Gender Differences with Tendon Adaptation

: On today's episode, gender differences with tendon adaptation. Welcome to the podcast helping you overcome your proximal hamstring tendinopathy. This podcast is designed to help you understand this condition, learn the most effective evidence-based treatments and. bust the widespread misconceptions. My name is Brodie Sharp. I'm an online physiotherapist, recreational athlete, creator of the Run Smarter series and a chronic proximal hamstring tendinopathy battler. Whether you are an athlete or not, this podcast will educate and empower you in taking the right steps to overcome this horrible condition. So let's give you the right knowledge along with practical takeaways in today's lesson. Welcome back. Thanks for joining me on another episode. Um, today I have an episode from the Run Smarter podcast, which I did a couple of months ago, and it actually originated from a PhD Q and A, which I explained in the episode. I also mentioned the launch of my YouTube channel, which has been going strong for about six weeks now, but I thought I'd keep it in just in case you're interested in wanting to subscribe to the YouTube channel, but the remainder of the episode covers the differences. between men and women when it comes to tendon adaptation. That being how they are maybe susceptible to tendinopathies or how they respond differently to rehabilitation and heavy load and building up strength, those sorts of things, and I found it incredibly fascinating. So hope you enjoy. The YouTube channel has officially launched. If you're on my email list, you would have received an email as well to let you know, and a little button to click to take you to the YouTube channel. It has been probably three or four weeks of planning, filming, editing, and yeah, excited to finally just release it and see what you all think. Um, I've never been huge onto YouTube. I've used it as like a search engine. Um, the five. You know, have some, for example, like audio equipment or audio set up and just anything really, if I need to fix something in my house, I'll usually just quickly YouTube something. Um, and never really like subscribe to any channels, but now since starting my own YouTube channel, I decided over the last couple of weeks to subscribe to a few channels and sort of get an idea of what I like that they do. And what. sort of ideas of what I can do for my channels in terms of how to talk, how to display things, how to show things, what they do in the intros, in the outros. And I'm actually really enjoying YouTube. I've subscribed to a few physio ones, a few running ones, a few kind of like entertainment ones and just subscribing to the channel and getting notifications of when a new video is launched on their channel and giving it a watch, putting it at two times speed, just having a look at what they have to say. Yeah, I'm actually really enjoying it. So, um, it's been a new, I guess, avenue and opened my eyes to a new way to use YouTube and hopefully you guys find the same. I know obviously a lot of you will be purely podcast specific. Um, but maybe make the leap across. Maybe you are already onto YouTube and really enjoy it. So take a chance, have a look at a couple of my videos. And if you do enjoy it, then hit subscribe, get notified when. episodes come out. Obviously, if you like the content of the podcast, you're going to love the content of the YouTube channel. The current videos that I have, I put a list on social media, mainly around running technique to start with. I'll see if I can find it again, just scrolling down through my feed. So there is three cadence videos. One around what is good running cadence, two is around should cadence change with running speed. three, how to increase your running cadence. Sorry, there's a fourth one here as well. Will increasing your cadence reduce your risk of injury? Or if you are injured, will increasing your cadence help with that as well? Then I decided to do three more videos around running technique. Reviewed a paper by Chris Bremer to show five traits that runners might elicit that may increase their risk of injury, talking about crossover step widths, talking about heel strike versus forefoot striking. And if it's okay, Does it cause injuries? Does it hinder performance? Those sorts of things. Um, so I thought to those, I thought having about seven or eight videos before actually releasing the channel was a good idea, so you could get a better, um, better idea if you like the channel, if it's something that you want to see more of and then hit subscribe, if you like what you see so far, and I will have the idea to release, you know, injury specific stuff. to show you things, show you rehab exercises, show you about certain like taping or pain locations. It's almost freeing in a way that I can actually show you things now rather than just tell you things. And yeah, I'd like to hear what you want to see on the YouTube channel as well. Like I said, if you follow me on social media, I did have the question in there on the post. If you... want to submit any ideas or any, if you have any ideas for future YouTube videos, uh, let me know. Cause then I'll just gather all those ideas and start putting together some, start categorizing them a little bit. I know YouTube has, um, I can't remember what they're called, like, um, just category sections in the YouTube channel so you can easily find content. And yeah, I'll start filling it out. I talked to triathlon Taryn, who is a podcast up, but also big in the YouTube space. And he did say about, you know, 75 to a hundred videos. Um, once you've got that, that's when you have a real YouTube channel. That's like the increase in the odds for something to go viral and then get a lot of subscribers, but, um, that will take a fair bit of time. Hopefully with the loyal run, smarter scholars that have amassed over the past couple of years that jump straight over to the YouTube channel, hopefully that helps at least build some momentum in the early days. And who knows, who knows where it takes me. I always just have an idea, run with it, see if it's worthwhile, see if you enjoy it and if I enjoy it, we'll see where it takes us moving on to another paper that I have done today. So two episodes in a row. Hopefully you like me releasing these papers. Cause last time I was talking about shoe, uh, running characteristics, shoe softness in related to running injuries. But. Today was an interesting one. I was preparing for a episode, a Q and a episode on the overcoming proximal hamstring tendinopathy podcast, which is the second podcast that I do. And someone mentioned, um, a paper about the differences between male and female tendons and how they adapt and how their rehab should be different. And it was a question, um, but referring to that paper and I hadn't seen it before, and so I asked, can you share. the paper and she was lovely enough to tag me in the post that mentioned that paper. And so I tracked it down and it's got some really interesting stuff, some things that you might, well, I found interesting. Hopefully you find interesting as well. And the lead author is Peter Magnuson and the title is the adaptability of tendon to loading differs in men and women. And I will go through a few different sections cause they They sort of have an hypothesis and they test out the tendons of men and women in sort of different domains. And so we'll go into each of those now. But in the introduction, it says, it is well established that women are more likely to sustain certain connective tissue injuries than men during physical activities. And yet the underlying reason for this gender specific difference in connective tissue injury remains an enigma. Estrogen receptor activity is modulated by and this is an important, um, I guess hormone that they talk about in this paper. It's called estradiol and seems to have a, um, direct relationship with tendons. So just remember that estradiol is apparently a receptor or a hormone that's sort of linked with estrogen. And so I continue. Extrigen receptor activity is modulated by estradiol. And studies show that estradiol has an inhibiting effect upon collagen formation in ligaments, which gives us reason to believe that tendon tissue adaptation to mechanical loading may differ between men and women. We investigated whether the gender differences exists in regards to resting and exercise induced collagen synthesis, which collagen synthesis is just like the adaptation process. tissue mechanical properties and morphology of human tendons. So mechanical property is just being like how strong and how it operates under load, I guess. And morphology would just be the size and shape of the tendon. And to what extent this is influenced by circulating levels of estradiol. So that's just the introduction, sort of their hypothesis and what they've decided to do within this paper. And the first category they have is tendon size. and physical training. So looking at the morphology of it and the hypertrophy of a certain tendon compared to men and women. The paper says, if long-term exercise produces tendon hypertrophy, that's what should happen. You know, you adapt it to a tendon, you get stronger, you start lifting heavier. As you start lifting heavier, the body gets stronger and the tendon hopefully undergoes hypertrophy, gets bigger. So if long-term exercise produces tendon hypertrophy, it would result in a lower stress on the tendon and thereby reduce the risk of injury. So it gets bigger, we can then put more force through it, it can withstand a lot more, and therefore when you go for a run or if you do some gym exercises, it lowers the risk of that tendon exceeding its capacity, I guess you could say. We therefore used an MRI to determine the cross-sectional area of the patella tendon, so the tendon at the front of your knee, in well-trained men and women. and they put in brackets running approximately 50 Ks per week over the last five years. Untrained age and gender matched individuals served as control. So they used people who aren't trained, who don't run and use them as controls. So trained men had significantly larger patella tendons in their cross-sectional area than untrained men. As you would expect, if they train, if they build up their capacity, their tendons are bigger. However, a similar difference could not be detected between trained and untrained women. This suggests that the human patella tendon in men adapts to regular physical activity by hypertrophy, while similar exercise had no detectable impact on the tendon size in women consistent with gender specific tendon adaptation. So when talking about tendon size and physical training, if you look at a... trained male, untrained male. The trained male has bigger tendons, but if you look at a trained female and an untrained female, well with the patellar tendon in particular, it seems like the tendon size and shape is the same or no significant difference. Interesting finding, the next category was tendon collagen synthesis and mechanical loading. So like I said before, tendon collagen synthesis is just the adaptation response. It is once a tendon has been subject to exercise, the sort of response after that exercise in order to get stronger and adapt and have that adaptation process, move through effectively after the bout of mechanical loading. So they looked at those things and said, to further explore the possible gender specific collagen response to loading, we determined the rate of protein synthesis of patellar tendon collagen at rest and 72 hours after a one-legged kicking exercise. So they did some sort of loading to the patellar tendon, looked at, well, looked at it at rest, looked at what the tendon was doing in terms of its adaptation, then subjected to exercise and then 72 hours later looked again and see if there's much of a difference. of collagen was markedly lower in women compared to the levels they have previously measured in men. Men have an elevated protein synthesis rate in response to exercise, but here we show that women do not respond to exercise with an elevated protein synthesis rate. So I guess in men what they've shown is, you know, you look at a tendon, you put through a bout of exercise, you look at the tendon again and you can see all these the synthesis rate, the rate of adaptability occurring, but then they have a look at it in women. Beforehand, do some exercise, look at it afterwards and doesn't seem to show much difference. The paper continues, interestingly, there was a tendency towards an elevated collagen synthesis in women when tested in the early follicular phase of the menstrual cycle when the level of estradiol was low. So they saw that, you know, The tendon after exercise in women didn't really show too much, but there was a tendency towards this collagen synthesis rate increasing, which is a good thing, but it was only in women, while it was higher in women, when they were in a particular phase of the menstrual cycle when that estradiol was low. And they said it was in the earlier follicular phase. And me reading this paper would suggest that the estradiol in that particular phase if estradiol is really low, then in other phases of the menstrual cycle when estradiol is high, therefore the synthesis phase, that adaptation phase is a little bit more hindered because of that circulating hormone. The paper continues, this data gave further support to the notion that gender and therefore hormonal milieu may influence connective tissue adaptability to physical exercise. This is an interesting paragraph. And it says that post menopausal women have a greater Achilles tendon cross-sectional area than young women, although they load their tendons less as indicated by their reduced muscle strength. This apparent contradiction may have related to the reduced inhibiting effect of estradiol oncologen synthesis. So for those who are postmenopausal and don't have high levels of estradiol, even though they're not loading their tendons as much as they did premenopausal, their tendons are looking bigger with more cross-sectional area. They continue to more specifically study if circulating estradiol levels influence the human collagen synthesis response to a cube out of exercise, we measured the marker of collagen synthesis in women taking the oral contraceptive pill and those who did not. Non-users of oral contraceptives tested in their early follicular phase of the menstrual cycle, responded to the bout of exercise with an elevated collagen synthesis. Whereas the oral contraceptive users that have elevated circulating levels of estradiol did not demonstrate any change. So it does seem that whether, you know, if you are postmenopausal and don't have this high circulating estradiol, or if you are taking oral contraceptives and therefore have a decreased estradiol levels, then the collagen synthesis would be larger. So interesting to find that's not just age, but also medication that you're taking. This data extends the notion that estradiol can influence collagen. metabolism by reducing the acute exercise induced response of collagen synthesis. So, so far we've looked at tendon size to physical activity. We've looked at this collagen adaptation phase after mechanical loading. The third and final thing that they looked at was mechanical properties of the human tendon. So looking at what physical properties, um, strain strength, the tendon has. They say. To explore if the observed gender specific differences in collagen synthesis and hypertrophy also meant that there were differences in tissue strength, we formulated mechanical testing of single isolated collagen fascicles obtained during elective surgery. So they put in brackets here, anterior cruciate ligament reconstruction. So during an ACL reconstruction, it seems like they took the anterior portion of the patellar tendon of young men and women. they looked at the collagen fascicles and they said that the fascicles were approximately 330, whatever that unit of measurement is. Um, so it seems like the fascicles were the same kind of diameter or same size. Um, and they were used in a mechanical rig. So they just put them under stretch or under strain tension. Collagen fascicles from men reached greater ultimate strength than those from women. These results. suggests that in addition to gender specific differences in tendon collagen metabolism, there is also differences in the mechanical properties of the tendon fascicles. The extracellular component responsible for the distinction in mechanical properties remains unknown, but differences in the collagen diameter within the human tendon may leave it to be more susceptible to injury and is therefore a likely explanation. So, It seems like the faticle itself was the same sort of diameter, but, and then they put it under strain and saw that men have a more ultimate stress than women. But interesting finding. So they say in conclusion, habitual training resulted in a larger patellar tendon in men, but not women. Following an acute bout of exercise, men had an elevated tendon collagen synthesis rate compared to women. Moreover, circulating estrogen inhibited the acute exercise-related increase in tendon collagen synthesis. Finally, the mechanical strength of isolated collagen fascicles from men surpassed that of women. Collectively, this data shows that women have a lower rate of new connective tissue formation in tendon tissue, respond less to mechanical loading, and have a lower mechanical strength. which may leave the tissue more susceptible to injury. This podcast is sponsored by the Run Smarter series. If you wanna take your knowledge building to the next level, I have built out a proximal hamstring tendinopathy video course, which complements the podcast perfectly. Sometimes it's tough delivering concepts and exercises through an audio format. So the course brings a visual component, full of rehab exercise examples, graphs, and visual displays to enhance your understanding. Even if you sign up now, you'll have access to all current and future modules that I create. Sign up through my link in the show notes, then download the Run Smarter app, and you'll instantly have unlimited access to all the course resources on any device. And to say thanks for being a podcast listener, I want to give you a VIP offer. There will be a link in the show notes in every episode that will provide you 50% off the course price. Just click on the link and it will automatically apply your 50% discount. Okay, so to finish this paper, I thought of coming up with a few final takeaways or my interpretation or advice after reading this particular paper. Number one, definitely consider these differences, especially when you're comparing yourself to others, comparing yourself to other athletes, not only just to male to female, but oral contraceptive versus non oral contraceptive versus premenopausal. post-menopausal, phases of your menstrual cycle, all these sorts of things need to be considered when you're trying, or if you decide to compare yourself to others. If you are running in a training group and everyone's sort of training the same, if you're with a group of people, say work colleagues, and they're all preparing for a marathon, or if you are injured and you're looking for answers, if someone has a tendon injury and you're looking for advice and... someone says, oh, I did this to rehab my tendon, this really worked and doesn't necessarily work for you when you're trying to wonder why. All these differences play a huge factor and this is only considering male versus female. There's so many other differences of why tendon adaptation would respond differently to one versus another. So always just consider that. The next point I have is just to consider a more conservative buildup with your strength training or with your running volumes. if you are susceptible to a soft tissue or tendon injuries. Um, I guess when I wrote this down, it's like, I guess it doesn't matter if you're male or female anyway, but I guess highlighting this for females as a reason why you should be more conservative. Um, if you have noticed in the past, in the last, you know, 12 to 24 months, you have had several tendon issues or tendon injuries or struggling to rehab from a tendon issue. You just need to consider that a more gradual strength training program, a more gradual buildup to prepare for a race or a more gradual buildup in your rehab may need to be considered based on what this paper has shown. Start for most people between 10 and 15% of a ramp up per week. For those who are not injured, if you have a race to prepare for and your goal is to sort of build up your running volumes. generally start between 10 and 15%. Most people follow that 10% rule. I say, you know, depending on some, that might be too conservative. So just hover between 10 and 15%, whether that be your weekly mileage or your weekly trim, your training impulse, which I've discussed on the podcast before, that might fluctuate here and there. You might start at 10% and build up 10% week by week and feel really good. and decide to stay at 10% or if you're feeling like really good and you feel like it's too gradual, maybe just knock that up to 15%. But if you notice that a buildup of 10% is like starting to get a bit sore, starting to get a bit stiff, you might want to start taking that back down or have a recovery week and then go back up to 10% or you might want to try and find an 8% increase week by week. It's just all about giving some give or take depending on how the body's responding. And lastly, I'll say this shouldn't concern anyone. Like the findings of this paper should actually highlight the importance, which is actually good to know, but shouldn't spark any fear, anxiety, worry, because if your training levels are fine, this won't rupture or damage tendons. There's no sign of that. It's just looking at, um, a slightly weaker, less ability to adapt. but everything should still be really safe grounds, provided that your loads are introduced gradually and adjustments are made if you're showing early signs of soreness or pain or fatigue. And as long as you're sensible in your training, this will be safe grounds. But like I said, if you're starting to notice early signs of tendon soreness or tendon stiffness, maybe with your first few steps in the morning, take action early. And if you take effective action early, there really shouldn't be anything to worry about. That's all I have today. You can now go check out the YouTube channel. You can go subscribe. I'll leave a link in the show notes, but on the YouTube search bar, you can search run smarter with Brody sharp and should be right there. Hit subscribe and looking forward to seeing what the next journey is. Thanks once again for listening and taking control of your rehab. If you are a runner and love learning through the podcast format, then go ahead and check out the Run Smarter podcast, hosted by me. I'll include the link along with all the other links mentioned today in the show notes. So open up your device, click on the show description, and all the links will be there waiting for you. Congratulations on paving your way forward towards an empowering, pain-free future, and remember to stay safe. Knowledge is power.