What Stretches When You Stretch?

Let’s take the bend-over-touch-your-toes example. Let’s say that you can reach down to about three inches above the floor and your hamstrings feel as tight as a drum.

So, you do some stretching for a while and now your fingertips hit the floor.

What happened?

Did the muscles get longer? Is that why you can touch the floor?

Even without any science, we know your muscles don’t get longer from stretching. We can tell just by looking at them.

The hamstrings attach from one point to another and that distance is fixed. So, if the muscle(s) physically lengthened from stretching, then when you stand up, your hamstrings would look wavy.

When I was in high school, I was a high-jumper. My coach told me I needed to be more flexible so I stretched. A lot. Eventually, I could sit on the floor, legs apart and place my chest flat on the floor with no problem.

Today, I’m doing good to sit on the floor, legs in front and reach my toes.

My muscles are the same length as they were many moons ago. My flexibility or the pliability has changed.

Muscles are similar to springs. You pull on a spring and it lengthens. When you release the tension, it returns to the original length. This is what happens with muscles.

Flexibility is the passive range of motion of a joint or joints.

So, when you bend over to touch your toes, you’re using a certain amount of flexibility actively, at several joints, during the movement and that is referred to as mobility.

Mobility is an active process while flexibility is passive.

One way to improve mobility is to improve flexibility. And stretching is the usual tactic to improve flexibility.

Although resistance training can also improve mobility by improving flexibility.^[1]Morton, S. K., Whitehead, J. R., Brinkert, R. H., & Caine, D. J. (2011). Resistance training vs. static stretching: effects on flexibility and strength. J Strength Cond Res, 25(12), 3391-3398. … Continue reading

Huh?

How does strengthening a muscle improve its flexibility?

Because the main governor of flexibility is our nervous system.

I discovered this when I was an intern at Rancho Los Amigos Hospital. I worked in the neuro department. My clients had various neurological diagnoses and one of the clinics I worked in helped people with traumatic brain injuries regain flexibility in the lower leg so they could walk more easily.

Sometimes a brain injury can cause certain muscles to contract or tighten up. This makes the muscle stiffer, much like a really stiff spring, and makes movement much more difficult.

The muscle group most often affected was the calf muscles. When you try to walk with a calf muscle that’s way too tight, it’s almost impossible.

No amount of stretching changed this because the nervous system had established a new “normal” and it’s the nervous system that regulates how much stretch can take place. There are receptors in the muscle and tendons that monitor the starting point,  rate, and the magnitude of stretch. As you stretch the muscle and approach a certain rate or tension level, the nervous system essentially says, “Ok, that’s enough” and the muscle resists you.

But, when the nervous system has been damaged like in a brain injury, the signaling system is wrecked. For our clients at Rancho, the slightest stretch set off a lot of tension and resistance.

How we overcame this was by doing two things. We injected the muscles with what was essentially botox. This temporarily paralyzed the muscles. Then, we applied a cast to the lower leg placing a slight amount of tension on the calf muscles. The botox would eventually wear off but we had changed the starting point of the muscle and the nervous system recalibrated.

We hacked the nervous system making it think that this new position was just fine.

The client returned and we repeated the procedure. It would take many weeks to get the muscle close to normal or regain enough flexibility so walking would be more comfortable and more efficient.

When you stretch, you teach the nervous system a new normal but you have to do it in a way that doesn’t set off alarms and increase the tension.

The primary alarm in stretching to the nervous system is pain. When the stretch hurts, you won’t gain much from doing it. However, there’s a difference between pain and discomfort.

And this is where things get tricky.

For stretching to be effective, it will be uncomfortable and some people interpret this feeling as pain. So they stop stretching as soon as it feels uncomfortable and see little progress.

For me, there are a number of yoga poses that are uncomfortable because I don’t have the flexibility and mobility to perform them with ease like this one that is sometimes called  “eye of the needle”.

eye-of-needle pose

She looks peaceful. I look like I’m in a wrestling match and losing.

My hip and lower back flexibility aren’t great enough to do this pose without a lot of strain. So, I have to modify it, use less motion and breathe slowly to allow my nervous system to “learn” the position.

And there are a few yoga poses for me that are painful. The ones that are painful, I have to figure out how to improve the flexibility in another way, a way that might be uncomfortable but not painful. Then, I can come back to the poses and perform them again with greater success.

So how do you differentiate between uncomfortable and pain?

For me, uncomfortable during a stretch is an annoying, tight, pulling sensation. I don’t like it but I can tolerate it. It goes away as soon as I release the tension. Pain is a more alarming, sharp, piercing, almost a tearing sensation that I want to get out of right away and sometimes doesn’t go away after releasing the tension.

Back to the idea that muscles are like springs, the nervous system decides how “tight” the springs are and both stretching and resistance training reduce the tightness. This is why your movement becomes easier as you get stronger. You have strong, springy springs for muscles.

Thanks for reading.

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