Hamstring Strains: Why They Occur And What To Do About Them

By: Dr. James Cassell, PT, DPT

Hamstring strains are a very common injury, typically occurring during running sports. The hamstrings are a group of 3 muscles on the back of the thigh: biceps femoris, semitendinosus and semimembranosus. They flex (bend) the knee and also extend the hip, additionally, they act to decelerate the knee during running. Hamstring injuries can range from a minor strain or pull, to a complete tendon rupture, with treatment depending upon the extent of the damage.

A grade I strain of the hamstrings occurs when the hamstrings are overstretched, but no tearing occurs to the muscle fibers. This is the most common injury to the hamstrings, and typically occurs from running, especially if the hamstrings aren’t sufficiently warmed up. The recovery for a grade I hamstring strain can take anywhere from 1 to 3 weeks, with treatment focusing on decreasing pain, improving hamstring flexibility and restoring normal dynamic function through the hamstrings entire range of motion.

Improving hamstring flexibility is very important for maintaining healthy function and for preventing re-injury, which tends to happen with hamstring strains. Static stretching; which is when you hold a stretch for a given duration (30-60 seconds) without any further movement, is used to cause permanent changes in tissue length – meaning that this type of stretching actually increases flexibility. Dynamic stretching; such as doing high kicks and walking hamstring stretches, are used as a warm up, as these movements prepare the hamstrings to be quickly stretched, as they would be during activity/sport.

In addition to stretching and proper warm up, eccentric strengthening of the hamstrings is essential. The eccentric contraction of a muscle is when the muscle is being elongated against resistance. An easy way to think of this, is when you are doing a biceps curl, lifting the weight up is the concentric biceps contraction, and lowering the weight is the eccentric biceps contraction. For the hamstrings, the eccentric contraction occurs when the knee is being straightened. This is important, because while running, the hamstrings eccentrically contract to slow down the knee while it is being straightened and again when the front foot hits the ground during running. Eccentric strengthening would include exercises such as Romanian deadlifts, lying hamstring curls and physioball bridge hamstring curls, with a 5 second lowering portion of the movement. Ideally, hamstring strength would be at least 60% of quadriceps strength, otherwise the quadriceps will overpower the hamstrings during running.

Grade II hamstring strains are more severe than grade I, in that there is some degree of tearing of tendon/muscle. If you strain your hamstring, and it starts to turn purple, you have at least a grade II strain, as the blood which causes the bruising is only present due to a structure tearing – you’ll also probably be limping. Grade II strains can take up to 2 months to recover, as more healing needs to occur than with a grade I. The treatment is similar to a grade I, in that flexibility and eccentric strengthening are focused on, however the aggressiveness of a treatment program is dialed back significantly, as immediately doing dynamic stretching may progress tearing or re-aggravate symptoms.

Another component to treatment is soft tissue massage, either in the form of deep tissue massage, Graston TechniqueⓇ or Active Release TechniquesⓇ. This is important for grade II strains, as it helps to prevent scar tissue from adhering to surrounding tissue. Scar tissue will develop regardless, as that’s part of the healing process, but we want to keep the scar tissue as mobile as possible, as it is a thicker, less elastic type of tissue, which we do not want to be present in a muscle which needs to be moving quickly.

Lastly, grade III hamstring strains are actually complete ruptures, which can occur to 1, 2 or all 3 of the hamstrings. If this occurs, the hamstrings will turn purple and you may be unable to walk due to the pain and inability to move your leg. This injury requires surgical intervention to re-attach the hamstrings. The recovery for a hamstring rupture can take up to 1 year to restore full dynamic function, with many surgeons having different post-operative protocols to follow.

If you sustain a hamstring injury and not sure the level of injury, it is always best to seek medical attention. A physical therapist would be able to diagnose the severity and recommend any imaging that may be necessary, especially if there is a complete rupture or suspicion of one. They would also be able to help with the recovery and potential re-injury of a grade I or II hamstring strain.

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