of Musculoskeletal Injuries"; Sandra Shultz, Ph.D., Peggy Houglum and David Perrin; 2005
- American Academy of Orthopaedic Surgeons: Hamstring Muscle Injuries
- "Therapeutic Exercise for Musculoskeletal Injuries"; Peggy Houglum; 2005
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