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Expand your running knowledge, identify running misconceptions and become a faster, healthier, SMARTER runner. Let Brodie Sharpe become your new running guide as he teaches you powerful injury insights from his many years as a physiotherapist while also interviewing the best running gurus in the world. This is ideal for injured runners & runners looking for injury prevention and elevated performance. So, take full advantage by starting at season 1 where Brodie teaches you THE TOP PRINCIPLES TO OVERCOME ANY RUNNING INJURY and let’s begin your run smarter journey.
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In today's episode, the cartilage response to running with Michaela Kahn. Welcome to the podcast helping you train, rehab and run smarter. When I first started running in my 20s, I knew it would be something I'd be passionate about for the rest of my life. But, unfortunately, developing injury after injury disrupted my progress and left me under-trained at the start line on race day. Even with my knowledge as a physio, I still fell victim to the vicious injury cycle and when searching for answers, struggled to decipher between common running myths and evidence-based guidance. That's what this podcast is here to help you with. So join me as a run smarter scholar and let's break the injury cycle by raising your running IQ and achieving running feats you never thought possible. Welcome back run smarter scholars you're going to really love this episode Michaela is a researcher. I came across a paper on Twitter I have like a list of Twitter followers like a bit of a group and it's a whole bunch of. Running researchers and things and a lot of papers come up and I'm like, this one's really interesting. It was released in 2022 and the title was the influence of running on lower limb cartilage, it was a systematic review and meta analysis. And I saw in the author, um, list of all the authors over there, JFS school. Yeah. Who's been on the podcast several times and, um, I have his email. So I reached out to him and said, Hey, uh, would any of your authors be interested in talking about this paper because I think it's really interesting and put me onto Michaela who was the head author of this paper and I love giving you access to research, recent research that debunks myths that has practical takeaways for you and you know most of these papers hardly see the light of day and the fact that it's such a good paper and I the author and share it with you scholars, I think is a fantastic thing. Makeda was grateful enough to share her time, very passionate. She's studying at the University of British Columbia and she studies all things running biomechanics, her bio, it's, she's, her research is previously in biomechanics, but this one takes a little bit of a different, different route as well as what she's working on in the future, but it was great to have a conversation with her and give you a bit more insight into what the most recent research is. And so let's take it away. Michaela, thank you for joining me on the podcast. Thank you so much for having me. I am looking forward to learning more about you. So how about we start off with an introduction first particularly around like how you got involved into research and in particular, this certain topic of research. Sure. So I'll start from, I guess maybe the beginning when I was a kid. Let's do it. Yeah, so I mean, I ran cross country in high school and then for my local track and field club. And that's when I really fell in love with running and I was the kid that was like obsessed with running shoes and Disneyland was cool and stuff. But I like watched the Olympics and like going to track and field meets and all that. So fell in love with running and then. And I don't think I realized I could make it a job or I could actually study it until much later. But then I went and did my bachelor's degree or my undergrad and my master's degree in kinesiology at Western University in Canada. And my MSc was mostly focused on like clinical biomechanics, so long-term outcomes of Achilles tendon rupture. And then I met one of my mentors, J.F. Yep. He's been on the podcast a few times. For sure. So I met him at a conference and I was like, wow, this is cool. I didn't realize this was a job. So I kind of followed him out to Vancouver and here I am doing running research. Wow. Excellent. And outside of research now, do you still get involved in running and events and that sort of stuff? I do. Yeah. So I'm a recreational runner myself. Like I was never a super, super really fast runner. I mostly do triathlons nowadays because I do one sport well when you can do like three media really. So that keeps me busy. But Vancouver is just, I live in Vancouver and it's such a great place to run. Lots of trails around here, tons of races, great running community. So very great to be out here. Do you gravitate towards any certain distance of triathlons? Mostly the sprint. I am not quite built for endurance. I played a lot of like team sports. played varsity squash in my undergrad and masters. So like the quick and dirty in and out, that works the best for me. Yeah. Yeah, great. It's tons of fun, the sprint distance. Absolutely. Okay. So the reason why I sort of reached down was really interested was your paper last year, which I've got the title in front of me, the influence of running on lower limb cartilage. And what got you involved in that? How did that whole topic start? Yeah, so this study was actually started, it predates me, I want to say maybe 2016, 2017, and it's because of again our friend JF, so he started it with James O'Donovan, who is a sport medicine doc in Dublin, Ireland, and then Jean-Sebastien Roy, who's a professor at the University of Laval in Quebec. So they started the study, and then I guess it hit a bit of a stand still. So when I turned up in like January, 2020 to start my PhD out here, JF very graciously offered it to me and asked if I could bring it over the finish line. And we brought a few more people onto the study and got her done. Wow. Okay. For the listeners, so most people listening are just recreational runners, they're not health professionals or anything like that. And the design of the study is a systematic review. meta analysis. Would you mind just explaining exactly what that is and how those sort of designs are structured? For sure. Yeah, systematic and systematic review and meta analysis is very researchy, big words. So break it down, basically, a systematic review is a paper that brings together the results of many other similar papers that are asking pretty much the same question. And we call it a systematic review because there's a lot of rules to writing the paper, so you have to go through like a systematic process. So basically you combine the results of a bunch of studies and there are more people altogether and that minimizes the bias, so it's more like truthful results, I would say. So in a systematic review, you might be able to say like, oh, a certain percentage of studies found that treatment A is better than treatment B, and then you can take that to doctors or clinicians for them. So you can go one step further by doing a meta-analysis, which is basically more of a statistical way of summarizing the results. So that's taking like the numbers. Whereas a systematic review might not include like the stats and all of that stuff. So meta-analyses are not always appropriate to do, but in this case, we were able to do one. Okay. Yeah. When I was at university, they were saying that like a systematic review is, you know, one of the highest quality studies, cause you're getting a whole bunch of other studies that share similar designs or similar questions and hypotheses and combining them together, which boosts up your sample size, it boosts up the and those sorts of things. But I guess, you know, in terms of a systematic review, it's only as strong as the articles you find for that answering that particular question. And when it comes to the meta-analyses, so when you do a systematic review, you don't actually take participants and put them through an exercise or an intervention or a placebo group or a control group, and then look at the findings, you're looking at studies that have already been done. and then saying, okay, based on the results of all these previous papers, once we compile it, what seems to be the general answer or conclusion that we come to, but that just might be, okay, this intervention is better than this intervention or better than placebo or better than a control group. But with the meta analysis, you're actually taking the data from each of these previous papers, and looking at the actual effects, the actual you know, how much effect there might be, and then sort of actually putting it onto a graph, I kind of imagine like it's all like one big table or one big visualization of getting all of these individual participants and then saying, look, this is the results now that we've gathered a whole bunch of studies and become a lot more sample size, a lot more of this is what we've found. Fair to say. That's exactly right. And there is for the meta analysis, there is a certain type of graph you use, and it's called a forest plot. And yeah, essentially, it's just like a big, big table. And if you're on the right side of a line, it means this. And if you're on the left side of the line, it means that. So exactly as you described. And very visually appealing for you to just like, it's hard work putting together meta analysis, but then to like, from someone stumbling upon this paper and look at a forest plot, it's very nicely, very succinct and very defined. So a lot of hard work I could imagine. Yeah, it was a good time. I think they say that systematic reviews take on average like 1.5 years to complete. Wow. So it's a pretty, all the hard work's been done for us, like other people have done the studies, but to put it all together, it's not an easy task. Yeah. And so when this was handed to you by JF, how much had it gone through the process? And so how much did you need to get it over the finish line? Yeah, so JF and crew, they've done a lot of hard work kind of getting the original research question together and then the second step after getting the research question together in a systematic review is searching databases for appropriate papers that fit the criteria. And so they had done a search and found some papers, but that search hadn't been updated. So we essentially had to kind of start again and research those databases. And then there ended up being about 50% more studies but a lot more needed to be added. But I'm very, very involved in the original team. Can you remember what the hypothesis or research question was when starting? Yeah, so basically, this study came about because there's still widespread belief that running ruins your joints. So we... Or so that basically, sometimes people won't start running because of that belief, or maybe they'll quit in hopes of like preserving the cartilage in their joints. So we just wanted to gather the current evidence on the role of rent or. Yeah, the role of running on cartilage properties to see where we're currently at. Cause we knew there were studies out there demonstrating it, but nobody had really pulled them all together before. Yeah. One thing like when you read a meta analysis, one thing I'm sympathetic to is looking at, okay, once we put in all our key terms and our key searches and uncover, you know, a thousand different articles. And then we have to filter through those and remove duplicates. Then we need to read the titles and quickly dismiss ones that aren't within our criteria. Then we need to read the abstracts and go through all of those. And all of, as you're reading the system, you can say, okay, filters down from a thousand down to 200 down to 80 down to 60, as you go through this process and sift through trying to find the ones that are relevant enough to know, fit into your systematic review. What did it end up filtering down to? How many papers did you end up at the end? 42. And that came from over 5000 titles that we screened. Wow. Duplicates went down to like, I think just under 5000. you have to read in more detail and then yeah we ended up with those 42. See you read a lot and you really get familiar with what's out there. Wow and I could imagine there's a lot that you can instantly dismiss like just by reading the title it'll be like you know done experiment done on rats or something you could just like quickly pass it on but then there's a lot there's some that you can be like okay now we have to read through the abstract and you know include that very time consuming and you kind of go cross-eyed staring at your computer screen. There's a software you can use to help screen articles and I always call it Tinder for researchers because you swipe left or right on it, whether the research is relevant or not. So it's pretty fun. Any sort of thing to try and gamify it, I guess, is getting some sort of enjoyment out of it. Yeah, basically. Otherwise, it's a pretty tedious project. Were you happy with the 42 coming back like in terms of that number? Yeah, 42 is pretty decent. Like I would say that's a good amount of studies for a systematic review. And the interesting thing is like a lot of different studies came back. Like there were some following runners that ran. a multi stage ultra marathon, there were some looking at novice runners, some they had runners in shoes, some were barefoot, like there were all kinds of things that came back. Did you have a specific criteria about what type of participants would participate in these studies that you would then include? Just over 18. And I don't believe there are any studies in children. which might be interesting if somebody wants to do a new PhD out there. And were you looking at runners specifically or team sports, all of that? Yeah, runners specifically for this one. Some papers included other things like walking on flat ground or upstairs, but for this one, we just wanted to know about running. Okay. And professional runners, recreational runners, anywhere in between? All of the above. Okay. Great. Everybody from really, really beginner. Um, to again, there was one paper that followed runners from, there was like an ultra stage or sorry, multi-stage ultra marathon that either started in Norway and went down to Italy or the other way around, I can't remember now. But yeah, so pretty like we trained runners. Yeah. And so. these studies would have needed to follow like the outcome of like the response of the cartilage to these certain events. So maybe looking at the cartilage before and after a race or after a certain period of time to then, you know, see what the effects were like. Yeah, you got it. So the inclusion criteria was you had to look at people's joints before going for a run and a lot of variation within that. So for instance it could be after a single run, it could be after multiple runs or training program, one did like running experience of 10 years, and then for the after scan, it could be like immediately after the run. So you take somebody like straight from a treadmill into a scanner, or it was like, on the same day as the run a week after the run a month after the run. So everything in between. Wow. Okay. And based on these studies, well, I guess in the criteria as well, did you filtered down to a certain joint, because I could imagine the knees would be quite common, maybe the hips. Was there any others that you found or came across? Yeah, so the knee was definitely the most popular, I would say most of the studies looked at the knee joint. At the time, there were no studies that looked at the hip. But since the study's been, since our paper has been published, there's been one study looking at the hip. But the other joints were the ankle joint and then a few looking at cartilage in the foot as well. Okay. Did you think to yourself, oh damn, if only that hip study was around prior to our systematic review. As soon as it came out, I remember sending it to JF and being like, ah, so close. Oh damn. If only your systematic review took two and a half years to make instead of the one and a half years. I know, I know. Just needed more time. That's the thing as well, like, when all these studies come out, like whenever you do a systematic review, there's always going to be new publications that come out and those sorts of things. And, you know, you just got to take it to face value. Exactly. Usually with a, when you start a paper, you have a hypothesis, you have a question, and then you have a what we expect to kind of find. And, you know, you being around JF and all those other high credentialed people, I'm assuming that you would suspect that you know cartilage may not be detrimental to joints when it comes to running. Did you have any preconceived ideas or any hypotheses of what you might come across prior to collecting these studies? hypotheses prior to meeting JF. And then I had a different one after. Before I came into this research, I was a previous elite athlete in gymnastics and I was definitely told and suspected that my cartilage was totally worn out by the ripe old age of 18. So I was under the impression that running is bad for your joints, wear and tear and... distinctly remember like going to see a sport medicine doctor when I was like maybe 20, 21 and being like yeah I definitely have OA like I've worn away wow And they just looked at me like, what is she talking about? But it's because that narrative I heard all my life, like, yeah. They got you. Yeah. Oh, they totally got me. Um, so you can imagine to my surprise when I started reading these papers and talking more with JF, um, and my supervisor that I was clearly completely wrong. Okay. Yep. So they sort of opened up your eyes and sort of enlightened you to, um, current research, current understanding. And then. So you've sort of changed your understanding prior to this sort of study. Um, and so you've got the studies, you gathered them all, um, and you're starting to fit together the meta-analyses and that sort of stuff. Um, what sort of research is coming out? Like what, what are the results by the end of it? Yeah. So I should mention that, um, what we were looking for in cartilage specifically. We were looking at various different cartilage properties. So maybe I should start with like the cartilage is the smooth, soft tissue on the ends of your bones that allows them to slide over each other with not a lot of friction. And it also has like some shock absorbing properties. And so what we can do is use magnetic resonance imaging or MRI. we take pictures of inside your joints and then we can measure a few different things. So for instance, we can look at the thickness of the cartilage or like its volume and using really advanced techniques, we can even look at like protein concentration or water content of this cartilage. So what we found is like imaging people before and after a single run. If you place them in the scanner immediately after the run, yes, you will see some changes to your cartilage. So it might look a little bit thinner, the volume will be smaller, there's not as much water in the cartilage, and the protein content is a little bit changed. But the studies that scanned the participant later in the day, or a week after, or a month after... The cartilage pretty much went back to what it looked like before. So there weren't kind of these lasting changes. So immediately, yes, something changed, but then it seemed to return to normal. And that was the same after not just a single run, but also a training program or running for 10 years. So no, none of this lasting change. So it reminds me of, um, Like this is what I was told I don't know if this is true or not, but like the discs in your Your spine like they go through like at the end of the day. They have less water They're not as don't have as much volume. So you're actually taller like when you first wake up in the morning, just because there's more fluid and there's more things, but over the process of the day as you stand in there, it's sort of weight bearing and you're sort of moving around, it's depleting a lot of that volume and a lot of the water content within the discs. Do you think it might be something similar along those lines? Yeah, that's a really good example. So cartilage is a really special tissue in that it doesn't have a blood supply or a nerve supply, but it's essentially like a bag filled with water and cells and proteins and connective tissue. And so when you compress the cartilage, it acts like a sponge. And so it has these little pores in its membrane and the fluid inside the cartilage rushes out. And then when you relax your cartilage, so offload it, that water or fluid runs back into the cartilage. So sure, when you're running, you're pressing on the cartilage, it's acting like a sponge, water is rushing out of it, so you would expect changes in thickness and volume, water content, all the things I mentioned. But then when you rest it, it returns to normal. So it's all to do with fluid dynamics. Okay. Um, and so what's your overall conclusions when it comes to, you know, the summing up this whole paper, um, apart from what you've just described, is there anything like practical runners can take away or any reassurances that people can have or, um, yeah, things that can take away from it? Yeah, I would say, um, we're trying to remove the fear factor. That fear factor I had when I was 18 years old and thought I was just wearing away my joint. So from the research that we can say that in this kind of short to mid-term, running doesn't seem to cause long-lasting changes to cartilage, and the recovery after a run is still quite rapid. We do need more studies that look at the repeated exposure to running. So more of the studies in our review paper, they were looking at immediate changes and less looking at the running programs or 10 years of running experience. So there's still more work to be done in that area. But I think we can kind of comfortably say that as long as you're running within your own safe physiological range of cartilage health, your joints should be okay. Okay. How would you, how would you guide people around the physiological range? That's a question I don't fully know the answer to yet. So I mean, a lot of what we do is guided by pain, but as I mentioned, the cartilage itself, it doesn't have any nerves, so you don't really get a pain response from the cartilage itself. But it would be listening to other things in your body that are causing pain, so whether it be muscles, ligaments, tendons, something like that. think the safest thing to do is to build your tolerance level slowly. So there's our study we couldn't exactly, like we didn't have the statistical power to compare novice runners versus trained runners, but there is some evidence out there that the trained runners might have quote-unquote like stronger cartilage than people who don't run. because they've just been building it up over the years. So we call that cartilage conditioning. So not recommending anybody jumps off the couch and like runs a half marathon straight away. But it also means that you can build tolerance. And we used to think that cartilage wasn't really a tissue you could condition. But now we're starting to see otherwise. What's your idea, why do you think this whole myth started in the first place that running is bad for the joints and bad for cartilage? That's a really good question. And I was surprised at what I found. So basically, in the 70s, they had animal models. So they took like a pig or a cow, took their joints and mounted them on kind of a rig. And basically, pounded those joints over and over and over again and said, oh no, the cartilage breaks. But of course, these were one in animals and then two in dead animals. So the cartilage was not alive. It wasn't filled with water. Like. body couldn't adapt. What a poor design. And it was crazy to me that like, even after all those years, like we still hear that today. I still hear it when I tell people I'm like researching running and knee health, they're like, oh, terrible for your knees, blah, blah. And I'm like, oh, it's actually the opposite. Um, but yeah, it comes, a lot of it comes from those really old studies in the seventies. I didn't know there'd actually be studies to. to reference back to I always thought that a lot of, well, first of all, a lot of runners get knee pain. And so this is just like patella femoral pain, not necessarily to do much with the cartilage more to do with the kneecap joint itself. But if you have a lot of runners that get knee pain, they're like, oh, yeah, running's bad for you. But kind of combine that with a lot of people thinking that your body is like a car that just has car like just parts that need to be replaced that have certain mileage on them that need to get replaced after a certain amount it just deteriorates over time and all those sorts of things and you know even doctors they sort of buy into running's bad for your knees yep you're going to wear out that cartilage there's a certain mileage there's a certain expiry date on them if you put more mileage in with running it's going to wear out quicker if you have OA it's going to get worse you're going to eventually need a replacement and all those sorts of things. Thinking of very much like a static, um, non-responsive structure that, you know, just has an expiry date rather than what you're describing is like, it's a living breathing tissue that, you know, has fluid has proteins responds to load and all those sorts of things. Um, that's sort of like where my mind goes when talking about how this myth all got created in the first place. Um, I remember a large systematic review, I think it was looking at the prevalence of OA in runners and recreational runners and the sedentary population and those sorts of things and came across that recreational runners had a lower prevalence of osteoarthritis in the knees and hips compared to the sedentary population, which seems to suggest that maybe there is some sort of strengthening of the cartilage that goes on with the acts of running. After this particular research, would you have the same ideas or do you have other ideas around that hypothesis? Yeah, I think I'm not a physiologist, but it makes sense to me from a physiological perspective. And also because there are so many other benefits associated with running, like we know a risk factor for having arthritis is being heavier or knee injury or anything like that. So it's not surprising to me anymore that this... that recreational runners would have a lower incidence of OA because of now understanding the fluid dynamics. So when I mentioned the water or fluid rushing outside of the cartilage, when it comes back in it actually brings all the nutrients with it. So that's how the cartilage gets fed essentially because it doesn't have a blood supply. It has to rely on that exchange of fluid. between the joint space going back into the cartilage itself. So without that movement, so without the cartilage being squished like a sponge and then. water rushing back in, like a sedentary person. Yeah, that could cause some problems. So now it's no longer surprising to me. Yeah, going back to that prevalence study, they also factored in professional runners or elite runners, I think they called it which was extremely high tier you like were considered an elite runner if you got paid as a runner or if you represented your nation in whatever so like really, really top tier. had higher prevalence of OA. If I remember correctly, the recreational runner had about 3% prevalence of NeoA. The sedentary population was like 10% and the elite runners were somewhere around 10 or 12% or something like that. So back to your advice around... making sure you're running within something that's you know, physiological, physiologically acceptable within your tolerance levels and building up safely. Part of me suspects that okay, the sedentary population might be on the one side of the spectrum of really under loading themselves, maybe putting on a bit of weight, maybe deconditioned, maybe the, the muscles around the knee joint are fairly weakened, not really that robust. recreational runners are somewhere in between and the elite runners, maybe in their early days, have really pushed beyond their physiological limits and maybe overdone things. I'm just speculating here, but would that make sense? I think it would. I call it kind of. Goldilocks principle of cartilage. So if you remember like Goldilocks and the Three Bear story going into the house and like I think it was eating the soup or something, one was too hot, one was too cold, one was just right. There is probably a range that is just right. I wish I could look at people's cartilage and say yeah, you should run no more than like I don't know, a hundred K a week or 50 K a week for you when that's a pipe dream, I guess. But for right now, yeah, we know that recreational running is likely the healthiest. We don't know what the upper ceiling is, but results suggest that, yeah, obviously you have to build up to it. But then when we think of like the really, really elite runners, they're running to be fast at that moment in time and thinking less about the long-term effects. So yeah, potentially they aren't allowing for that cartilage to return to its original state and they're overloading that in the meantime. So, yeah. And like you said, there's, um, during that activity, the, the fluids pushed out, it's sort of, um, it's one way taking the fluid out to then eventually have the nutrients flow back in. But we know that, okay, there's a short period of time after a run that needs time to seep back in. What time it seems like we're unsure, it might be hours, it might be like along that timeframe, would we say? Yeah, so most of the studies, like Actually, I think most of the studies, if they scan the person within the same day, their cartilage was back to normal, but it did take like up to half an hour or at minimum half an hour to kind of seep back in. So what a lot of studies will do now, the participant will finish the run, they'll go in the MRI scanner and then just keep repeating the same scan over and over and over again for like an hour later. And then you can see it kind of almost in real time. from like the studies that we do. So we do the exact same thing. We take people downstairs to our MRI machine, we scan their knees, they come up to our labs, they'll run for half an hour on a treadmill, and then they'll go back downstairs like immediately into the MRI machine. You can even like see it on the screen, the cartilage is kind of puffing back up, and we scan for like 40 minutes half an hour would be that timeframe. Potential, that's for a healthy joint, I would say. And it depends on like age, sex, previous trauma, all these different things. Gotcha. But yeah, potentially as fast as half an hour. Okay, excellent. Let's get to a patron question, cause Rachel asked, how can I maintain healthy cartilage? Um, she understands as you know, strength and cardio and running all those sorts of things are good options, but is there anything else we could be doing to help get our college nice and strong and healthy? Yeah, good question. Um, so it sounds like a boring answer, but just like maintaining a healthy lifestyle is the best thing you can possibly do. Um, so again, risk factors for getting osteoarthritis and might be a previous knee injury, so try not to tear an ACL. Don't do anything to your menisci. Um, because that might put you at a higher risk. And then stuff like weight management, education, a well-balanced diet, moving within your physiological range and then gradually building your exercise tolerance as well would probably be the best things. Yeah, so building up your exercise tolerance to then potentially create that... stronger cartilage, like you said, that there may be that those long term adaptations. Yeah, potentially. There's a paper that came out in 2010. And they took novice runners, so kind of learned to run like couch to 5k runners. And they found evidence only in 10 people, though. So somebody needs to do a bigger study. But they found that the cartilage did in fact get stronger. With that. Yeah. learning to run. So there is potential for it. Great. I know this isn't around your field of study. I don't know. Feel free to say if you don't know the answer. But there's a lot of conversations around supplements and other sort of dietary options to take. Do you know if there's any research about medications and supplements that might help with cartilage? Yeah, the one I hear about the most is collagen. And I believe there is like some evidence that collagen supplements are like might do good for you. Not exactly my area of expertise, but I should look that up. But I've had participants that claim it's like saved their life, but I've had others that are like, yeah, that's pointless. So, okay, consult your healthcare practitioner. Spoken like a true researcher. Very good. Is there... Is there any worry for or like what might be some signs if someone were to be worried about their knees, say like a high mileage runner? Should they be extra careful about their knees, about their cartilage, about how they're training and those sorts of things? I think if you've gradually trained up to where you are, I probably not. But yeah, I worry about the runners that. said, oh I had an epiphany and I signed up for a marathon and it's in two weeks and I'm just gonna go do that. Those are the runners I worry about more. But if you are a seasoned runner, I'm... yeah, and no pain. I'm not as worried. As long as there's an understanding that... changes to your cartilage, it is a natural process of aging. So a lot of the time people get freaked out if they have any X-ray and all of a sudden the doctor tells them, Oh, by the way, you have osteoarthritis. And that's when people get a little bit scared or stop running or modify what they're doing. Um, but it is very, very normal. Hmm. Do you know if there's like how common? mild signs of osteoarthritis would be in a given population, like if you're 40 or 50 or 60 healthy population, what the prevalence is like? It raises every decade, but I think almost like 30. 30 to 50% of people over 40 will show signs on X-Ray, but that does not mean that they'll know about it. So I think only 30% of those will have pain to go with their changes on X-Ray. Yeah. This is what I'm concerned about with recreational runners who are none the wiser, who get knee pain when they run and it's... presenting like patellofemoral pain, but doctor doesn't know this out, let's send you for an x ray or let's send you for an MRI. And then it comes back with mild away. And they're like, oh, this is the source of my pain, I need to really lay off it, I need to let it rest, maybe running isn't for me, maybe I should try swimming instead. And all of these sort of myths around this whole thing, and the doctor might, you know, concur with them say, yeah, running is bad for your knees, stay off of we don't want this mild OA getting any worse, actually backing off and doing some non weight bearing exercises like swimming might actually be detrimental to their recovery and long term outcomes. And so it's good to have people reassured that if they do get scans, they have mild osteoarthritis that it's completely normal. And, you know, if only we could scan the other knee and say, Hey, there's mild osteoarthritis on this side too. But that's pain free and been totally healthy for my whole life. Exactly. The other thing, like, you know, if you have an MRI, they're going to scan for everything. I've had health professionals on the past talking about college and suggesting it's kind of like wrinkles, like you get wrinkles on your skin, perfectly normal sign of aging. Sometimes you scan the college and there's wrinkles, you know, and no one else would really bat an eyelash if you said, oh yeah, but it's just a healthy process of aging. I suspected a stress fracture in my mid foot a couple of years ago and I had an MRI just to be like, Oh, is it a stress fracture? Um, and they scanned for everything. They said I had mild osteoarthritis in my big toe. And I'm like, I do not need to know that because I've never had symptoms in my big toe. And I had this flash of worry being like, okay, I'm a runner. I have pretty minimalist shoes, pretty flexible in my, my big toe. Um, do I need to worry about them? Like, stop being silly Brody. Like, you know, you, you've interviewed so many people that, uh, you know what to do. You know how to think, but none the wiser runner can fall right into that trap. Oh, absolutely. Like, yeah, it's funny. You bring that personal story cause I have a very similar personal story. So I had hip surgery when I was like, yeah, 23, um, because I had like femoro, acetabular, and pinchman. And so I looked at my own- X-ray, which as like a researcher who can sort of read X-rays, it's like not a good thing to do. And so they were like, okay, this is the hip that we fixed. And I looked over to my other hip and I was like, wait, but that one's got the exact same thing. And my doctor was like, don't look at that. And like, he was like, you don't have pain, right? And I was like, no. sure enough, a week later, I developed some sort of like psychological pain in my other hip and I was like, oh my gosh, I'm gonna have to have another surgery, blah, blah. Since then, I sat myself down, had a good talk to myself, and I've never experienced pain since. Now, it's not often as easy as that, but it's just an example of, yeah, I saw something, I had a freak out, I had pain, and then it went away. So yeah, and now you can take that story and apply it to someone who's had pain just on the same side. And the fact that they've had knee pain, scan their knee, had a look at their scans on their knee, and the doctors explain the scans to them that could easily amplify pain because they're like, Oh my God, look at all this damage. Look at what's wrong. I'm never going to run again. And then that sort of perpetuates a whole cycle of pain and dysfunction and you know, worse long term like sort of pain trajectories and that sort of stuff. So again, reassuring that people have these sort of anecdotal things to know that the brain kind of freaks out a little bit when it comes to scans and looking at the structure and looking at all these changes and you can easily worry yourself into pain. Absolutely and the pain is so real. Like, if you're feeling pain, you're in pain like it's so real and Yeah, no, it's a really tough thing. That's a pain game. Yes. One, one last thing I wanted to touch on is like, what about for runners who do have osteoarthritis that maybe actually I would say is a little bit painful, but there's not a lot of pain receptors or anything in the cartilage themselves. Um, let's just say they, they're having like their moderate osteoarthritis and it's actually a bit more severe than the healthy general population because it does happen. If they're a runner, should they be concerned? What should they do in particular? That's a really good question and this is actually the topic of my PhD. So I'm looking at the response of arthritic cartilage to running. Do you want to come back on the podcast and talk about it? Give me a year and I'll come back and tell you what we found. So basically what studies here is we're doing, so people with knee osteoarthritis, we're doing that same like scanning before and after a single bout of running, but then also prescribing a 12-week running program aimed to increase mileage, and then scanning their knees again at the end. And so I don't have the data for that yet, so you'll have to stay tuned, but just from interacting with these runners, they've come in like... to our study with all sorts of different pain. So like 2 out of 10 pain, 3 out of 10 pain, all the way up to like 8 or 9 out of 10 pain, and all sorts of severities ranging from like mild, moderate, and we've had some severe as well. And I was worried when I started this that as soon as we started increasing their mileage, their pain would go up as well. But what we found is almost quite the opposite. So I would say most people's pain from start to finish has not changed. We've had people that have decreased their pain with an increase in mileage. We've also had people that maybe had a spike in their pain during the initial part, and then it's decreased. But that's from like week zero to week 12. In the middle, all sorts of things going on. So one day they have 9 out of 10 pain, one day they have 1 out of 10 pain, but over time... it doesn't increase. So I would say my best advice would be, yeah, pain may increase, but it also can come down. And it can do everything in between. So try not to be too discouraged if you're having like a bad day with your OA, because there will be good days as well, like expect the variation. I was listening to an old podcast, it was empowered beyond pain or something like that. And they were saying like with when it comes to cartilage and they were mainly referring to the lower back or those sorts of things, but like with these fluctuations in pain, it's not rational to think, oh, I'm having a bad cartilage day on one day, I'm having a good away day on the other day, like it doesn't really make a whole lot of sense as why there'd be such fluctuations in symptoms, but does mean well, it does demonstrate that pain is very much influenced by a whole bunch of other things. Even just, you know, even at week zero to week 12 of your study, if they're feeling a lot better, we can't essentially conclude that oh, it's because your cartilage is better. We can't really say that but what I think about when you say there's initial, initially there's some increase in pain and then there's some decrease in pain or sometimes people start running and actually decreases their pain. My mind goes to, well, maybe they're feeling a lot better about themselves that they're actually doing something active or they're actually doing what they love or they're actually being proactive and that helps. calm down their pain sensitivities. Um, and so I'm just thinking about your study design and all the influences that can be, uh, you know, involved. It's, it's very interesting and looking forward to seeing what the results are like. Yeah. I'm really. excited to. I'm a biomachinist by training but after this study we're doing qualitative interviews, we're doing surveys, because this pain experience has really opened our eyes that it's not all in the numbers. We could do biomechanics all day, we could look at the knee adduction moment, all sorts of things, what shoes they're wearing, what surface they're running on. But at the end of the day, like... these runners have come up with so many strategies and they've been so resilient. And honestly, quite stubborn. A lot of them, most of them have been told like don't run anymore. And they're like, Oh, I don't, I'm going to keep running. It's part of my lifestyle. Um, but there have been others as well that they are, they do feel grateful for the permission from us to run, I guess. Um, I had one guy. was so happy that we diagnosed him with OA because it explained his pain. Um, and he did really well in the running program. So there you go. Yeah. Very cool. Well, um, I could talk about this all day, uh, but before we finish up, are there any other final takeaways, any, anything from your research that recreational runners can do that we may not have discussed, um, anything come to mind? Yeah, so there are ways to alter the forces as you're running. So yeah, trial and error. Run on different surfaces, run in different shoes, see what fits best for you. But I think at the end of the day, don't be scared of running if you have healthy joints. Keep going. It's probably the best thing that you can do for your cartilage health. So I hope you enjoy doing it. And you love to. Yeah. And one of the interesting things as well, as you're saying that like the cartilage doesn't have nerves, doesn't have blood supply. So there's not going to be a direct, there's not going to be, not going to be a direct indicator to say that you've overloaded this joint because there's going to be soreness, but We can fall back on other signs and symptoms from structures around the cartilage like the joints and the ligaments and the everything to know that you are training within a good adaptation zone and you are building up gradually over time and fitting that adaptation sweet spot. So at least fall back on those symptoms to know that you are within training sensibly. Otherwise, unless someone has a fancy MRI access to an MRI scan to see what the college is doing, most people don't. But I think that's a nice takeaway as well. And I want to thank you for the long hours, the vigorous methods and all systems in place to put together such a great systematic review. I'll put a link up in the show notes to this particular study. And yeah, I want to thank you for all that time and effort you've spent and then coming onto the podcast and sharing the results. So thank you very much. I want to thank you too for bringing research to the people who can actually use it because we can sit in a lab and watch MRI pictures all day long but we need the information to get out there so thank you so much for sharing it. If you are struggling to overcome an injury you can jump on a free 20 minute injury chat with me which you can book through my calendar in the show notes. While you're in the show notes elevate your running IQ by jumping onto my free email list so you can receive material to help and increase your performance. If emails aren't for you, consider my Facebook group, Instagram and YouTube channels. 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