9: Holger Cramer on Yoga Injuries and Yoga for Depression

Matt welcomes Dr. Holger Cramer, a leading researcher in complementary and integrative medicine, to discuss the scientific evidence behind yoga's impact on health. They explore Dr. Cramer's extensive research on yoga's benefits for cancer patients, low back pain, asthma, and its role in mental health, particularly depression. The conversation delves into the safeness of yoga, comparing injury rates with other forms of exercise, and the complexities of studying yoga scientifically. Dr. Cramer emphasizes the importance of systematic reviews and meta-analyses in consolidating available evidence while addressing the challenges inherent in yoga research. The episode concludes with a peek into ongoing studies on post-COVID fatigue and the potential future direction of yoga research.

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Transcript

Matt Huy: 0:00

Today's guest is someone you will never have heard of, but you maybe should have. It is Dr. Holger Cramer, who has conducted lots of research on whether yoga is beneficial for people with cancer, whether yoga is beneficial for people with low back pain, whether yoga is effective as a treatment for asthma. And he's also done lots of research into how safe yoga is in terms of injury risk, adverse events, in comparison to other forms of exercise. Without this researcher, we would not have the evidence based information that we have today to say that: Yoga is beneficial for people with depression. Yoga is beneficial for people with asthma, although it might not cure their asthma. And I am completely honored to have had the opportunity to interview him. It's a brilliant interview. At the same time, just to let you know, there are some quite technical terms that will be used in this episode. I highly encourage you to stick around to the end because it gets really juicy. It's great throughout, of course, but it's particularly juicy at the end when Dr. Cramer starts talking about the biopsychosocial model of pain and how pain, injury, are nuanced and how beautiful science actually can be. So, enjoy this episode. Thanks for tuning in.

Saz: 1:53

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, here's your host, Matthew Huy.

Matt Huy: 2:10

Hello, and welcome to the Enlightened Anatomy podcast. And I'm joined today by Professor Holger Cramer PhD, who is a leading researcher in the field of complementary and integrative medicine with a particular focus on yoga and its therapeutic applications. As full professor at the University of Tübingen, which I'm sure I'm mispronouncing, and scientific director of the Robert Bosch Center for Integrative Medicine and Health at Bosch Health Campus in Stuttgart, Germany, Dr. Cramer's work bridges the gap between ancient practices and modern science. So I am very honored to have you join us here, Dr. Cramer.

Dr. Holger Cramer: 2:55

Thanks a lot for having me and sorry for giving a hard time with German city names.

Matt Huy: 3:01

How was it?

Dr. Holger Cramer: 3:02

It was perfect. So your Tübingen was perfect.

Matt Huy: 3:06

Okay. Um, I'm actually German by descent. My grandparents, that was their first language. And my father's first language until he emigrated to the U. S. when he was six, actually. Um, so let me start by telling everyone how I first learned about you. So I did my master's in exercise science. And my dissertation was all about yoga teacher's language and how it has the potential to heal as well as to harm. And in one of my previous podcast episodes, I interviewed Jules Mitchell, who was talking about how yoga is really safe. She was talking about how it's low load, low intensity. Um, you know, you're not throwing weights across the room. You're not even lifting weights overhead. Um, and so this idea that yoga is dangerous is quite a preposterous one. So. I ran with that idea. And of course, my advisor said, well, you need to have evidence. So I had to look up the evidence. So is yoga safe? And then that took me down the rabbit hole of yoga injuries, yoga adverse events. And this name Cramer kept popping up, of course. So, um, one thing that I, that I read, of course, early on was this article by William J. Broad, which appeared in the New York Times magazine, entitled"How Yoga Can Wreck Your Body." And it went into anecdotes, really, of certain people who had been doing yoga, and then they had a stroke, for example, or other such cases. And interviews with, non medical people, non scientists saying,"Oh, yoga is really dangerous. It's not suitable for the general population." So I quoted this in my dissertation. And then I also quoted the actual research that came out of that. You know, your studies from 2013, 2015, 2019, which did look at the evidence on yoga related injuries, and let's start here. What did those studies find?

Dr. Holger Cramer: 5:09

Yeah, sure. So first of all, I have to say, it's really important that Broad ticked into this area. So before that, most people are really just thinking yoga is very soft and very gentle and you can't get injured by doing yoga. And of course it's wrong. So yoga can be quite effective. And of course it can be side effects. It can be adverse events. And it's important to look at it. As you said, best from a scientific angle. And there are some anecdotal reports, like case reports, for example, really showing that there can be serious adverse events. There can be like stroke, like fractures, neuropathy, so damages to the nerve. So there are some cases where this happens. When we overall look at the evidence from more scientific approaches like representative surveys and clinical trials, then we see that there are injuries, but that most of them are very minor and transient. So, for example, like minor sprains and strains, um, like you get sore muscles after practicing yoga, you might stumble over the edge of the mat and fall and injure yourself slightly, but it's not really often that you injure yourself seriously by doing yoga. What we found in our surveys mainly is that about 20 percent of yoga practitioners, so one in five, has ever injured by doing yoga. And this is a bit less than we see in other forms of physical activity. So as you said, yoga is not a high intense sports or exercise performance. It's really a gentle way to move. And we see that we have less injuries than with other forms of exercise or other forms of movement, but we can see injuries. And of course, you have a higher risk of getting injuries, for example, when you have a chronic condition. So there are some risk groups that should be a bit more careful and perhaps speak to the yoga teacher or yoga therapist about their condition. But then compared to other forms of movement, it's relatively safe.

Matt Huy: 7:23

Right. Yes. And one of the ways to measure, you know, how safe something is, is to look at its injury rate per 1000 hours practiced, correct?

Dr. Holger Cramer: 7:35

Yeah, absolutely. Yeah. And

Matt Huy: 7:38

do you remember what those were for yoga?

Dr. Holger Cramer: 7:40

Yes, I, I remember what it, what it were, and it's, uh, 0. 7 injuries per 1000 hours of yoga practice. So you have one injury, about every 1,300, 1,400 hours. And this is still a bit abstract, but if you look at other forms of exercise like cardio training, like running, for example, you end up with about 2. 5 injuries per thousand hours of cardio or running. It's much higher with soccer or tennis or skiing, for example, but even with those rather low intensity exercises. It's up to four times as much injuries as with yoga. But it's important to see that it's not normally being compared in a single survey. So we have different surveys that we can compare and we see that there the injury rate seems to be much lower with yoga. But of course they're not completely comparable so they used other sampling methodology, other forms to query exercise or yoga or sports, and perhaps it would done in different countries. So they're not directly comparable, but based on that, we can say that the injury rate per thousand hours of practice is relatively low.

Matt Huy: 8:57

And maybe it wasn't your study, but another one, which also compared injury rates. And they found Ashtanga was closer to 1.5 injuries or adverse events per 1000 hours. But if we put that into context, if you were to do an hour long yoga class, let's say twice a week, it would take you about 7 years before you get injured based on that number.

Dr. Holger Cramer: 9:21

Yeah, true. So there was a Finnish study on Ashtanga Yoga, I'm not sure it's the one you're referring to, but those were really high intense Ashtanga Yogis. So they were really practicing a really high level. And of course you have higher injury rates also with power yoga, for example. So you can have higher injury rates, but it's still relatively low. And as you said, you can expect to injure yourself after a long life of practicing yoga once or twice, and then it's relatively low, uh, low impact injuries.

Matt Huy: 9:55

Yeah. Like not very severe, like you said, sprains and strains and that sort of thing. Yeah. Yeah.

Dr. Holger Cramer: 9:59

Yeah. You can't be sure that you don't hurt yourself by doing yoga.

Matt Huy: 11:13

Yeah. And the reality is yoga is physical, just like all physical activity, and all physical activity carries the risk of injury.

Dr. Holger Cramer: 11:21

Absolutely. And practicing no form of physical activity also carries the risk of side effects. So it's, whatever you do, being a human being, you can't be totally safe. And, um, As with other form of activities, you can, you risk being injured by doing yoga. And I think this is important because some people still think it's absolutely impossible to harm yourself by doing yoga. So there is a relatively low risk, but it is there.

Matt Huy: 11:52

And I remember being upset when I first read this Broad article about how yoga is dangerous. And it really rubbed me the wrong way. And I thought, oh, this is using, this is not using critical thinking. It's not using good evidence. But then in the end, I think it's done the yoga world a benefit. so while I was doing my research for my master's, your name kept cropping up. And I thought, I'm going to thank this guy. So I sent you an email and I said, You know, just thank you for your work. It's, it's, it's been so important in the yoga community because now we can point to some scientific evidence and say, look, yes, if we look at injury rates, based on yoga compared to other forms of physical activity or exercise, it is relatively safe. But we, we didn't have that really before you. We didn't have these systematic reviews and others have come out since then, or, or other surveys, I should say. But, um, it is really thanks to you that we've had that systematic review. And as I asked you in the email, you know, did that Broad article inspire you to, to look into this research? And what was your answer?

Dr. Holger Cramer: 12:56

Yeah, it definitely did. So, the Broad article and just as a book was not so popular in Germany. So we, we had some, um, reminiscence to that also in German newspapers, but the upset was not as strong as it was in North America. But of course I work a lot with North American colleagues and I also looked up at the, its impact in the internet. And I saw that many people. really insecure, whether they should continue practicing yoga or whether they should switch to pilates or do something completely different. Um, and so it really was important to sharpen our look and to bring us to look into, safety. And really when I saw it, I thought, okay, there seems to be some upset and some, some fears that yoga might be dangerous. And I think I would not have done the systematic reviews on the safety and also, um, a survey we have done on safety of yoga. if they would not have been in this book. So I think it's, it's important. Of course, it's a popular book. It's not a scientific book, but it's sometimes really important. Some, someone from the outside saying, okay, we don't have strong evidence on that yet. Perhaps you take a look on whether there is strong evidence.

Matt Huy: 14:10

Yeah. So in that way, it did, it did inspire. Yeah. So I mentioned the article, the entitled, you know, How Yoga Can Work Your Body. And then you just mentioned the book, which ironically is called, I think, The Science of Yoga. Even though it's not at all scientific, it should not be taken as science. It is a compilation of anecdotes. And if, if we can even say case studies, even though they aren't proper case studies based on the scientific method. But both of those. And as you say, sometimes it can take that. poking to say we do need some evidence.

Dr. Holger Cramer: 14:44

Absolutely. And those popular books, of course, are important to also alert the public to some things. And if you just list the studies, it can get boring, so to really write up something that is scientifically correct and in depth and still catches the public interest. Of course, this is a gold standard, but still I think the article and the book were quite important to, to bring up the discussion on safety and effectiveness. And we have quite good evidence there on both sides, both for safety and for effectiveness now.

Matt Huy: 15:19

Yes. Okay. So for effectiveness, could you talk to us about that?

Dr. Holger Cramer: 15:23

Sure, how much time do we have?

Matt Huy: 15:25

Okay, let's start with, 2013, um, yeah, a 2013 systematic review you conducted on the effectiveness of yoga for depression, which I, we quote in our book, we quote in our Physiology of Yoga eight week course.

Dr. Holger Cramer: 15:44

Um, actually the, the one you just quoted is getting a bit outdated and we just updated it. So, um, uh, the paper has just been accepted. It may be that it's not yet listed. It's just been accepted a few weeks ago where we updated based on the now available evidence. Um, and what do we actually see both in the first article and in the updated one is that yoga can be quite effective for depression actually. So, We now even with the newer, newer data, we see that yoga can not only be effective for everyday depression. So when someone says, I feel depressed today. They don't normally mean they have a major depression or a depressive disorder, but they mean that they have lowered mood. And we already knew from the 2013 article that yoga can be helpful here, so that we can improve and lift our mood. Stronger than, for example, with relaxation techniques. Now with the updated one, we see that yoga can also be quite effective for major depression, so that yoga can help with manifest mood disorders. And normally this is done in addition to a standard treatment, so to either psychopharmaceutical or psychotherapeutic approaches. And yoga can definitely be recommended to be added to psychotherapy, for example. Or if you, for example, don't get a treatment in psychotherapy because there are no therapists, because you can't afford it. then yoga could also be a substitute for some time until you get proper psychotherapeutic training. And we definitely see a relatively strong effect on depressive symptoms.

Matt Huy: 17:28

Amazing. That's, that's powerful research because previous to this research, a lot of yoga textbooks will just make these claims with no evidence behind them. And they'll often point to individual poses. Mm hmm. For example, Iyengar's Light on Yoga will say things like, Paschimottasana, seated forward fold, is good for relieving depression. It's like, well, okay, where does that come from? What evidence do you have to back that up? And it's more likely that it's yoga's overall effect that has that benefit, doesn't it?

Dr. Holger Cramer: 18:08

I totally agree. So I'm often asked on, on which poses based on our research, I would, I would recommend for people with depression or with depressed mood, and I have to say there is very little research into specific poses. So there are very few studies, for example, looking at immediate effects. For example, if you. bend backwards and open your chest and get a more upright position. There are some studies showing that you can elevate your mood and get a little bit less depressed, but we don't know on whether this translates in longterm effects for depressed mood. And you really see with our studies that yoga, as they say, multi modal intervention, so build up of different postures, of breathing, of meditation, perhaps even looking differently at your lifestyle, eating differently, being more careful with your body. All this together seems to have an effect. And there is good evidence also, for example, from neuroscience that breathing and meditation may be important for this effect and not just specific postures. So, for example, that you can influence how your brain works by meditating, by using pranayama, breathing exercises from yoga, but also by postures. And I, I would not be able to pick out a single or even a few postures that help with depression, but I can say that overall yoga as a concept is effective.

Matt Huy: 19:37

Yeah, it's hard to tease out what exactly is the effective ingredient, if you will, in the yoga practice. Is it, is it the poses? Or is it connecting to your body? Or is it being guided by someone? Or is it the self efficacy that comes out of taking some action on your own and saying, I'm going to go look after my body and do a yoga class? Or is it being in a community with other people? Or is it going into a beautiful studio? So it's, it's, it's, it's all of these different things. And I would guess doing yoga alone in your house, it would be different to going to yoga in a community setting, you know, so both might be valuable both, you know, I just imagine it would be different. And it's, it can be difficult to tease out which one is the most effective.

Dr. Holger Cramer: 20:25

Yeah, so it's, it's not normally compared in studies, and so we don't know, so we would have to design a study to see whether doing yoga on your own or yoga in the class makes a difference. What we see now, not so much with depression, but for example with elderly people, also with heart disease, is that, um, tele yoga, so doing yoga online versus in the class has been more and more compared. So of course, it's during the pandemic when people did not leave their house or many yoga studios were shut down. They started with online yoga and we can see that it's, it's, about as effective as doing yoga in a yoga studio. But of course you're still doing it in the group and when you have a good yoga teacher, a good yoga therapist, they can build up something like a group spirit even when doing it online. And this seems to be quite, quite effective. Um, but overall we can't really compare what, what we see is when we might step back to, to injuries is that if you start doing yoga on your own and you do not learn it with a yoga teacher or yoga therapist that you increase your risk of being injured. So if you don't learn it, the good way from the beginning, someone correcting you when you do it wrong, then you increase your risk of injury. So I would always recommend at least for the start, it's good to start in a class or in an online group or to have someone to supervise you.

Matt Huy: 21:53

Yeah, that totally makes sense. We also teach online, my partner and I, so we have online classes, which we started during the epidemic, and they've just carried on. And we definitely foster a sense of community within that. So it's not the same as being in person, but there's definitely this community of five, six people who are coming to class regularly, and they get to know each other. I can imagine those benefits would be similar to the community benefit that you would get from being in a group class. Yeah. And then you also mentioned, what was the other point you mentioned? Oh, I don't remember. But anyway, going back to injuries. Okay. You mentioned that a few of the studies came from surveys. Okay. And surveys, self reported surveys have problems. What are some of those problems with self reported surveys in relation to injuries?

Dr. Holger Cramer: 22:46

A problem is that most surveys, rely on, reporting something that has happened in the past. So you can do two different forms of more epidemiological studies. You can do a cross sectional study or you can do a prospective study. And if you do a prospective, then you say, From now on, for say one year, please collect all injuries you had during your yoga, yoga classes or while practicing yoga at home, but almost no survey does it because it's really cost intensive. You lose a lot of people while doing it. It's very difficult to do. So most surveys actually ask, in the past 12 months, have you injured yourself while doing yoga? And of course, You have to recall that and some people might forget minor injuries and some service even go further and they say, have you ever injured yourself by doing yoga? And when you're very experienced and you started doing yoga as a kid and now you did it for 30, 40 years, you will not remember all injuries you had. Um, and so you will not get an unbiased result by asking, have you ever been injured in the past? Another problem is that it's, It's often hard to get a representative sample. So of course you want to have a sample that is really representative for all yoga practitioners, or perhaps even for the complete population. So this would be ideal if you would say, 15 percent of the population practice yoga, and you have a nationally representative survey, and you could compare those 15 percent to the 85 percent who do not practice yoga, like you normally don't have it. So normally you have something we call a convenience sample. So for example, Um, you just do an online survey and you send it to yoga teachers, you know, and they spread it by a snowball system and you get a few hundred results and it's great. You get a nice overview, but you don't know who responded and who did not. And when you say it's on yoga injuries, you might lose people who have never injured themselves because they say, I can speak about, can't speak about that because I never injured myself. And so there are different things. that makes you a bit less confident in how reliable and how generalizable, uh, general, sorry, generalizable those data are. They are still good and they are still usable, but they are not perfect. And you normally do not get a perfect data quality when doing yoga surveys because it costs a lot of money to do it very, very properly.

Matt Huy: 25:24

Another problem is that people tend to be biased. You know, they can't, I mean, we are all biased. It's not that we tend to be. We are all biased. And we can't remove our biases. And so, if we believe that yoga caused our injury, we will write that down, whereas it could just be the case that that happened to be the culminating event, right, after a few days of sleepless nights, and maybe some stress at work, and maybe sort of pre injuring yourself in an event that happened earlier that day, and then just you start to feel it during yoga. Is that not right?

Dr. Holger Cramer: 25:58

Absolutely. So one, I would really say contraindication against some form of yoga is glaucoma, for example. So increased pressure in your eye, and this is inheritable and, um, the pressure increases because the fluid in the eye can't flow out of the eyeball and the pressure increases and it can up with, with getting blind. Um, and it has been shown experimentally. that when you do, um, upside down postures like shoulder stand or, or headstand, for example, you increase your interorbital pressure. So you increase the pressure in your eye. And there also are, um, case reports of long term yoga practitioners who did a lot of inversions like headstand, like shoulder stand. who had a progressing glaucoma. And it's quite likely that it's associated with each other because we see a lot of such cases, so that when you have glaucoma or increased intraorbital pressure, you should perhaps not practice inversions. can practice almost all other forms of yoga, but perhaps do not practice headstand or shoulder stand. But you of course don't know. It might be just a strange coincidence that this happens that people with, um, people who practice a lot of inversions have a higher risk of glaucoma. And the same is true for other things. So just because, as you said, Things coincide, we don't know whether it's causal. And we also don't know when we follow, when we do it prospectively, but we have, um, a slightly higher chance that there is a causal relationship. And the only way we can really know it is by, by doing an experimental study, like a clinical randomized controlled trial. Then we can more or less know, know for sure.

Matt Huy: 27:49

Right. Yeah, coming to causation is at the essence of experimental science, right? And yet it's actually a lot harder to arrive at than we think. So it can be fairly easy for drugs because you can take a placebo. especially if you can control other variables, such as having people stay in a hospital, you control the food that they eat and you control the stress that they encounter and that sort of stuff. And you just give them one of two. pills, a placebo, or this other thing. And that can be pretty well controlled. But yoga, it's harder to control for it, simply because you cannot blind people to the fact that they are doing yoga. And so then they already have the expectation that they're going to feel better. And so is it their expectation, or is it the actual yoga? And are there other problems that we encounter with yoga in terms of methodologies and studying it in a scientific way?

Dr. Holger Cramer: 28:47

So it's, definitely possible to do randomized controlled trials and it has done, has been done a hundred of times. Um, so doing a randomized trial essentially just mean that you don't ask people what they want to do. So when you compare yoga to doing nothing or yoga to exercise, you don't ask would you prefer to do yoga or to do exercise or to stay on the sofa, but you do it by using a computer randomization, where people can't choose where they end up. And this is as easy as it is with a drug. But as you said, there are other things that are considered gold standard in clinical research. And this, for example, is blinding. Um, and when you do a standard yoga study, of course, you can't blind people. Um, there has been some efforts to, to do that. For example, there's an Indian yoga study on pranayama for asthma, and they invented something they called the Pink City Lung Exerciser. Um, and it mimics pranayama, so it changes the, um, your, your inspiration and expiration rate to, I think it prolongs expiration, it might be the other way around, to very basically mimic pranayama. And then they invented a placebo lung exerciser that does nothing. It just looks like the other one, but it does not change expiration or inspiration. And they say, okay, now we have pranayama and placebo pranayama. But when you're practicing yoga, you can ask yourself whether this actually is pranayama. I would say not really, and it definitely is not yoga. So it's a very tiny component taken out of yoga and they invented a placebo for this very tiny component of yoga. There's no intention in it. There is no mindfulness in it. There is nothing beside changing breathing frequency. And this is where you end up when you try to find a placebo for yoga. If you want to really study yoga as a whole. I doubt that there will ever be a placebo, and I also wonder whether it makes sense to have a placebo, because as we spoke about it, Yoga, of course, is, it consists of asanas, it consists of pranayama, it consists of meditation, but it also consists of practicing in a group. It consists of practicing with a teacher or therapist, it consists of getting in a quiet space where I'm with myself and with my group, and we would need to control for all this to really come to the physiological effects of, say, a yoga posture. And I'm not sure if this would still be yoga if we take all those unspecific things away and just come up with something that happens in the body. So I think the idea of really taking the pharmaceutical approach as a 100 percent blueprint for yoga research, might not be effective. But still, of course, we're judged against the way people think research should be. And, um, so people just see, okay, this is not blinded, this is not placebo controlled. Can we trust this evidence? And this is definitely a methodological dilemma we have with yoga, but also with exercise, with physiotherapy, with psychotherapy, with everything that is not a drug.

Matt Huy: 32:17

Yes. It's hard to take it out of those contextual factors. Yes. And those contextual factors matter just as much as, as the original thing. Yeah, that's a good point. But on top of that, there's also a lot of bad studies out there, aren't there? A lot of studies with poor reporting or poor methodologies.

Dr. Holger Cramer: 32:36

Absolutely. So what we see quite often, and we have seen this much more in the past, but we still see it is that yoga research is not really powered by big companies like it is in drug research. And it's, this is not a critique. It's just how it is that most, uh, drug pharmaceutical research is financed by pharmaceutical companies. And most yoga research, at least in the past, has been funded by small, enthusiastic research groups all over the world. So the typical yoga study in the say, 70s to early 2000s was that there was a yoga practitioner who was also a cardiologist, who was working in cardiology. and heard that yoga might be helpful with hypertension. And so they thought, okay, I'm a yoga practitioner. I'm a cardiologist. I will set up a yoga study for hypertension. And of course, they did not have much money. They did not have good research trainings. They did not have A strong institution that supported them. And so they did the best they could to set up a yoga study. And of course, the best they could was not the best possible. And so we see a lot of yoga studies that was done as good as possible and with the best intentions, but that were not perfect methodology wise. And we still see this, but we now also see more and more high quality yoga studies because there now is some funding, for example, in the U. S. by the National Center for Complementary and Integrative Health. It's a division by the NIH, and they really have a few millions of dollars per year to conduct complementary medicine research, and yoga definitely is on the list. So they have given a few million dollars also for yoga research. And there we see really high quality yoga studies now, but we still also see very low quality studies that are meant good, but perhaps do more harm than they really help.

Matt Huy: 34:39

How are they doing more harm than they really help?

Dr. Holger Cramer: 34:42

Um, because, um, where we end up sometimes is that if we compile studies and we do a meta analysis, for example, we often end up with a few high quality studies and a lot of noise, I would say, studies where we don't know whether we can trust the results. And so we, we often end up with an overall body of evidence that has a relatively low quality. And we then need to carve out the really high quality studies and so called sensitivity analysis. So we remove all those that are biased or might be biased or, as you said, report badly and we don't know how the quality is. And we only find the true evidence in the, in the subgroup analysis or in the sensitivity analysis. And that's totally fine. But of course, it would be better if you would just have high quality studies and it would look more convincing when we would find it in the overall analysis. But as I said, it's the same problem with other forms of behavioral interventions.

Matt Huy: 35:50

Yeah. And for listeners who aren't familiar with those terms that you just shared. So, a systematic review it's considered the highest level of evidence on the hierarchy of evidence. It looks at all the studies that have come before it. From, you know, randomized controlled trials to case reports, all the way down to expert opinion, potentially. They'll look through the scientific databases, choose a few keywords, such as yoga, injury, adverse event, that sort of thing. And then they'll compile the information. using a rigorous systematic method, for example, like the, the Prisma guidelines, right? So it has to be done in a systematic way, a transparent way, so other people can, they could replicate this if they followed the same keywords and did the same research, they would come to the same conclusion. So that's a systematic review, which you've done quite a few of. And then you also mentioned a meta analysis, which is when you, as the researcher, take data from the previous studies. So they're actual numbers, um, and then do your own computations on those numbers to, to then arrive at a conclusion that, yes, yoga did lower blood pressure or it did not lower blood pressure. And, and that meta analysis, uh, will, will be a little bit more rigorous, if I'm not mistaken, in the computations.

Dr. Holger Cramer: 37:07

Absolutely, a perfect summary. The whole idea is that, um, single studies can be mistaken, but it's very unusual that a larger body of studies is mistaken. So we have a lot of, um, conventions in science. So we often think it's all set in stone and it's all natural laws, but many things are just negotiated. And so for single studies, we accept that 5 percent of our findings are wrong. If it's just a risk of 5 percent of being wrong we say, that's acceptable. But of course there is this risk of single studies being wrong. And so if we have one positive study, uh, we, we can't really say, okay, now we know the truth, but if we combine say 15 or 20 or 100 studies, then we can be a bit more confident that our findings really reflect reality. And this is, as you said, what we do in a systematic review. And in the meta analysis, we also do the same, and it can still be wrong, but we increase the number of studies, we increase the number of participants, and we hope to reach a higher level of confidence about the results. findings than with a single study. So a single study is fine and that's a first hint, but it's never, it should never be the end. And we say, now we know it, but we need more studies. And based on that, meta analysis.

Matt Huy: 38:36

Science is iterative in that it iterates what's gone on before it, right? And then it's also self correcting, as you said. So if there is one study, which is an outlier, it will consider that against all of the other studies. And for that reason, I think science is beautiful. You know, I really think the, the, the methodology and, and the fact that it corrects itself. As Ricky Gervais said, if we got rid of all of the scientific literature in the world, it burned somehow, we would actually come back to the same conclusions, or we should, or something very similar, because we would run the same studies and it would be self correcting. So that's a beautiful thing about science.

Dr. Holger Cramer: 39:16

Yeah, absolutely. I totally agree. Many people think that doing a systematic review must be completely boring because you just sit at your computer and you put together other people's work, but I think it's also a way to do something beautiful. So you're not doing your own original study, but You're really collating the things other people have done, and you see there might be gaps in this study, and so you add them from another source, and you put it all together to get a larger picture. And it's also a very creative way, if you have some affinity to numbers, of course, you need that. And it's a very beautiful way to really get one step closer to what might be the truth.

Matt Huy: 39:58

Yeah, and it's definitely needed. I wonder what got you into studying yoga? Are you a yogi yourself?

Dr. Holger Cramer: 40:07

Um, of course, I think everybody who's doing more than just a single occasion, uh, occasional yoga study has some own experience. So I actually, uh, started practicing yoga in my early twenties. And actually my, uh, I was, I was meditating. So I practiced. Uh, some forms of meditation, but then my later wife took me into a yoga class and I really recognized that it's something different to just meditation. Um, and, uh, very fast while doing yoga, I got rid of my neck pain that I had for several years and it really accompanied my adolescence. Um, and I really recognized I could not just relax more, but I also got pain free. And this was really an interesting experience because physiotherapy did not really help with my neck pain, but yoga did on a relatively fast pace. And then I, it was while I was studying psychology at university, and then I decided I wanted to do my PhD. And I had the chance to join a complementary medicine research team. And one of the topics they were working on was neck pain. And that was quite interesting because my own experience with yoga was that it helped for neck pain. And so I was able to, to really do. My first yoga study on yoga for neck pain to really see whether my anecdotal knowledge that it helped myself could be replicated in a randomized controlled trial. And it actually did. So it was really quite helpful, not only for low back pain, but also for neck pain. And, uh, that's where I really, I would say, catch fire. And I really recognize that There are a lot of things people think yoga might be helpful with. I think this is something that is the most fascinating with yoga, that the breadth of potential indications and applications is so much broader than, for example, with forms of exercise. And it starts with chronic pain, with mental health, lifestyle conditions, up to schizophrenia, where there are also trials looking at whether yoga might help with schizophrenia. And so I really experienced it as a really rewarding and interesting field of research. And this is also how I finally entered complementary medicine research.

Matt Huy: 42:34

Great. So you just mentioned other forms of exercise. And on a physiological level, the adaptations you would experience as a new yogi are similar to the adaptations you'd experience if you, you know, just did Pilates or I don't know, you did some weight training even. And a lot of the benefits that we see of exercise are across the board. And there have been plenty of studies that have looked at, you know, the effects of various types of exercise on, for example, low back pain. And it seems like what is best is just that people get moving. And it almost doesn't matter the form of exercise that you choose, whether it's rowing, weightlifting, yoga, or Pilates, they all seem to help to some degree. And the differences between actually the exercise forms is negligible. But you just said there that yoga seems to be better than other exercise forms for certain things. So could you go into that a little bit more?

Dr. Holger Cramer: 43:35

Um, overall you're, you're totally right. So, um, for low back pain and also for, um, conditions that are associated with the sedentary lifestyle for all those, it's important to get active. And this is also what good guidelines, for example, follow back pain recommend. They say. Get active, uh, get off the sofa and do some, some sports, some exercise, yoga, Pilates, and studies normally show that there are no so big differences. And I think this is really fantastic. So when I speak about that to, uh, yoga teachers or also yoga practitioners, they're often a bit sad to hear it because they think yoga should be more effective in studies. But I think for people who suffer from a certain disease, it's a fantastic news. because we all know that many people like doing yoga and for many people it's really joyful and it's easy to do but there are also some people who are uncomfortable with doing yoga and even more so who would never put their feet into yoga studio and we now of course speak mainly of male persons um who say no I would not try yoga and they don't have to so if they just want to get rid of their back pain for example they can do yoga other forms of exercise. And perhaps they would also not do Pilates also, that's also has a good evidence, but they could do weightlifting, they could do running, and it's much better than doing nothing. And we have, uh, very rare, um, areas where we can really say yoga is more effective than other forms of physical activity. So there is some evidence for mental health, for example, for depression, that yoga might be more effective than other forms of physical activity. And this likely is because it combines physical activity with breathing and with, with meditation. And that's why we might see an additive effect, but overall we have very little evidence that yoga per se is more effective than other forms of physical activity. What we see, for example, with low back pain and neck pain is that people who practice yoga not only experience changes on the mat, so only in the yoga studio, but they also experience changes in their everyday life. So, for example, they recognize when they have a bad posture. So, for chronic neck pain, for example, is strongly associated with the so called forward head posture. So, they really bend forward and in order to see something on the screen, they look in it, they then raise their head. And this is a really good way to get neck pain to do it. Um, and we see in, uh, research that people who practice yoga more easily recognize such unhealthy postures in daily life and they might correct them. And it could be, but we don't know for sure, it could be that this increases the long term effectiveness of yoga because you not only, for example, release muscle tense and you change cortisol level by practicing breathing exercises, but you might also change the way Do you sit and stand in daily life? And this might, might then have a longer term effect, but we don't know for sure yet.

Matt Huy: 47:02

Hmm. Well, that, that's definitely interesting to hear. Um, I know there's been quite a bit of research to suggest posture or quote unquote bad posture does not cause low back pain in terms of, you know, people can have an, a more exaggerated, lumbar curve in their in their lower back, they could have a more exaggerated kyphotic curve in their thoracic spine, the upper back, and that's not necessarily causing low back pain, but you are saying neck posture is associated with increased neck pain.

Dr. Holger Cramer: 47:37

It's, it's also not completely clear. So, pain generally is a very complex biopsychosocial, um, construct, and it's, um, consists of, of local changes. So we have some changes in the muscles, like muscle tension. Um, we have also changes in emotions, how I react to pain, for example, and how I, um, judge pain. And it's also social in a way that when I, for example, catastrophize minor pain, that I might step back from social activities, step back from, uh, so social, activities going out. Um, and this all can exacerbate each other. and it's not completely clear what causes neck and low back pain in the first place, as far as I understand it. But you're totally right. It's definitely not just posture, but it might be some part. And this is what. Patients report that it helps them when they, uh, perceive their posture getting bad in, uh, in everyday life. But you're totally right. Especially pain is a very fascinating conglomerate of different causes, symptoms, and then pathways how things get worse and worse.

Matt Huy: 48:58

Yeah, well, naturally, when I was doing my dissertation and, you know, talking about pain injuries, I went down the pain science rabbit hole. Just last week, I conducted an online workshop about pain, actually, looking at the biopsychosocial model and the fear avoidance model, which you were just mentioning, like how we get afraid of doing meaningful activities and how that can contribute to our pain, how pain is multifactorial. And it's interesting that you just said, if I heard this correctly, basically, it might not be the change in posture that might make a difference to someone's neck pain, but actually the belief that they are doing something positive towards their posture that might improve their pain?

Dr. Holger Cramer: 49:39

I, I don't know. It's just, it's just the first thing. Um, as I understand science posture makes a difference. So it's, it's not that it's, the one single cause, but that it's associated with pain and it can exacerbate pain. Um, but of course the, um, perception that I can do something about my pain is of utmost importance. So you mentioned the fear avoidance model something people experience while doing yoga or other forms of exercise is: I can do things that might lower my pain. So thereby you can increase self efficacy expectations and you can change, um, locus of control to say, okay, it's me that can, that I can do something. Um, and it's, I think it's the same about things I can do in daily life that when I, when I recognize that I do something that increases my pain, that I am able to change it, so it's not a fate I have to live with, but I can do something against my pain. And from psychological perspectives, this is a really important thing people learn, and it might change the way they approach pain, and it might reduce the avoidance due to pain.

Matt Huy: 50:56

Great. I love how you added that nuance to it. And in my reading of the scientific literature, you know, there's so much nuance to our body, to pain, to our physiology. You know, we are not machines, you know, with pulleys, Pulling things and breaking down like machines. You know, in one way, our muscles are connected to the tendons, which pull the bones, and those are a bit like a pulling machine. But when you look at the actual physiology of how things work, and chronic pain, and dysfunction, and posture, it becomes this messy biological thing where it's not as clear cut as we like to think. So I like how you, how you painted that, that picture of nuance, of, of, of lots of different factors affecting our physiology, our biology.

Dr. Holger Cramer: 51:44

So, one thing that was really important for me to learn is that even from a physiological perspective, when I say something hurts and I can't stand it anymore, for example, I injured my knee and my knee is hurting and I can't stand it anymore. I'm not feeling the pain in my knee. I'm feeling it in my brain. So it's really the representation in my brain that is pain. There is some tissue damage in my knee, but I don't really feel it. I feel it in my brain. And also the idea that it's unbearable is also in my brain. So even when I look from a very strict, rigorous physiological perspective, it's still not the periphery that is, uh, that is feeling painful, but it's my brain. It's very centralized and it's Um, when, when I feel this for a long time, then also the brain changes and we also have neuroplasticity there. And when I really catastrophize, so for a long time, it changes. to in a way that catastrophizing pain is getting easier. And if I, uh, if I train to look at it differently, I also can train it the other way around. And so this, for me, this really changed perspective just to, to really look at it. It's always the, the, the brain and my mind that is saying, okay, this is painful. It's never the knee itself.

Matt Huy: 53:09

Hmm. A central question in yoga is the question of,"Who am I?" And a lot of people will say yoga is about understanding yourself better, getting to know your true self. And I absolutely love how through science, through studying physiology, anatomy, biology, biomechanics, we can actually get to know ourselves better. And like this information to hear that tissue damage, and pain are not the same thing. They're not even necessarily correlated one to one and actually how I catastrophize, if I think the worst will happen, that can contribute to my pain. Knowing that information can, I think, can be really helpful. Very empowering, very enlightening, and it's this beautiful yoking of science and, and ancient philosophies of yoga.

Dr. Holger Cramer: 54:03

Absolutely. So, of course, um, at least the science I do can do little to answer the question who we are. So it's, uh, There is yoga study looking at it, even from a more quantitative scientific approach, not, not just from Indology philosophy, for example. So there are people who look more from a psychological perspective to see how connection to ourself, to spirituality changes. So there is science doing that. We're more in a prosaic approach to really look on whether yoga can be helpful with, with health, but even there we see. That things like, um, body awareness, and what we looked at as postural awareness, so to see How is the position of my body, but also, um, how is my body feeling? How are my inner organs feeling? Am I hungry? Am I getting ill, for example? Um, we also see from research that yoga can help to increase this awareness, so that people who practice yoga a lot have a better connection to the body, at least, to see they're easier in predicting getting ill and they respect more the needs and barriers of the body. So even there on a very minor level, we see that, as you said, getting to know ourselves a bit more might be a part of how yoga helps with health conditions. So it's, it's not just doing some exercise, but it's also getting a better connection to the body.

Matt Huy: 55:38

Yeah, I think so getting to know ourselves, it can be a spiritual thing. But even just knowing about how our bodies adapt to exercise, to know that tendons get stronger, to know that, you know, even by stressing ligaments and cartilage in my body, they actually will respond favorably for me, that is knowing myself. That is knowing how my body works so that I can go out and do my best yoga practice or even live my best life. So, yeah, I think, in this way, even knowledge of physiology can be really empowering and understand ourselves better. Brilliant. So could I ask, what are you currently working on? You mentioned that systematic review on yoga for depression coming out. Soon. So you heard it here first on our podcast. Look out for that on the Google Scholar. What else are you working on?

Dr. Holger Cramer: 56:25

Yeah, so the update should be out very soon. We have just published another systematic review on yoga and stress. So, um, when most people hear about positive effects of yoga, they think of yoga can release stress. Um, but We were surprised to see that there was not a single systematic review or meta analysis on yoga for stress. So we did the first one and also based on clinical studies, um, yes, yoga can help with feeling stressed. Uh, we're doing a few more systematic reviews on, on asthma and, um, uh, type two diabetes, so also updates of earlier ones, and we currently have one ongoing randomized controlled trial. on yoga for post Covid fatigue. So we, um, took the knowledge we have from, from cancer, so we know very well that cancer is, I'm sorry, that yoga is very powerful in relieving cancer related fatigue. And definitely, post COVID fatigue is different to cancer related fatigue, so it's different Pathways, some are the same, some are different, and many people have a much higher level of fatigue associated with post COVID. But still, we thought yoga might be a good idea also for post COVID, and for fatigue, and for depression, and also like physical, symptoms associated with post COVID. And we compare yoga to health education, so to just giving information in a very structured way. And this is what is often done, for example, in rehabilitation for post COVID. And the study is ongoing, it's a multi center study, and we have completed about half of the patients. So we are in the very middle of the study and we expect results by mid 2026.

Matt Huy: 58:24

Brilliant. And, you know, I think just the fact that you're conducting this research in relation to yoga, so that people like me can then disseminate this information and then yoga teachers can share this evidence based information. It's so powerful. So again, I think we as the yoga community are indebted to you, even though I'm sure most of you, 99. 9 percent of all yoga teachers will never have heard of you because you are in academia. We can all be grateful for the work that you've done and that you're continuing to do. So thank you again.

Dr. Holger Cramer: 58:58

Yeah, so you're so very welcome. And also I can only give this compliment back because of course it's important to do the research and to collate evidence, but it would not at all be useful if it would not be used in clinical practice. So it would, I would still love to do it, but it will not have, would not have any impact. So I think we all depend on each other. So, um, it's, it's good for you to, to see the evidence, and to be able to bring it back into clinical practice. But without you, and without the community of yoga teachers, yoga therapists, and yoga practitioners, the work we do would also not be useful at all. So, thanks to you and to the community, too.

Matt Huy: 59:38

Great. Good. All that's left for you to do, I think, is to eventually write a book to compile all the information that you you've gained in your lifetime. Have you thought about this before?

Dr. Holger Cramer: 59:49

Uh, I, I thought about it and it might happen, but not too soon, I think.

Matt Huy: 59:56

You're too much in the trenches of the research itself, right?

Dr. Holger Cramer: 1:00:01

Yeah, and I just changed positions, um, about two, two years ago and I built up a fantastic research group. So research is always a team sport. And I, the first thing it was to build up the research group and now we're. We've really started, we're doing great things, but it will, of course, take some time until I feel completely settled here in southern Germany. And then there might be some time to, to really start writing the book.

Matt Huy: 1:00:29

Okay. Until then, I'll keep looking out for your studies on Google Scholar. And it is in my bucket list to have my name on a scientific study. So if you need a research hand remotely, let me know.

Dr. Holger Cramer: 1:00:42

Okay. I will. Thank you. Matt.

Matt Huy: 1:00:45

Okay, brilliant. Well, thank you very much, Holger. It's been great to chat with you.

Dr. Holger Cramer: 1:00:49

You're very welcome. And I have to thank you for the opportunity to share our findings.

Matt Huy: 1:00:54

Awesome. Thank you. All right. Take care.

Saz: 1:00:59

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