When 90 + 90 = 110

Why Improving Your Flexibility Doesn’t Increase Your Muscle Length

I had a client who had been stretching his hamstrings for months to “make them longer.” Even though he was consistent with stretching, nothing changed. That’s because stretching muscles doesn’t actually make them longer.

A Simple Test For You To Try

First, stand on your right leg and lift your left leg out to the side as high as you can. Estimate the angle of your leg. It doesn’t need to be accurate – a rough number will do. Then switch sides and do the same.

Now add both numbers together.

Most people can raise each leg around 70-90 degrees, giving a total of around 140-180 degrees.

Now, try to do the side splits and estimate the angle between your legs.

Your split angle is probably noticeably lower than the combined total from your leg lifts.

If muscle length were the limiting factor, these numbers should be similar, as there are no muscles that cross over both legs. In fact, the splits should have more range, since they require only flexibility, while the leg ligs require both hip flexibility and strength.

So What’s Causing The Restriction?

As your body approaches a position it perceives as unsafe or vulnerable, your nervous system increases tension in the stretched muscles to prevent further movement and protect you from injury, even if more range is physically available.

The split position is a much more vulnerable position than lifting one leg at a time, so your nervous system limits how deep into the split you can go.

If you’re looking to improve flexibility or mobility, you need to teach your nervous system that it’s safe to access these positions and allow the muscles and tissues to stretch — in other words, increase your stretch tolerance.

In most cases, muscle length doesn’t change as you become more flexible.

A Better Way To Become Flexible

One of the best ways to improve flexibility and mobility is to train your muscles in lengthened positions, ideally after stretching. This teaches your nervous system that you can safely control these new ranges.

This has to be done carefully. You are weakest at end ranges and more vulnerable to injury, so loads should be light and performed slowly or isometrically (contracting the muscle without movement).

Applying It In The Real World

I recently worked with a client who couldn’t raise his arms overhead due to very tight lats. He had spent months stretching and foam rolling with little improvement.

So I got him to start strengthening his shoulders at their end ranges. After stretching, he would lie on his back holding a 0.5 kg weight and slowly raise and lower his arm through roughly 150 to 170 degrees of shoulder flexion. It’s similar to lifting the arms overhead, just done while lying down.

Within a few weeks, his overhead flexibility and mobility improved massively.

The muscles hadn’t lengthened. His nervous system had simply learnt that the position was safe and comfortable.