The hamstring muscles are a group of large, powerful muscles that span the back of the thigh, from the lower pelvis to the back of the shin bone. The hamstring is the important muscle that functions to extend the hip joint and bend the knee joint.
The hamstring is used in many sporting activities, as well as normal daily activities. Sports that commonly cause a hamstring injury are sprinting sports that involve sudden accelerations. These include track and field, soccer, and basketball.
A hamstring injury can also occur as a result of a direct blow to the muscle, such as being kicked in the back of the thigh, or falling on the back of the thigh. Hamstring contusions are different from pulled hamstrings, although they may cause similar symptoms.
Pulled HamstringA pulled hamstring, also called a hamstring strain, is a tear of the hamstring muscle fibers. Hamstring tears are usually graded similar to other types of muscle strains:
- Grade I Hamstring Strain: Mild discomfort, often no disability. Tearing of the muscle fibers is microscopic, essentially stretching the muscle too far. Usually minimal limitations in activity.
- Grade II Hamstring Strain: Moderate discomfort, can limit an athlete's ability to perform activities such as running and jumping. May have moderate swelling and bruising.
- Grade III Hamstring Strain: Severe injury that can cause pain with walking. Muscle fibers significantly or completely torn, potentially requiring surgical intervention. Often patients complain of muscle spasm, swelling, and significant bruising.
Muscle strains and tears most commonly occur because of what is called an eccentric contraction. When an eccentric contraction of the muscle occurs, the muscle is trying to contract while another force (the ground, another player, etc.) is forcing the muscle in the opposite direction. This creates tremendous force on the muscle, and if the force is strong enough, it will tear the muscle fibers.
Symptoms of a Torn HamstringThe symptoms of a pulled hamstring depend on the severity of the injury. The hamstring injury is usually sudden and painful. Other common symptoms include:
- Bruising: Small tears within the muscle cause bleeding and subsequent bruising. The bruise begins in the back of the thigh, and as time passes the bruise will pass down below the knee and often into the foot.
- Swelling: The accumulation of blood from the hamstring injury causes swelling of the thigh. This can make further muscle contraction difficult and painful. Wearing a compressive bandage can help control the swelling.
- Muscle Spasm: Muscle spasm is a common and painful symptom of a hamstring injury. Because of the trauma to the muscle, signals of contraction are confused, and the muscle may be stimulated. If severe, muscle relaxants can help with spasms.
- Difficulty With Muscle Contraction: Bending the knee is often painful after a pulled hamstring, and can even prevent the patient from walking normally. If you are unable to contract the hamstring, the muscle may be completely ruptured.
- You have difficulty walking
- The pain is significant and not relieved with rest
- You think you may have a complete hamstring rupture