Protective Muscle Reflexes And The Art Of Stretching Or Lengthening


“Stretching or lengthening is a conversation you have with a muscle, not something you do to a muscle.” FitOldDog, September, 2012, whilst talking to himself and running trails.

re·flex/ˈrēˌfleks/ Definition from Google:

An action that is performed without conscious thought as a response to a stimulus.

Hi folks,

Muscle detection system for length and tension, proprioreceptors

Proprioceptors are muscle protection systems that determine length and tension.

I live with a nurse, as a result of which from time to time I receive random questions about how the body works or what a particular acronym might mean. I don’t mind my research background being used in this way as I learn a lot, some dredged up from the past and some looked up and entirely new. Recently, I was asked, “What does BNP stand for again?” I said, “Something Natriuretic Peptide,” but where my brain found that one I had no idea, and I’d completely forgotten what it did and what the ‘B’ stood for, except I suspected that the heart was involved, so off to Google! Yep, BNP is Type B Natriuretic Peptide, which is released by the major chambers of the heart, the ventricles, to protect these muscular pumps from being overstrained – when the load becomes too much they release the chemical BNP and this causes peripheral resistance in the circulation of blood to decrease, taking the load off of the heart before tears, strains and failure of this muscular pump should occur. This is a typical muscular protective reflex. The body is full of these systems, designed to keep the body machine working within safe limits. In the case of BNP, the reflex is chemical or hormonal.

Stretch reflex arcs and reciprocal inhibition prevent opposing muscle groups ‘fighting’ each other, and this is the basis of ‘Active Isolated Stretching.’

Each muscle in your body is provided with such local protective systems, including proprioceptors, neural (nervous system based) reflexes that reduce the risk of muscles being over stretched or subjected to undue strain, which would lead to tears and maybe severe damage. These reflexes underlie the method of Active Isolated Stretching (A.I):

“The underlying theory behind A.I. is that if a muscle is stretched too far, too fast, or for too long, it elicits a protective action known as the myotatic reflex, causing it to automatically and ballistically recoil in an attempt to prevent the muscle from tearing. This occurs about three seconds into a stretch.” Quote from an interesting article by Jim and Phil Wharton in Running Times.

An understanding of another important reflex which reduces the tendency of opposing muscle groups to ‘fight each other,’ is also one of the underpinnings of the logic behind Active Isolated Stretching, and again to quote from the article by Jim and Phil Wharton:

The other key to A.I. [Active Isolated Stretching] is to contract the opposing muscles to allow the target muscle to relax. For example, when stretching the hamstrings, the quadriceps muscles on the front of the leg are contracted, relaxing the hamstrings and making them more susceptible to stretching.”

As a serious enthusiast of the value of The Feldenkrais Method for athletes, especially older athletes, or people wishing to undertake a program of safe exercise for better health, I agree with what my instructor, Karen, told me, that our goal is to lengthen muscles not stretch them. Stretching implies force, and the very word will encourage the neophyte to apply too much force, which will lead to micro-tears that do more harm than good. It is much better to apply an understanding of the reflexes referred to above, than brute force.

Remember, after you learn to gently stretch or lengthen a muscle, any tightness that you are trying to fix comes from weakness. So make sure you strengthen the muscle to the level appropriate to the intended load. This is why weight room work is such a critical part of any training season.

-k @FitOldDog


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Disclaimer: As a veterinarian, I do not provide medical advice for human animals. If you undertake or modify an exercise program, consult your medical advisors before doing so. Undertaking activities pursued by the author does not mean that he endorses your undertaking such activities, which is clearly your decision and responsibility. Be careful and sensible, please.