The Truth About Stretching Part 1 – What you thought you knew, and what you ought to know.

Written by Philip Walter on Mar 18 at 12:44 am in hatha yoga, itBODYnature, stretching, The Truth About Stretching

Photo courtesy of j / f / photos

Okay, I have been reading a lot lately in physical fitness literature about how stretching is not as fantastic for your body as once thought. When I took basic health in college, static stretching was taught as an integral part of a complete physical fitness plan. Not sure what that curriculum looks like today, but a greater understanding of the stretching phenomenon has forced me over the years to rethink how it fits into my workouts.

I know what you’re thinking – But Philip, you do a lot of yoga … and “flexible” is part of your blog’s tag line, for cyrin’ out loud. Surely you’re not about to talk smack about stretching, are you?!

Well, yes I am, but it’s not because all forms of stretching are inherently bad for your body, it’s because the efficacy and proper methodology of stretching are so widely misunderstood, especially when it comes to yoga posture practice.

In Part One of this two-part series, I want to introduce you to the stretch reflex and debunk one of the biggest myths about stretching. I’ll warn you up front, this one does get a little technical, but if you stick with it, I guarantee you’ll be a smarter stretcher for it.

Proprioception and Proprioceptors

Your nervous system constantly monitors the relative position of your body’s structures through a set of processes known collectively as proprioception. Proprioception means “sense of self,” and this sense of self is maintained by a set of feedback loops. Electrical impulses are fed back from specialized sensors called proprioceptors, which live nested in muscles, tendons, ligaments, and joints throughout the body. They provide your brain with an ongoing stream of information about muscle length, joint angle, and muscle tension. This data helps you maintain your balance and avoid injury, among other things.

The Stretch Reflex

The stretch reflex (also called the “deep tendon” or “myotatic” reflex) is a negative feedback loop that allows you to keep a given muscle at a desired length. This reflex is triggered by proprioceptors called muscle spindles, which are located throughout the body of a muscle. As the muscle spindles in a given muscle are stretched, they send louder and louder signals to the brain to contract the muscle being stretched, so as to avoid lengthening it beyond the desired degree.

This is how you manage to, for example, hold a glass steady as you fill it with water. You need to keep your elbow and wrist joints at the proper angles so that the glass doesn’t spill, and in order to do that, the muscles that control those joints need more or less to maintain a steady length as the weight of the water filling the glass increases. What happens is that your bicep begins to slowly lengthen as the water makes the glass heavier. This causes the muscle spindles in your bicep to talk more loudly to your spinal cord, which then (as a result of the stretch reflex) tells your bicep to contract, maintaining its desired length to avoid spilling the water in the glass.

This interaction is going on all the time, and since your muscles are always under some degree of stretch, no matter what your posture, the stretch reflex is also responsible for the steady level of tension in muscles we call muscle tone.

Pumping Up the Volume

This myotatic stretch reflex has a volume knob. It is turned up and down largely according to the level of gamma motor neuron activity (though there are other factors), which increases with the difficulty of the movement being undertaken. As your movements become faster, more forceful, or more precise, the gain goes up on this volume knob, and so does the contractile response to a given stretch. This means that the same amount of stretch is going to elicit a stronger contraction when the stretch reflex’s volume is cranked, which it is if you’re performing a challenging workout, or playing sport.

The Real Cause of Injury

All this information comes together to debunk one of the primary logical fallacies people make when touting the value of stretching. It is automatically assumed that muscles and connective tissues tear because they are simply stretched beyond their maximum threshold and shred or snap like a rubber band. This, however, is a physiologically incomplete picture of what happens during such an injury.

It is not simply maximum stretch, but the combination of muscle tissue stretching on the one hand and muscle tissue contracting (as a result of the stretch reflex) on the other that causes injuries like sprained ankles and torn muscles. This is why martial arts champ and fitness guru Scott Sonnon says “the goal of allowing the organism to be permanently flexible is met through the regulation of muscular tension to govern the stretch reflex.”[1]

So, how do we do this? I’ll cover some practical ways to get a better and safer stretch in the second installment of this series. Feel free to subscribe to my feed via rss or e-mail so you don’t miss it. Till then, please comment below if you have any thoughts or questions on the material above.

Thanks as always for reading!


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