A hamstring strain (also known as a pulled hamstring) is an injury that results from damage to the hamstring muscles at the back of the thigh. This muscle injury occurs frequently in athletes. It is particularly widespread among athletes in sports requiring intense sprinting e.g. track, basketball, football and soccer.
Fortunately, most hamstring strains are treatable using conservative, non surgical approaches. However, in addition to the traditional R.I.C.E. treatment protocol, athletes who have suffered a hamstring injury are more liable to experience another such injury at some point in the future. To reduce the likelihood of reccurrence, athletes should pursue exercise programs to stretch and strengthen the hamstring muscles as well as those of the gluteal region (buttocks).
Although we usually refer to the hamstring as though it was just a single muscle, it is actually a group of three muscles that run along the back of the upper leg. The muscle group runs from the hamstring tendons just below the pelvis, cross the knee joint and end in the lower leg.
The hamstring muscles play a primary role in activities involving bending the knee or extending the leg straight back. These two movements are key to effective sprinting, which is why track sprinters are among the athletes most likely to experience a hamstring injury.
Types Of Hamstring Strain
All hamstring strains belong to one of the following three categories:
A grade 1 or mild hamstring strain, involving a “pull” or overstretching of the hamstring with no tearing;
A moderate, or grade 2, injury in which there is a partial tear of the hamstring;
A grade 3 strain, with a complete tear of the hamstring. Usually the tendons separates completely from the adjacent bone. It may even take a piece of bone with it – known as an avulsion injury.
Causes Of Hamstring Strains
At the most fundamental level, these strains are due to overloading of the muscles of the hamstring group.They usually occur when the muscle extends while it is weighted or loaded – a movement that doctors call an “eccentric contraction”.
When you sprint, your hamstring muscles undergo eccentric contraction as you straighten your back leg and use your toes to push off. In this position, your hamstring muscles are not only lengthened but loaded with your body weight as well as the force you will need to move forward.
The factors that can increase your risk of experiencing a hamstring strain are:
Tightness of your hamstring muscles, which makes them more vulnerable to damage due to overstretching;
An imbalance between the strength of the opposing quadricep muscles and that of the hamstring muscles. If the quadricep muscles are stronger than those of the hamstring group, the hamstring muscles may become fatigued quicker than the quadricep muscles. As a result, you may unintentionally overload your hamstring muscles and then experience a strain;
Weak or fatigued hamstring muscles. If these muscles are underdeveloped or tired, they are more easily overworked and a muscle strain is more likely to occur;
Extensive involvement in activities that place high demands on the hamstring muscles can lead to a strain. Such activities can include sports like football, soccer or rugby. Other activities that can increase the risk of a hamstring injury are sprinting or dancing;
Being an adolescent athlete undergoing a growth spurt with bones occasionally growing faster than the corresponding muscles. In this situation, the faster growth of the bone can cause the muscle to become overstretched. When this happens, a sudden jump or short sprint can be all that is needed to pull the muscle or even tear it away from the adjacency bone;
Another factor that can increase your risk of experiencing a hamstring strain is having had one previously. If your previous injury was not properly treated (and if you have not completed a physical therapy program as part of your rehabilitation) you are liable to re-injure your hamstring.
The typical symptoms of a hamstring strain include some or all of the following:
A sudden sharp pain at the back of the thigh at the time the injury occurs. This may be accompanied by a snapping or “popping” sound or feeling in the same area;
This pain will usually cause you to stop in mid stride and immediately start limping or even to fall;
Pain and swelling at the back of the leg during the next few hours or days. The area may also feel tender to the touch;
A contusion or bruising at the back of the thigh (again, developing over the next few days or hours);
Continuing weakness in your hamstring and difficulty bending your knee. For a grade 3 sprain, this weakness and loss or range of motion may be so severe that you may experience difficulty walking or even (in some cases) standing.
If you experience some or all of these symptoms, we would suggest making an appointment with a doctor (preferably one with a sports medicine background). The doctor will be able to examine the injury and diagnose the cause of the injury.
To understand the nature of your injury, your doctor may ask how it happened. He or she will also perform a physical examination of your hamstring for discoloration or other evidence of bruising. Your doctor may also feel or “palpate” several places at the back of the thigh and ask you about the pain you feel as a result. This will help him or her to understand the severity of the injury.
Your doctor may also request either an X Ray or MRI scan to help determine the severity of the hamstring injury. X Rays are particularly useful in detecting avulsion injuries. They can reveal the damage caused by the tendon that has detached from its adjacent bone.
If the doctor concludes that you have a grade 1 or 2 hamstring strain, he or she will likely suggest a conservative non invasive treatment plan. Mild or moderate strains usually respond well to this approach, and surgery is usually not required.
Conservative Treatment Of A Hamstring Strain
As a conservative treatment plan for your hamstring strain, your doctor may recommend following the R.I.C.E. protocol:
Resting by refraining from strenuous physical activity for a period. To completely rest the injured hamstring, your doctor may recommend that you avoid putting your weight on it by using crutches;
Applying Ice or a Cold Compress to the affected area. For best results, do this for period of 20 minutes or so, and at intervals of 2-3 hours. This will help with control of pain and swelling. Be careful to wrap the ice or cold compress in a towel or some other insulating material. This will avoid direct contact with the skin and possible skin damage;
Elevating your thigh above heart level as much as possible e.g. by resting it on a pillow when you are lying down. This will help drain stale blood from the injured area. That blood will be replaced with fresh, nutrient rich, blood that will promote faster healing of your hamstring strain;
If your pain and swelling is severe, your doctor may prescribe a non steroidal anti inflammatory drug (NSAID) such as Ibuprofen for additional relief. However, you should be sure to ask about any side effects from the use of this type of medication;
Once your pain and swelling have started to recede, healing is underway. Your doctor may refer you to physical therapy involving stretching and strengthening exercises for your hamstring and gluteal muscles.
Once your pain has completely disappeared and you feel the same strength in the injured leg as you do in the other one, you can have a discussion with your doctor about when you can return to sports activity.
For a grade 3 injury, especially one involving avulsion, the above conservative approach will likely not work. Consequently, you may need to undergo surgery to correct your hamstring strain.
If avulsion has taken place, the surgeon will need to reattach the hamstring tendon to the bone using stitches or staples. Scar tissue may also need to be removed as part of the procedure.
Even without avulsion (i.e. if there is a tearing of the muscle itself) surgery may be necessary to repair the muscle damage.
The recovery time for a hamstring strain depends (obviously) on the severity of the injury and on your level of fitness. A mild strain may require just a few weeks of rest before you can return to normal activity.
However, a grade 3 injury including avulsion may require 3 or even 6 months for a full recovery. You should ask your doctor for advice on the timing of your return to regular physical activity.