Hamstring Muscle Injuries
A hamstring injury can be a pull, a partial tear, or a complete tear.
Muscle strains are graded according to their severity. A grade 1 strain is mild and usually heals readily; agrade 3 strain is a complete tear of the muscle that may take months to heal.
Most hamstring injuries occur in the thick part of the muscle or where the muscle fibers join tendon fibers.
In the most severe hamstring injuries, the tendon tears completely away from the bone. It may even pull a piece of bone away with it. This is called an avulsion injury.
Cause & Symptoms
Muscle overload is the main cause of hamstring muscle strain. This can happen when the muscle is stretched beyond its capacity or challenged with a sudden load.
Hamstring muscle strains often occur when the muscle lengthens as it contracts, or shortens. Although it sounds contradictory, this happens when you extend a muscle while it is weighted, or loaded. This is called an “eccentric contraction.”
During sprinting, the hamstring muscles contract eccentrically as the back leg is straightened and the toes are used to push off and move forward. The hamstring muscles are not only lengthened at this point in the stride, but they are also loaded — with body weight as well as the force required for forward motion.
Like strains, hamstring tendon avulsions are also caused by large, sudden loads.
Several factors can make it more likely you will have a muscle strain, including:
Muscle tightness. Tight muscles are vulnerable to strain. Athletes should follow a year-round program of daily stretching exercises.
Muscle imbalance. When one muscle group is much stronger than its opposing muscle group, the imbalance can lead to a strain. This frequently happens with the hamstring muscles. The quadriceps muscles at the front of the thigh are usually more powerful. During high-speed activities, the hamstring may become fatigued faster than the quadriceps. This fatigue can lead to a strain.
Poor conditioning. If your muscles are weak, they are less able to cope with the stress of exercise and are more likely to be injured.
Muscle fatigue. Fatigue reduces the energy-absorbing capabilities of muscle, making them more susceptible to injury.
Choice of activity. Anyone can experience hamstring strain, but those especially at risk are:
Athletes who participate in sports like football, soccer, basketball
Runners or sprinters
Older athletes whose exercise program is primarily walking
Adolescent athletes who are still growing. Hamstring strains occur more often in adolescents because bones and muscles do not grow at the same rate. During a growth spurt, a child’s bones may grow faster than the muscles. The growing bone pulls the muscle tight. A sudden jump, stretch, or impact can tear the muscle away from its connection to the bone
If you strain your hamstring while sprinting in full stride, you will notice a sudden, sharp pain in the back of your thigh. It will cause you to come to a quick stop, and either hop on your good leg or fall.
Additional symptoms may include:
Swelling during the first few hours after injury
Bruising or discoloration of the back of your leg below the knee over the first few days
Weakness in your hamstring that can persist for weeks
Patient History and Physical Examination
People with hamstring strains often see a doctor because of a sudden pain in the back of the thigh that occurred when exercising.
During the physical examination, your doctor will ask about the injury and check your thigh for tenderness or bruising. He or she will palpate, or press, the back of your thigh to see if there is pain, weakness, swelling, or a more severe muscle injury.
Imaging tests that may help your doctor confirm your diagnosis include:
X-rays. An X-ray can show your doctor whether you have a hamstring tendon avulsion. This is when the injured tendon has pulled away a small piece of bone.
Magnetic Resonance Imaging (MRI). This study can create better images of soft tissues like the hamstring muscles. It can help your doctor determine the degree of your injury.
Great Lakes Physical Therapy
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