16: Yoga Butt Isn’t About Alignment

June 3rd Workshop: Alignment Doesn’t Prevent Injury — So What Should We Do Instead?

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“Yoga butt” is often blamed on poor alignment in yoga poses. But is the science really that simple?

In this episode of the Enlightened Anatomy Podcast, Matthew Huy explores the research behind proximal hamstring tendinopathy (PHT), why alignment probably doesn’t predict injury as much as social media suggests, and why modern tendon science is more about load, recovery, and capacity than “perfect posture.”

Topics include:
• What PHT actually is
• Why “yoga butt” is a misleading term
• Tendon adaptation and the Cook & Purdam model
• Why pain ≠ tissue damage
• The limits of alignment-based explanations
• Load vs capacity in yoga practice
• Why fear-based cueing can backfire

Reference:
Cook & Purdam (2009) PMID: 18812414

Transcript

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Matthew Huy 0:00

Hello, and welcome to episode 16 of the Enlightened Anatomy Podcast, where we are looking at the topic of, and I apologize for the term, yoga butt. More correctly, proximal hamstring tendinopathy or high hamstring pain. So we're gonna be looking at the science of it, whether alignment helps, and what to do about it. So strap in and enjoy this episode. Cue the intro music.

0:29

Welcome to the Enlightened Anatomy Podcast, where we take a deep dive into the worlds of anatomy, physiology, and science to help you deepen your yoga practice. Now he's your host, Matthew Huy.

Matthew Huy 0:50

So again, sorry about the name, but it's often called yoga butt. It was mentioned in episode eight with Jules Mitchell, and basically, it is a pain that you feel at the base of your bottom, at the top of the hamstring attachments. If you look online, you will see lots of things about how to prevent yoga butt, what causes yoga butt. For example, things like micro bend the knees or tilt the pelvis forward. But then you also see things that say, "No, keep the knees straight, tilt the pelvis backwards." People will say, "Don't round the spine." People say, "Keep the hamstrings engaged" Turn the legs in." "No, turn the legs out." Honestly, it is a minefield out there in the online world of what this thing is, what's causing it, and what to do about it. Well, I'm going to look at this topic and whether alignment actually does help, whether it doesn't help, whether it even plays a role at all. And when you actually look at the science of he- tendinopathy, the picture becomes much murkier and much more nuanced and actually a lot more interesting. So let's define what we're actually talking about. So like I said, it's called yoga butt. But then also that term is used to refer to someone having a pert bottom, which is a, a weird thing, okay, and another reason why we need more technical terms rather than these things like yoga butt, yoga foot, because they're vague terms. The actual term is proximal hamstring tendinopathy. Now let's break that down. Proximal versus distal. So you might recall from your anatomy studies that proximal refers to more towards the center of the body, more towards your torso, and distal means further away. So you have two attachments for your hamstrings, which are at the back of the legs, and they attach below and behind the knee, so onto actually the tibia and fibula, so your shin bones, and then up behind your femur, and they attach up on the sit bones, or the ischial, also pronounced ischial, tuberosities, and by some weird people, sitz bones with a Z. Can we just stop doing that? Stop saying sitz bones. It's weird. That's not any professional opinion. That's just my own opinion, by the way. But anyway, that's where your hamstrings attach. So you have the distal ends below the knee, and you have the proximal ends up by your pelvis. And so a tendinopathy is simply a tendon-related disorder, and your tendons are the things that we often say attach the muscle to the bone. To be honest, it's more of a continuation of the collagen around the whole muscle. So we're always throwing around the term fascia. Well, yes, there is a fascial covering around your muscle which then extends up into the tendon. It gets thicker and stronger around the tendon, and then that tendon wraps around, connects to the bone, and actually becomes then the fascia around the bone. And so a tendinopathy means tendon and pathy, pathology, or, something going wrong, a disorder. And specifically with tendinopathy, all it is is pain and, usually a reduced load tolerance. So you can't do as much with this. It can't bear as much weight. Y- you know, it doesn't function quite as well. Now, just to geek out a little bit on anatomy here, you actually have three muscles of your hamstrings, and that's probably why we make it plural, just like your quadriceps, right? So the three hamstrings are your semimembranosus, semitendinosus, and the biceps femoris. Now- Those three muscles, well, at least the long head of the biceps femoris, they have one common tendon that attaches up onto your sitting bone, your ischial tuberosity, which is actually part of your pelvis. And so when you tilt your pelvis forward, what you are doing is lengthening the hamstrings from the knee up to the sitting bone. And so the the proximal hamstring tendinopathy, or PHT, is a pain, a problem with the tendon just behind the sitting bone, just below the sitting bone. And common symptoms, and remember, this is not medical advice but just describing, something which is supposedly common in the yoga world, but we're gonna get into that. So the common symptoms are a deep pain at the base of the buttock, pain during or after stretching, pain with forward folds, discomfort in lunges or splits, basically any time that hamstrings are involved, and even pain while sitting, morning stiffness, and the other things that you expect from tendon problems. Particularly during acceleration-based movements, so when you start moving quickly, like if you start to sprint. Something that someone might say is, "I feel like I can stretch into it, but it becomes angrier afterwards." And these sorts of tendon problems just feel like a sort of burning sensation. I remember having a Achilles tendinopathy and experiencing this, this painful sensation, which really felt like a burning, sort of angry, irritated sensation. So is this even a problem in yoga? You know, the name yoga butt suggests, of course, that this is something that happens with yoga, just like tennis elbow. You think, "Oh, you've gotta play tennis to do that." Golfer's elbow. Well, I got golfer's elbow from doing too many handstands actually, um, and not properly conditioning my wrists. So that name is not a good one. And what does the research say about whether yoga butt is actually more common amongst yogis? Well, I've read the research. I did this for my dissertation when I was, doing my master's and looking at pain science and yoga, and even language in regards to that. And having read all of the literature on yoga injuries and adverse events, I can tell you hamstring injuries actually did not feature as one of the most common injuries. It tended to be fourth down the list after things like knee injury, shoulder injuries, or back pain. So if, if we look at the epidemiological evidence, which includes primarily surveys, it's not even clear that proximal hamstring tendinopathy affects yogis more than other populations. We can't even say for certain that yoga is more likely to make you have this hamstring tendinopathy. Okay? So let's forget that t- term of yoga butt altogether, and we'll just refer to it as PHT from here on out. So what information we do have about hamstring tendinopathy and yoga is basically correlation and anecdote at the moment. And just to say also, please remember that, as I mentioned in episode one of this podcast, yoga is quite a safe form of physical activity compared to other forms of exercise. And remember, we all need to be doing exercise. It's just essential for good health. Then yoga is probably one of the safer forms that you could be doing. So please don't be put off and think, "Oh, I need to stop doing yoga because of the potential of a shoulder injury or hamstring tendinopathy or anything like that." Now, let's look at what's actually happening in the tendon during hamstring tendinopathy. So this is not usually a simple tear of the tendon. That would be more of an acute event, a trauma, perhaps as a result of an accident or, moving too quickly, you know kicking a ball at high velocity, so this often happens in soccer, for example. And hamstring tendinopathy is not well explained by the idea that the tendon was simply overstretched once. Rather, it's a slowly progressing sort of longer term thing. There are two researchers, Cook and Purdam, who have done a lot of research on tendinopathies, and they describe tendinopathies on a continuum. So rather than thinking of just healthy tendon versus damaged tendon, they talk about how, tendons adapt, and they can change with appropriate load. So a tendon is still a living tissue. It is full of cells which are metabolizing ATP. It is creating, laying down new layers of collagen, and it is basically rebuilding itself or remodeling. So don't think of it as a static one and done thing. You know? It's not like you're born with it and then it's just slowly degrading over time. No. It is constantly adapting actually to the demands placed on it, just like all other tissues in the body pretty much. And so with appropriate loading and rehabilitation, symptoms and tendon health can improve. So this model is a dynamic one. It's not a one-way degeneration story, and so the modern understanding of tendinopathy is much more about how tendons respond to load over time. But if loading, you know, so the tension on the tendon, and the word tendon actually comes from Latin tendere, to, to stretch or to tension, and that is exactly what a tendon does. It experiences tension. But if that tensile load exceeds the tendon's current capacity, especially, especially repeatedly or rapidly, that's when we can have symptoms emerge. That's when we can get this irritated tendon. And just, you know, there's an important distinction that pain does not necessarily mean tissue damage in a simple one-to-one structural sense. So not more damage equals more pain. Okay, so we've looked at the tendon, what happens to it, how it's a living tissue, but what actually causes PHT? And according to, or the, the, those online influencers I mentioned earlier, it will be having your feet turned in or having your feet turned out, or, you know, these sorts of alignment-based things. But actually, uh, the research points to something else. Before I go into what we believe, what scientists believe are the causes of tendinopathy, let me first talk about causality. What causes what? And this is at the center of all science. This is at the center of all hypotheses, or at, or at least most hypotheses in science. We're, we're trying to understand what causes what in the world and why. And this is important to think about because yoga culture often treats biomechanical theories as though they're proven with the certainty of smoking causing lung cancer, and let's look at how, how that plays out actually. So if we look at smoking and lung cancer, there is actually massive epidemiological associations between those two, and there's definitely a dose-response relationship. So if you smoke more, you're more likely to get lung cancer later in life. And it is a time-based sequence, so it, you know, if you do this one thing first, smoke, you are more likely to have this other thing happen later, lung cancer. It is consistent across populations, across sexes, and also people's risk reduces after they quit. So this is all very well studied in, in the scientific literature, you know? And that's why we can say smoking and lung cancer are considered a very strong causal relationship. Although, having said that you know, though smoking does increase your chance of getting lung cancer by twenty to thirty times, depending on, you know, which studies you're looking at, not everyone who smokes gets lung cancer, and in fact, it's something like only one in five or two in five. So we can't even say with certainty that if you smoke, you're going to get this thing. Do you see how complex causality actually becomes when you start to really dig deep into it? Now, an even clearer example actually is HIV and AIDS. So you have to get the HIV virus in order to get AIDS, So if you reduce people's chances of getting HIV, you will reduce AIDS. That is a, a clear cause and effect. Now, let's contrast that with PHT, proximal hamstring tendinopathy. The evidence is nowhere near that clean. Here's what we do have in terms of it. Associations, mechanical theories, ideas, clinical observations, plausible mechanisms, and load-based models. It's not that same evidence that we have for smoking cancer or HIV and AIDS. What we do not have is one universally reproducible cause, you know, like smoking. We do not have one predictive certainty. We do not have one specific movement pattern that reliably causes this injury. We do not have large sample sizes of this relationship. And we just don't have that simple linear relationship. And that distinction matters enormously because saying this pelvic position increases tendon compression in a biomechanical model is not the same thing as saying this alignment causes injury, as you so often see online. So here's one great example. One student, one yoga practitioner can probably do deep forward folds for twenty years with no symptoms whatsoever. You know, I've been doing yoga for twenty years. I've never had a hamstring problem. Another might develop pain during a period of increased stress, reduced recovery, lack of sleep, incru- increased class frequency, reduced strength training, and perhaps also adding long yin holds. So human bodies are not the same engineering systems. We are not machines. Here's what's missing from the evidence currently. There's no strong evidence showing that one specific spinal or pelvic alignment reliably predicts proximal hamstring tendinopathy. That doesn't mean alignment changes nothing. Your position in a yoga pose can certainly affect how weight-bearing, load-sharing is happening to some degree. But influencing load is not the same thing as directly determining injury. S- so basically, alignment may slightly redistribute forces, but tendons care far more about total loading exposure over time. Okay, having said all that, here's what researchers currently know about causes of PHT. So it affects various populations, but particularly athletes like runners But also, if you are a middle-aged adult, you're more likely to get it, so if you're between 30 and 50. For perimeno- perimenopausal or post-menopausal women, you're more likely to potentially get this because estrogen can play a role in collagen synthesis in the tendon. Sedentary individuals for sitting for too long or if not sitting, then just the act of not being physically active can also contribute to someone's PHT. Other believed causes of PHT are what are called training and overload errors, so for example, suddenly increasing your training volume or intensity can contribute to PHT. Specific running styles like uphill running or speed work or interval training might also contribute to PHT. And excessive compression. So activities that combine high tension with hip flexion, so flexing the hip past ninety degrees, might also cause the tendon to compress against the sit bone because your tendon attaches to the sit bone at the back, but then as your pelvis rolls forward, that tendon comes into a compressed state, so that might also play a role in proximal hamstring tendinopathy. Maybe even sitting for long periods of time, though we don't know if it's that compression or that reduced activity as the cause there. There could also be internal factors involved, so like weakness or deconditioning of your hamstrings, of your tendons and your hamstrings, both. And like I said earlier, um, tendon structure changes with your age, and there's even some research showing that people with higher tendon metabolism, so tendons which change more quickly, adapt more quickly, a- actually might be more susceptible to tendinopathy. And lastly, things like diabetes, high cholesterol, and poor nutrition can reduce the tendon's capacity to repair. And of course, genetics affect everything. So some people are just predisposed to get a hamstring tendinopathy than other people. So you see how lots of different factors go into our current understanding of PHT, and so that's why we say its cause is multifactorial. So lots of factors go into it. And here's why alignment explanations can actually become problematic. Alignment explanations, they work really nicely, don't they? They create this illusion of precision. If you just turn your feet in a little bit more, this will stop all of your hamstring tendinopathy. If you can just perfect that pelvic tilt, if you can find a neutral spine when you're doing your forward folds. But biology is a lot messier than that. And actually, if you tell people that they always have to go into this certain alignment whenever they come into a forward fold or do a certain yoga pose, it can create fear. It can create avoidance of certain movements. It can even create this idea of catastrophization or thinking the worst will happen if you do go into this position. And actually, we have many ways of doing the same thing with our bodies. We have many degrees of freedom, as it's called. If you think about a door hinge, it can only move in one way, or a zipper on your coat. It can only function in one way, and if y-you don't get the alignment just right, it doesn't work. Your body is not like that. You can have many different alignments. Look at a tennis player's knee when they are running around the court, and if you can get, like, a photograph of it, you can see their knee is gonna go in so many different directions. And that is why we are so good at tennis versus, say, a robot trying to do the same thing. So a better model for thinking about hamstring tendinopathy is to focus on capacity rather than load. Loading is thinking about alignment and which structures are absorbing how much force and that sort of thing, which certainly does affect things in the body. But what we want to do is build a greater capacity, and capacity includes things like strength, recovery, sleep, even good nutrition, adaptation to exercise, so getting stronger through stress, general overall health, and of course, your previous loading history and previous injuries. Injury risk in general is probably less about whether the spine was rounded five degrees or the pelvis was tilted anteriorly versus posteriorly slightly, whether the knees were bent a few degrees or not, and much more about whether the tissue was prepared for the demands being placed on it. All right, my friends, if this has started to shift how you think about alignment and injury, and you're starting to see that it's a bit more complex than just finding the right position, then there's a whole next layer to this, and especially when it comes to what you actually do as a teacher in real time. And that's why I've created a workshop called Alignment Doesn't Prevent Injury, So What Should We Do Instead? So check it out in the show notes. And until next time, thanks so much for tuning in, and I'll see you around!

22:12

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