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Tight Hamstrings Don't Cause Back Pain

For years healthcare providers (including myself) have been told and taught that if a muscle is tight we need to stretch it to return it to what a textbook deems as “normal.”

Research says: “Short hamstrings have been shown in research to be associated with low back pain, thus meaning we need to stretch the hamstrings as a part of the plan to decrease back pain.”

This idea that low back pain is caused by tight hamstrings and stretching them is the solution is one held by A TON of people. I mean.. it makes sense if you look at it with face value.

There’s a BIG problem with this reasoning.

Every heard the saying, "Which came first? The chicken or the egg?"

Are tight hamstrings the chicken or the egg? Are they the cause? Or could they be a result of the pain?


There was a study where they looked at factors that questioned that very thought. Three different groups were looked at: those with "flexible" hamstrings, those with "tight" hamstrings, and those with low back pain.

They measured (degrees of motion) how much the leg would raise up when they tried to stretch it (straight leg raise test) and made sure the pelvis (hips) were in the same alignment and had no influence on the tension. They also asked the person when they "felt" stiffness/pain.

Straight Leg Raise

Here’s what they found:

Those with low back pain had the lowest range of motion via the SLR test (even worse than the ‘tight’ hamstring group).

Ouch, Strike one for my post

The hamstrings in both the "flexible" group and "tight" group showed a similar ‘defensive reaction’ as the they were stretched, but those with low back pain were very different.


Whats a defensive reaction? As you stretch a muscle, your brain actually makes that muscle contract in a way that it is not stretched TOO much. It's all for safety. This is measured by looking at the muscle activity of the muscle (EMG). When muscles contract you can actually measure the signal running through that makes the fibers contract.

So in the "flexible" group and "tight" group the more the hamstring was stretched, the more electrical activity was seen. Makes sense. The further the body senses the muscle being stretched the more it will try to apply the breaks to it stretching too much!

However, those who had low back pain had a very abnormal "defense reaction" and did not have activity in all parts of their hamstrings. The activity also did not increase at the same pace as those who were not in pain.

Also noted that the perception of "stiffness" or when the person felt too much tension/pain was no different in the "tight" and low back pain groups. So remember the decreased flexibility of those with low back pain was was worse than those with ‘tight’ hamstrings.

But this decreased motion was NOT accompanied by increased perception of stiffness.

That means someone with low back pain doesn’t have the same kind of flexibility issues for the same reasons as someone who just has "tight" hamstrings and no pain. The muscles are reacting and behaving differently THUS appearing to be tight.

Those in pain do not have “normal” hamstring flexibility. You can’t just stretch away the back pain. The problem isn’t coming from the hamstrings but instead seems to be a protective reaction of the low back pain itself.

"Tight" hamstrings are a reaction to the pain. The brain is making the hamstrings pull on the pelvis for a reason. Maybe it's a way to try and provide stability to the pelvis? That's a discussion for a different day.

Oh yea If you were wondering: the hamstrings are the egg.

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