Did you know that for all of the attention we yogis place on the topic of stretching, there are many (many!) unsupported beliefs about this simple activity that permeate the yoga world? I've covered several misconceptions about stretching before and will continue to do so, such as:
-stretching & strengthening are opposites ---> myth!
-stretching a muscle "releases" it ---> myth!
-stretching our connective tissue can lengthen it out so it becomes lax ---> myth!
But today I'd like to focus on one myth in particular that I don't believe I've addressed recently. This myth is the common claim that stretching weakens our muscles.
We often hear this claim in the form of warnings like "stop stretching your hamstrings because it weakens them". Or "sitting weakens your glutes" (because they're in a stretched position when you're sitting in a chair).
This claim is also at the root of beliefs about posture, such as rounded-forward shoulders (often referred to as "upper crossed syndrome"), in which we're told that the rhomboids (mid-back muscles) are "long & weak" because they're in a stretched position.
Now if you know my work at all, you know I'm a huge proponent of yogis incorporating strength into their yoga practice. And a large portion of the yoga world seems to be moving in this direction as well, which makes me very happy!
But as with all perspective shifts, the pendulum tends to swing toward extremes before it settles somewhere in the more grounded, evidence-based middle. Along with the widespread enthusiasm for strengthening, there is a large amount of fearmongering about passive stretching taking place in the yoga world today.
Although strengthening is indeed awesome for us, this doesn't mean that stretching is bad for us. And if you refer back to the common myths I listed above, you'll note that stretching & strengthening aren't opposites anyway, so there's no need for us to pit them against each other. We can be pro-strengthening without being anti-stretching!
Which brings me back to today's stretching myth. One common claim we hear that gives the mistaken impression that stretching is bad for us is the myth that stretching weakens our muscles. I'd like to bust this myth once and for all, using the handy tool of muscle physiology.
What is the one way in which muscles become stronger? When they contract against a high enough resistance that they are stimulated to adapt to increase the amount of force they can generate. Our muscles strengthen when they do strong work: lowering slowly into chaturanga, moving heavy weights around, etc.
Knowing this, what is therefore the one way in which muscles become weaker? The one and only way that muscles grow weaker is when they don't do strengthening work. That's it! If we don't expose our muscles to progressive loads, they will weaken.
Whether we stretch or not has nothing to do with muscles strengthening or weakening. Strengthening has to do with force production, while stretching has to do with tissue extensibility. These are two separate qualities.
The claim that stretching muscles weakens them is completely unsupported by science. Which means that we now have one less reason to fearmonger about stretching! :)
For a deeper dive into what we do (and don't) know about stretching, consider my online mini-workshop How Stretching Affects the Tissues of the Body. As many yogis who have taken this workshop have expressed, this should be required info for ALL yoga teachers!
My mentor Jules Mitchell's brand new book Yoga Biomechanics: Stretching Redefined is also an excellent, thorough resource on all things stretching. I highly recommend it!