About twenty years ago, I stumbled onto something while working with people who had lower back pain.

Almost all of these folks complained of tightness in their hamstrings.

Some felt tightness at rest but many of them complained that when they moved, bent over to pick something up or tie a shoe, their hamstrings felt much tighter than usual.

A common attitude within physical therapy about lower back pain is that it’s often caused by tight hamstrings and the solution is to stretch the muscles.

I was taught that approach in PT school, had encountered it several times in professional seminars I attended over the years, but I had very little success with stretching hamstrings in people with lower back pain. It didn’t improve their pain nor their flexibility.

Are Your Hamstrings Really Tight?

Well, as it turns out, tight hamstrings, while a consistent finding in people with lower back pain, are not a cause of it. ((Raftry, S. M. and P. W. Marshall (2012). “Does a ‘tight’ hamstring predict low back pain reporting during prolonged standing?” J Electromyogr Kinesiol 22(3): 407-411.))

The restriction of motion, in fact, is not from actual muscle stiffness. The loss of flexibility is due to something referred to as stretch intolerance.

Stretch intolerance is governed by the nervous system. In the presence of lower back pain, your nervous system goes on high alert. This increases sensitivity to stretch and your perception of stretch ^[1]https://www.sciencedirect.com/science/article/abs/pii/S000399930116613X

If you measure muscle activity of the lower back and hamstrings with electrodes during a forward bend, normally, at the end of your available motion, your back muscles and your hamstring activity will cease.

But the hamstrings only go quiet after your lumbar spine has completed its full motion.

And here’s the issue.

If you have lower back pain, when you bend forward, nines out of ten, your lower back motion is not normal. You rarely move through the full range available to you because, well, you hurt or your joints do not move properly.

The result is that your hamstrings don’t turn off and they feel tight.

Adjusting Hamstring Tightness

I discovered this phenomenon after I gave a a client an exercise to perform to help relieve his lower back pain. His hamstrings were tight (measured while lying down) – very tight.

He did the exercise for about ten minutes. I then had him lie down and I measured his hamstring flexibility again.

It almost doubled. And his forward bending was much better and his sense of tightness improved.

Bottom Line

Being flexible is one of the keys to feeling younger while you get older. Hamstring tightness is not always due to muscle stiffness and the solution is not always stretching.