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Fact Check: Will Strengthening Your Tight Hamstrings Make Them Tighter?

in YogaDork Ed

strength-kidweight
by Jenni Rawlings

In any given yoga class, we are bound to practice an abundance of poses which stretch our hamstrings and relatively few that actually strengthen them. This rarely-discussed imbalance in yoga sequencing tends to occur for two main reasons.

First of all, there simply aren’t that many yoga asanas out there which strengthen the hamstrings in a meaningful way. Even if a yoga teacher wanted to focus specifically on hamstring strengthening in a particular class, she would have very few options in the traditional yoga pose canon from which to choose. Second, yoga teachers are well aware that many of their students have “tight” hamstrings, and there is a conventional belief in the yoga world (and in the fitness community in general) that it is not advisable to strengthen “tight” muscles because it will only make them tighter.

Today we’ll focus on the latter of these two issues: the idea that we should avoid strengthening our tight muscles because they are already tight. This is a very common and completely understandable belief among yogis. After all, one of our foundational goals in our yoga practice is to cultivate balance in our body. With this goal in mind, one of the last things we would want to do is create more tightness in an area that was already tight-feeling to begin with.

BUT WHAT DO WE MEAN WHEN WE SAY “TIGHT”?

strength-hamstretchSurprisingly, the widely-used term “tight” often means quite different things to different people. The following are all possibilities for what someone could be describing when they say they are “tight”:

-they aren’t able to stretch very far in a given direction
-their actual experienced sensation of their muscles when they stretch is “tight”
-the general, perpetual state of a specific muscle or group of muscles in their body is tight (i.e. “my hip flexors are tight from sitting so much”)
-they experience a vague sense of achiness or discomfort somewhere in their body (i.e. “my low back feels stiff and tight”)
-something else entirely :)

The reality is that there is ultimately no science-based definition for the word “tight”. The term is a very subjective one that each person experiences uniquely in his or her own body. This lack of an actual physiological definition for “tight” throws into question the very basis for the “strengthening tight muscles makes them tighter” belief. If there is no clear mechanism for what “tight” is, any rule about the body based on this concept begins to lose its meaning.

ARE TIGHT MUSCLES SHORT MUSCLES?

Although the notion of “tight” lacks a physiological definition, one commonly-shared belief about tightness is that the muscle(s) in question are shorter than they should be, and the natural solution to their “tightness/shortness” is to therefore lengthen them back out by stretching them.

strength-brainThis has been the dominant paradigm regarding stretching and “tight” muscles in the yoga world (and the fitness community in general) for many years. In my 2-part blog post series Stretching Is In Your Brain, I discussed that in contrast to this “short muscles that need to be lengthened” idea, a more updated, research-based perspective on stretching is the notion that our body’s flexibility is instead governed by our brain and central nervous system via a mechanism called stretch tolerance. [See study.] In summary, our inflexibility is not due to physically short muscles – it is instead due to our brain putting the brakes on our movement because it perceives that any deeper of a stretch will not be safe for us (and it’s probably right!) The “tightness” feeling that we experience at the end of our stretch is not the feeling of short muscles reaching the end of their length, but of an output of our brain in response to our stretch designed to signal us to stop the movement.

Isn’t this a fascinating and possibly mind-bending new way to approach the body in terms of stretching and our yoga practice?

STRENGTHENING THOSE TIGHT HAMSTRINGS

The hamstrings muscle group: biceps femoris, semitendinosus, & semimembranosus. (Image courtesy Real Bodywork, Inc.)

The hamstrings muscle group: biceps femoris, semitendinosus, & semimembranosus. (Image courtesy Real Bodywork, Inc.)

Paradigm-shifting aside, let’s return to the main topic of this article, which is the common belief that strengthening a tight muscle will make it tighter. In the same way that we tend to believe the outdated idea that our inflexible muscles are “short”, we also tend to believe that strengthening a muscle will physically alter that muscle so that it becomes shorter.

For example, the hamstrings might be the number-one-cited area of “tightness” in the average body. (But remember that “tightness” is a non-specific term without true scientific meaning.) If we believe that our hamstrings are “tight” because they areshort, and if we also believe that strengthening muscles will physically shorten them, then there is no way that we would ever think that strengthening our short, tight hamstrings is a good idea. Tight plus tight equals more tight, right?

strength-muscleIn addition to the example of the hamstrings, here are a few other areas of the body to which we often apply this same logic:

-our hip flexors are short from too much sitting, so we shouldn’t do hip flexor-strengthening moves

-our spines are rounded-forward (hyperkyphotic) from too much slouching, so we shouldn’t practice traditional abdominal work because it would shorten our abdominal muscles and pull us into more of a slouch

-our calves tend to be tight from high-heel (and other positive-heeled shoe) wearing, so we wouldn’t want to strengthen our calves because it would further tighten them

These arguments would absolutely make sense if we were still operating under the paradigm of physically-short muscles that we lengthen back out by stretching. But in the same way that we now understand that stretching a muscle doesn’t make it “longer”, we have also learned that strengthening a muscle does not make it “shorter”. Or to be more accurate, there is very little (if any) evidence to support the idea that strengthening a muscle causes it to structurally change so that its resting length becomes shorter.

As counterintuitive as it may seem (believe me, I know!), strengthening muscles does not “tighten”, “stiffen”, or “shorten” them – it doesn’t decrease their flexibility in any way. [See study.] In fact, if we strength train our muscles eccentrically (which means that our muscles are active as they lengthen), this has been shown to actually increase their flexibility. [See study.] So not only does strengthening a muscle not physically shorten it, but if done correctly, it can increase its stretch tolerance. This seems so contrary to popular thinking, but once we understand that our muscles only do what our powerful, communicative, and dynamic central nervous system tells them to do, these concepts begin to make more intuitive sense.

One important note is that while strengthening doesn’t stiffen our muscles, it will stiffen up our connective tissue (which is distinct from, although interwoven with, our muscle tissue) – but this is actually a desirable outcome. As I discussed in Stretching Is In Your Brain Part 2, we want our connective tissue to be stiff so that it can be strong, resilient, and less vulnerable to injury.

IN CONCLUSION…

In circling back to the overarching question of this article: no, strengthening your tight/short hamstrings (or any other muscles) will not make them tighter/shorter. But it will make the connective tissue of your hamstrings stronger and less prone to injury. This is especially relevant for yogis, given the high incidence of hamstring pulls and strains we experience in the yoga community as a result of the traditional sequencing of lots of hamstring stretching and very little strengthening. With this new knowledge about muscle physiology in mind, we should feel encouraged to strengthen any area of our body we might have previously been avoiding because we were afraid it would “tighten” up as a result. This change in approach will represent a path toward greater body awareness and the true balance that so many of us seek through our time on the yoga mat.

~

Jenni Rawlings loves to weave her natural interest in anatomy and biomechanics into her yoga teaching. She is grateful to so many teachers who inspire her, most notably amazing biomechanist Katy Bowman. You can find out more about Jenni at www.jennirawlings.com.

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8 comments… add one

  • Victoria

    Hi great article, do you have references of where you got your information from? And has it been peer reviewed or checked?

  • Hi Victoria,

    I’m so glad you enjoyed my article! If you look, you can see that I linked to several peer-reviewed studies within the text of my article. Feel free to check them out for further reading. :)

  • John

    My initial reaction was to applaud a yoga article that included references. Unfortunately the bjsportmedicine link doesn’t, the “strengthening doesn’t shorten” link points to a page that claim people typically go through full ROM as part of their daily activity (I wish I did, and I’m relatively active), and the neurological stuff…well…most of us have read Kurz since he first published in 83.

    There’s plenty of hamstring strengthening going on in yoga. If you’ve never been told to strongly contract your hamstrings in a class you’ve been training with the wrong teachers. Stretching and strengthening at the same time is where the rest of us are at. Why do you feel the need for done sort of straw man mainstream that your article will supposedly set right?

    As for “tight” and “short” … Do 200 press ups a day and no shoulder stretches for six months, then try to do wheel. It will feel as though your chest muscles have shortened. Stretch for a while and try wheel again. It will feel as if your muscles are longer.

    The reason the strengthen – shorten language is still in use is that it exactly describes experience. We all know what’s physically/neurologically happening, we just stick to effective language

  • Hi John,

    I hear from your comment that you are frustrated because you are already aware of all of the info I discuss in my piece. You express that “most of us” have read Kurz, “stretching and strengthening at the same time is where most of us are at”, and that “we all know what’s physically/neurologically happening”. I can only assume that the “most of us” to whom you are referring is a more well-studied group of people (I would guess informed fitness professionals or PTs) than the yoga community. Seeing as how my article was published on a *yoga* blog named *YogaDork* (not InformedFitnessProfessionalsDork or PTDork), for which audience do you suppose my article was written? I’m not sure how how well you know the yoga community, but anatomy is hardly covered in yoga teacher trainings, and keeping up on exercise science research is not at all a preoccupation in this field.

    In the yoga world (which consists of millions of practitioners), we are absolutely taught that strengthening muscles physically shortens them, as well as a slew of other outdated claims that are not supported by evidence. My articles are written for this audience.

    Additionally, there CAN be hamstring strengthening going on in yoga, but only if a yoga teacher consciously teaches cues and poses to specifically offer this benefit, which the vast majority do not. Traditional yoga is much more about stretching the hamstrings than strengthening them.

  • John

    You confuse your yoga world with every ones.

    I’ve been going to yoga classes regularly for well over 15 years. There have been stretches of several years where i averaged 8-9 hours a week in class. I’ve covered a huge variety of classes in that time. I easily found (and stuck with) teachers who were fully trained in anatomy (if you do the anatomy portion of a forensic criminology degree you learn a lot) teachers who’s workshops were quite openly coulter’s anatomy condensed and applied, teachers who not only read Kurz but everything else published on the science of stretching. “Yoga is stretching and strengthening at the same time” is a direct quote from one of them.

    Sure, I’ve also met teachers who’s idea of anatomy was announcing which emotions they had decided were “stored” in which parts of the body but they’ve been the minority.

    Those millions of people in the yoga world you’re so helpfully enlightening with the “latest advances” (available since 1983 at least)? A whole bunch of them are ahead of you.

    In the end, as a yin yoga teacher who is also a PhDs student researching back pain said to me after a few beers. “I know all the official explanations of how yin yoga works are bullshit, and I don’t teach them. I also know that I get terrible lower back pain and long, gentle forward bends cure it. I teach that.”

  • John,

    I will have to agree with Jennie. Although it is wonderful that you have been exposed and have had access to well trained yoga instructors, they are NOT the norm. I have no idea how may 200hr graduates there are every year but it is a very large number indeed.
    I choose to spend thousands more dollars to essentially take medical school anatomy and I still have a very small grasp on the subject. Most teachers will not do this as fiscally it is not a great RIO for them. I have never had a client nor a studio ask me what my credentials are in anatomy nor pay me more because I have taken advanced courses.
    The basic 1 hour power flow yoga class with let’s say 30 – 40 people will not understand what you are speaking of if you even mention an anatomical body part. They are simply trying to keep up with the “routine” and hopefully breathe. I am in no way demeaning the intelligence and sensibility of the average yoga student but I believe this is the norm. High school biology was a long time ago for most people and safe to say that is most likely the extent of their knowledge.
    I have traveled the world taking yoga classes for years and this is simply the norm. Most students pick classes based on geographic convenience and or time slots. Very few take the time to research the instructor with the best credentials and experience.
    I choose to work with “masters” in the industry and I can not tell you how many times I speak to young women who have completed 200 hr training, who have no idea who these people are.
    I am not soured nor frustrated with the “state of yoga” I just keep on keeping on and do my part in helping people relieve their pain and find balance in their life and body.

  • Dave

    Thank you Jenni for your thoughtful and informative article. It answered questions I’ve had about the pros and cons of stretching tight muscles since I first started practicing seven years ago.

    I hope that John reads the timely article about what’s wrong with yoga culture in this edition of YD.

    Dave

  • John

    I recently did an online yoga class by kino macgregor in which she said “simultaneously strengthen and release the hamstring” and provided instructions for doing exactly that. Maybe, in your yoga culture, that’s rare and esoteric. In mine it’s the base standard

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