Hamstring Strain: Not This Again
While not the most common running injury, hamstring strains have the highest re-injury rate, meaning you’re probably going to have to deal with this again. The biggest predictor for an injury is prior injury to the area, because injury leads to decreased tissue flexibility and coordination/control of the injured tissue and area.
Hamstrings are commonly injured and re-injured in running due to the excessive stretch put on the long head of the biceps femoris during the swing phase. This is because the long head attaches lower on the leg than the rest of the hamstring muscles and carries a larger share of the load. This becomes accentuated in runners with long stride lengths, especially sprinters. Typical rehabilitation for hamstring strains is focused on stretching and increasing tissue length. However, this has been proven to be ineffective. Researchers have found that compared to a standard protocol of hamstring stretching and strength training, a program consisting of agility and trunk stability exercises produced far superior short term and long term outcomes. This training protocol returned athletes to sport in 22 days compared to 37 days of the conventional treatment protocol. The re-injury rate was 0% compared to 55%. Part of this is due to pelvic tilt. When we are not stabilizing our trunk well, our pelvis goes into anterior pelvic tilt (tips forward). This puts the hamstring on a stretch as its pelvic attachment moves up towards the head. This contributes to people feeling like their hamstrings are always tight and they walk around stretching them constantly, paying little attention to their trunk. When we have the hamstring on “pre stretch” it is not surprising that a long explosive stride can lead to a strain of the tissue. Trunk stability training helps decrease pelvic tilt through proper coordination of the deep abdominal muscles.
But let's not throw the baby out with the bath water. This body of research does not mean that there is no use for hamstring stretching. Flexibility of tissues is imperative in injury prevention. Flexible tissue can tolerate larger eccentric (lengthening) loads better than stiffer tissues. Some stretching of the hamstring should be done. And it should be done with both a bent knee and straight knee. A straight knee helps stretch out the long head of the biceps femoris while bending the knee 45 to 90 degrees can help stretch the short head (upper hamstring). Like all stretching, a muscle needs 5 minutes of stretching spread across a week with each stretching session being a minimum of 30 seconds. This stretching does not need to be painful, if 100% is painful stretching, the best results are achieved around 40%.
If you have or previously had an injured hamstring, it is time for you to start looking at your trunk control and agility. A simple test for trunk control is if you can hold a push up position and keep your shoulders level when you pick up one hand. If you feel your body rotate as soon as you lift one hand, you might want to consider doing a little trunk stability work. A simple test for your hamstring flexibility is if you can lay flat on your back with both legs straight then raise one while keeping the other straight. You should be able to create a 90 degree angle with your legs. If you can’t, you may want to consider doing some hamstring lengthening work.
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Wyon, Matthew; Felton, Lee; Galloway, Shaun. A Comparison of Two Stretching Modalities on Lower-Limb Range of Motion Measurements in Recreational Dancers. Journal of Strength and Conditioning Research 23(7):p 2144-2148, October 2009.
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