24 Tendon injuries

Hello and welcome to the High Performance Physiology Podcast. I'm Chris Beardsley. I'm here with my co-host Rob Marcery. I'm going to follow on from last week's episode on muscle strain injury by talking about tendon damage and tendon injuries. Now obviously tendon injuries or actual injuries in general aren't our specialisation where basically kind of interested in the muscle physiology and the implications of that for strength training programs. But we need to be aware that there is an overlap between kind of injuries that do happen in sport and the kind of strength training programs that we are writing. So what we're going to talk about today is the kind of two main types of tendon injury that you're likely to see, which is tendon opathy and tendon rupture and how that might happen as a result of what's going on inside the muscle tendon unit and the types of exercise and training that we're doing. So broadly speaking tendon opathes are often assumed and I'm going to make this assumption in this podcast. So if people don't agree with this assumption then you can basically just ignore everything that I'm going to say about tendon opathy. But we're going to make the assumption or I'm going to make the assumption that tendon opathy follows naturally from large amounts of tendon damage. So that's kind of my starting assumption. So if that assumption doesn't sit well with you, then that's totally cool. You can stop this now I guess and follow whatever protocol you think is most appropriate. So the protocol we're going to work with basically is that tendon damage causes, if it's you know reaches this sufficient, it's physically high level, it's going to cause a tendon opathy and therefore we can kind of look at tendon damage which is actually relatively well understood. Whereas tendon opathy itself is a little bit harder to get your arms around. So we're going to work with tendon damage as being the thing that we're kind of focusing on. And the same I'm going to make the same assumption regarding tendon ruptures. I'm going to make the assumption it's essentially a tendon rupture is an extreme case of tendon damage either acutely or as we talked about last time muscle strain injuries, that is the accumulation of large amounts of damage leading ultimately to a rupture in the same way that muscle strain injuries ultimately are the accumulation of tiny damage kind of areas that ultimately lead to a entire muscle strain. So those are the assumptions that I'm making now as I say. I think these assumptions are pretty good assumptions but I'm not going to sort of argue with people who say that they don't agree with them. I'm just going to say cool fine then use the different model but it's totally cool. So assuming that is the case then tendon damage actually is relatively straightforward. We know from a number of very very well done laboratory experiments that the cause of tendon damage is excessive strain and recoil of the tendon. So this is really really important because what you tend to find when it comes to tendons is that people assume that higher forces are the problem and actually because of the way that because of the fact that tendons are viscoelastic tendons actually tend to strain less when you expose them to really high forces in vivo. So if you're doing not only in vivo but in practical situations in vivo because you can kind of create a scenario in vivo where the tendon will kind of strain and I have a response to large forces but generally speaking it's not really normal for us to behave like that. In strength training where you're kind of grabbing the bar and lifting it or when you're in sport you're producing a high force to slightly slow speed then generally speaking the tendon is going to behave in a very stiff way that's viscoelasticity and as a result it's not going to have that very large strain. In contrast if you're doing a lighter kind of low movement or body weight style movement generally speaking the tendon will strain it will actually strain and recoil quite a lot. Now in most endurance activities like for example a classic one obviously is endurance running and endurance running you will see that people who have a more compliant tendon will display a larger movement of that tendon in the kind of running gate cycle and as a result that ends up creating a large number of events every footfall in which your tendon is moving back with a forward straining and recoiling and that's going to create you know successive damage with every footfall that you're creating. You do some strength training and you start stiffening the tendon you start to see less stretch and recoil of that tendon you start to see less obviously tendon damage occurring and then obviously you can kind of predict what's going to go on from there. So the interesting thing is as a result when we look at the incidence of tendon up these again working with the model that tendon up these kind of following on from muscle from tendon damage ultimately you tend to see that the biggest incidence of tendon up these is in the endurance kind of activity community you sort of say you know long distance running and yet at least 10 up the you also see in the context of things like kind of track and field where you all say for example team sports we have a lot of vertical jumping that's why we've got things like jumpers knee in the kind of vocabulary that we use because people who do a lot of jumping tend to end up with kind of pretend not to be so the interesting thing is that we're starting to see then that tendon up these are very common in circumstances where people are doing a lot of repetitions of these very light load or body weight type load activities where the tendon is actually stretching recoiling you don't see the same thing in situations where people are doing high volumes of heavy strengthening activities it's not so common yes you can find people who've got tendon up these associated with those kind of things I don't think it's the same thing but I think what you're seeing here with the endurance activities or large amount of volumes of plyometric activities tend to be associated with that ten up these literally just the large numbers of strains and recoils of the tendon creates tendon damage which then creates a kind of situation we end up with a tendon up thing now tendon ruptures are a little bit different I think that's probably more likely something where you accumulated a lot of damage and then you've probably exposed the tendon to a high force but being damaged and accumulation of damage you end up with a rupture situation interestingly the most common tendon ruptures most common situation with tendon ruptures happening is actually in the usage of anabolic steroids so I went through the literature while back I was shocked really shocked I wrote a table together with all the data because they use a number of different statistical comparisons to talk about groups of people who then go on to experience an injury and then you kind of do a ratio of the number of injuries in one group versus the number of injuries in the other group and when they're looking at tendon ruptures it's really interesting because sometimes when they're comparing a non-user of anabolic group and a user of anabolic group sometimes they can't do a statistical comparison because there are no incidents as of tendon rupture in the group that's not taking anabolic steroids you kind of go okay that's quite suggestive so ultimately anabolic steroids really really big kind of contributor towards a risk of any kind of tendon rupture and that's really interesting because when you start to look at what steroids are actually doing they're tending to upregulate synthesis of things and down regulate breakdown of things so if you look at the I mean that's fundamentally what they're doing so if you look at the muscle itself then you up regulate muscle proteins synthesis you down regulate muscle protein breakdown generally speaking on a muscular level both in terms of hypertrophy and also in terms of damage repair that's generally a good thing because you're increasing the amount of live-rippled proteins that you're making and you're decreasing the amount that are being broken down now I think that probably has got a tiny pathological element to it because I do think the breakdown processes are important and actually serve you know in a key sort of actually activity inside the muscle we need that but I think that the the balance of processes does lean heavily on the synthesis side of making new proteins I think that's why anabolic fundamentally don't create huge problems on a muscular level the problem is when you look at tendons when we actually experience tendon adaptions especially after strength training we're not actually adding any more collagen so the balance of synthesis to breakdowns is very very different so now we don't need to add loads more collagen to create extra stiffness we actually don't create more stiffness than a tendon from adding more collagen we do it by restructuring the tendon and that relies much more on breakdown to do the restructuring than on the synthesis so essentially the anabolic is making it much harder for the tendon to reorganize itself because it's stopping you using the breakdown process that are actually essential to actually doing that reorganization so ultimately I think that is why we see much bigger problems with anabolic steroids in the tendon context compared to the muscle context I don't think it's because they don't exist in the muscle context I think they do exist in the muscle context I think there's the balance of problem versus kind of benefit if you like and no moral judgment implied whatsoever but like the kind of physiological level the kind of the kind of what you're getting positively and what you're getting negatively kind of skewed in favor positively at least as far as recovery and hypertrophy are concerned but in terms of the tendon I think it's the opposite I think you're skewing much much more in the direction of it not being a good idea now just to be clear a lot of very kind of influential voices regarding tendon kind of adaptions don't kind of follow these ideas and a lot of people talk about anabolic similarly follow these ideas they say that ultimately the reason that the kind of anabolic usage causes tendon rupture is because the muscle grows in strength faster than the tendon I'm not fundamentally opposed to that specific idea but I don't think it's the main reason why things go wrong I think that you see these kind of issues irrespective of whether I mean ultimately the only way in my view that that would happen would be if the tendon rupture happened very, very early on in someone's kind of bodybuilding career when they started using antibiotics, when the strength gains, the muscle side gains were really, really fast, or alternatively if the bodybuilder was exclusively using relatively light loads and wasn't able to create a tendon adaption at all. I think in no scenario, sure, you might end up having an imbalance between muscle strength and tendon stiffness. So it's that you start ripping the tendon literally off because the muscles too strong for the tendon. But don't think that is what is happening normally. I think what's actually happening normally is that the antibiotics have fundamentally disrupting the breakdown processes and therefore disrupting the reorganization that allows the tendon to restructure itself. And that's why the data we've got shows that tenders just don't structure themselves, restructuring themselves properly in subjects that are using antibiotics to as a near-served people. The data is obviously an animal. It's not going to be ethical to get that kind of thing through research environment. But, you know, basically that's kind of the problem that I think we're seeing with animal experience. Anyway, so what I'm saying, just to wrap this up, is tendon damage, I think, is the ultimate base cause of both tendon up to the end tendon rupture. That's my assumption. In that case, we can just look at what causes tendon damage. It's basically lots and lots of repetitions of body weight or light load type activities involving a large amount of stretch and recoil. So stretch shortening cycle type activities. So any kind of endurance running type activity, something like that, any kind of plyometric activity done in sufficient volumes, that's going to create problems. On the other side, stopping that from happening or at least moving in the direction of helping ourselves prevent that from happening, what we're going to want is to make the tendon a lot stiffer so it doesn't stretch and recoil. Or totally, which is obviously not do those things in the first place. But like, assuming you are going to do those things, let's assume you are, like, for example, in a deer, it's runner and you want to do a lot of running. You want to avoid a kiddie's tendon up there. Or let's say you're at a kind of a, under no basketball player or, you know, someone else trekking field is using a lot of vertical jumping. Then yeah, we want to make sure that tendon doesn't move around quite so much. Accepting that, having a good stretch shortening cycle means that you will want it to move around. So we've got that kind of balance to work around. And we talked about that in the stretch shortening cycle episode that we did previously. But fundamentally, what we're saying here is that, you know, we could use the strength training as like a way to stiffen the tendon. But we need to use a load that is at least 10 right max or heavier. Now I think that as the athlete progresses, they're going to start to need a heavier and heavier load. And I think it's going to come down to five right max before you start to see changes because we do see very, very kind of strong plateau's in tenderness to changes after only a couple of months of strength training. So 10 right max, I think is the kind of the starting point we need to be heavier than as heavy and that as heavy as that or heavier. But fundamentally, you know, kind of as athletes progress, I think we probably need to go slightly heavier than that. That's kind of where we are. Basically, there's a type of activity that increases or excise increases tendon damage. And there's a type of activity that decreases it. And you can kind of therefore see where we're going in terms of balancing when athletes have got to do a lot of plyometrics or a lot of plyometric type activity in their sport. All their endurance runners or something like that. And we can use that heavy strength training as a way to start to reduce the risks of tendon damage happening. Hopefully, therefore, assuming the model works, reducing the risk of tendon up to the or tendon rupture as well. Subjects to the tendon actually being able to adapt because the person is not taking animal X steroids. I mean, obviously there's something you can't actually work around. I mean, that is just a problem that people are going to have to accept and you know, think about ways in which they can mitigate that. But fundamentally, you know, assuming that's what they want to do. So that is the physiological introduction, really took a long one this time, lots of stuff as to work through. But now, going to ask Rob, there's lots of things going on here Rob. So I've got a number of questions I want to ask you about the programs that you're writing and in no particular order. Obviously, one of the things that is a risk factor for tendon damage happening, one of the things that does cause tendon damage happening is the plyometric movements themselves. So we've talked about how a high performance physiology kind of workout plan would start with speed and do the method. The method, yeah. So we'd start with speed, then do heavy strength training, then do kind of plyometric activities, then finalize with super max, these entries all in the same workout in order to get the best kind of training frequency for everything. But when we've talked about some of your programs in the past, often you drop out the straight shortening cycle component of that fork component framework because it's just simply either unnecessary or you don't want to do it all year round. So can you talk a little bit about when you're doing plued, some plyometrics in your programs and give us an idea of how much volume you're doing with those? Yeah, definitely. So I think for the most part, yeah, like you said, I don't tend to do a ton all year and sometimes obviously none at all. Really what I'm going to include them the most is maybe in the generally about six to eight weeks leading up to when I would kind of need that adaptation to be maximized in terms of volumes for myself and for any of the athletes that I coach. I'm always using, honestly, a pretty low volume of plyometric work from doing something like the repeat calf hops or the straight leg and things like that. Maybe just a few sets of five or so, honestly, it's not a ton. And all I'm going to do at that point is just monitor if someone is improving and that's it. And if the dose is such that they're improving in a way I want them to, I'm just not ever going to increase it because if people are playing a lot, you know, playing a lot of games, running, jumping from me, skateboarding, all these things, you know, if I'm improving and I don't have pain, I don't have any sign of any, any tendent damage, tendent opathy, those things creeping up. And then I don't really see any reason to increase it and I'll just ride it out as long as I can. I guess maybe in theory, I could get a little more out of a little more, but, you know, I'm not really that worried about it. Like I said, as long as someone's improving, I'll just keep it at very minimal dose. Frequency was once it's in there, I will do it usually every session, sometimes every other session, but just depends. But again, it's not a ton like in any one workout. So really at that point, I don't see a reason not to include it frequently. And then again, just monitoring, you know, the athletes and how they're responding and just going from there. We have very, very low volume compared to, you know, I've certainly seen some protocols where it's a lot of landing phases, a lot, a lot of reps. We talked about one for the podcast that was, you know, like 50 to 80 in a week and things like that. I don't see any reason that would be beneficial and you'd have to be pretty special to be getting away with that on top of your game play and your daily activities to not see some damage creep up. Yeah, absolutely. And just kind of to be clear for people who perhaps haven't listened to our stretch shortening cycle episode, the what we're trying to do with a climatric is produce an increase in the eccentric strength of the movement relative to the tendons stiffness of the muscles involved. Because ultimately, if you can get the eccentric force of the muscle to pull the tendon around, you'll get a stretch and recall the tendon. If the opposite happens and the tendons stiffness over powers, essentially is stiffer than the eccentric force of the muscle, then you won't get the tendon moving around in that particular context. So this is really interesting because the stretch shortening cycle that we're trying to improve doesn't really have a single adaption. It's there's no unique adaption associated with it's literally just eccentric strength, which we're getting elsewhere anyway and tendons stiffness, which we're getting elsewhere. Anyway, so the whole this is one of those really, really valuable moments where we can say, look, this is why we don't think about outcomes without also knowing what the underlying adaptions are. So when somebody says, oh, when I'm trying to improve speed, my brain straight straight away goes, okay, well, there's a list of these adaptions that contribute to speed. Somebody says, I'm trying to improve power. I'm like, okay, hang on a minute. Now, this isn't going to work because speed actually and strength are the two things under pin power. Power's a second order effect. So now, if you want to improve power, you've got to tell me how you're doing it either by speed improvements or strength improvements or both. You can't do it directly. So straight to way again, this is exactly the same thing. Straight shortening cycle, like, oh, I'm improving my straight shortening cycle. And like, okay, well, how are you doing it then? Are you making the eccentric strength of the muscle bigger relative to the tendons stiffness and what are you doing to make that happen? It's really interesting because when you showed me that kind of set of social media posts that you've been collating to shock me with, it was basically lots and lots of very, very sub-maximal straight shortening cycle movements. Now, technically, yeah. And we kind of went around and circled a little bit so that we could say, like, does this fit the definition of plyometric because you need an impact phase. But from a practical point of view, the impact phases were so kind of low in terms of the force generated. And the level of effort was so low in terms of the subsequent movement that it kind of felt it was almost not really plyometric, even though hours time, the definition's technically always got an impact phase. And it's a straight shortening cycle. So it kind of technically is plyometric. But the level of effort was so low, it was like, what is actually going on here? So I think not much. Not much. So this is the problem when people kind of get, oh, I'm going to do a straight shortening cycle exercise and I'm going to improve my straight shortening cycle performance. And this is a plyometric and like, okay, yeah, but how are you increasing your eccentric strength relative to time as stiffness? Because if the thing that you're doing isn't doing that, it's not going to work. And this is why I mean, incidentally, the This is why we put them third and not second after speed stuff because ultimately they are an eccentric movement. The thing that changes your straight-shawning cycle is what happens in the eccentric phase. And this then ties into the other important thing which is that you're already doing a bunch of speed stuff right to the beginning of the workout. A lot of people think that plyometrics, yeah exactly. A lot of people think that plyometrics are about improving speed. Well hang on, that's not what's going on here. It's not what's going on here. The plyometrics is about improving the eccentric strength of muscle relative to tendon stiffness so that you can get a better straight-shawning cycle effect. Yes, that will enhance your ability to move quickly because you're slowing down the muscle shortening velocity relative to the joint angular velocity. That's what the actual tendon movement is doing for you when you've got it. But it doesn't mean that your exercise is a speed exercise. People get really tripped up on that with the pliers. And the other thing is, there's a lot of gears messy. Pylewise, I still see a lot of people as well. They think they need to increase tendon stiffness and they do like you were saying. But then they think that the plyo increases stiffness. This is a very old myth. It is a very old myth. It's still big and it's still around in some big education and things that I've seen and some big certification bodies. Yeah, so recently in a very popular certification body. This is very frustrating to me because this is one of those things where this information is really easy to verify literally just work through the current plyometrics literature. Look at how tendons adapt and the answer just drops out into a lap. It's very straightforward. A lot of people get hung up, I think, on whether certifications are recognized or not, for example. But the problem is a lot of certifications, even if they are being recognized, even if they are being issued by high profile organizations, they aren't updating for the research of the last 10 or even 20 years. So you're looking at information that was kind of current 20, 30, 40 years ago. And we've got some amazing physiological data from the last decade, especially on plyometrics, which completely reverses everything that most test and Z-Coaches will say about what plyometrics are doing. A lot of yeah, we're increasing tendons stiffness. Well, not really. We've got a whole bunch of plyometric studies showing that you don't increase tendons stiffness. And even if you do increase it slightly, strength training produces increases and stiffness below it out of the water. I mean, it's just mad. So really not the special thing about plyometrics. The special thing about plyometrics is the ratio of eccentric strength gains to tendons stiffness. It's an eccentric strength training exercise that doesn't really create some of the other force related adaptions like hypertrophy and whatever else is going on inside. I'm not going to kind of go down that route route right now, but ultimately you kind of what you're doing is a very short sharp eccentric stimulus that is going to create some of the eccentric related or uniquely eccentric related adaptions. And that's going to then lay to pull the tendon around without stiffening the tendon itself, which would come with the more kind of force strength related adaptions. So this is really important. You know, you are programming speed stuff, but you're turning to drop out the stretch warning cycle stuff, and only including it in the periods of time when you think it's going to make the most difference because otherwise you're just going to be exposing that. Yeah, huge amounts of stretching we call all the time exactly the same thing that's going to give you the benefit is the thing that when you do too much is going to, you know, thank you. And then the long term and cause the damage. So just yeah, don't see any reason to have a ton of it and have it in all year. Sure. So one of the other things that I think is interesting here is that in the research isometric contractions tend to be better at increasing tendance stiffness and dynamic ones. Now there's a number of kind of potential explanations for this. I think the most obvious explanation is simply that if you kind of do a set of muscular contractions, then afterwards the tendon is going to have to do two things or it's going to want to do two things. It's going to want to adapt by increasing his stiffness, as long as the stimulus was there to do that. And it's going to need to do any damage repair that you've produced. Now the issue is that isometrics probably don't produce very much damage at all because they're getting almost no strain in record. Whereas dynamics always will have a little bit of damage. So I think you think about in terms of budget constraints. Yeah. Basically the tendon can do two things and if it hasn't got to do very much damage repair, you're going to get more on the stimulus adaption side. So I think that's really what's going on. The isometrics are probably just not having to do the other sort of damage repair stuff that dynamics are doing. Now I know that you've used isometrics a lot in various contexts. So just by way of kind of giving people a bit more information on that, can you just run us through some of the isometric contractions, even if that you're programming, even if they're not explicitly for the purposes of increasing tenders, and as stiffness, but just so that we kind of see an insight into your programming of isometrics the moon. Yeah. Yeah. I mean, I do I love isometrics. I use a ton of them. And in terms of like I actually have used them specifically for Achilles. I've got these things that I've got before because I I wrecked mine doing some endurance running after not running for years with my wife, which was awful. But so I just will start out with the Achilles end of things. So when I'm using isometrics for the Achilles, you know, the main things they have to be heavy, they have to be very heavy. And they should be in a stretch position, so like a much more dorsiflex foot position. I see people a lot of the time trying to do them, like a seated calf raise, you know, holding the squeeze, holding the top where they get a lot of feeling in the contraction. And the loading there compared to a more bottom range straight like calf raise is just going to be nowhere near where you need to really cause like those beneficial adaptations in the tendon. Achilles are really like very heavy, you know, like three, four, five second isometric contractions, just in that bottom range when go very, very heavy and know that I'm actually getting, you know, on load like a significant load through the tendon to cause that adaptation. I'm really like those and for me personally and for people I've used them with, I've seen a lot of benefit when they've had issues with Achilles tendon and stuff like that. And obviously you're going to get some, you know, calf strength, calf growth and things like that. So I guess if you're trying to avoid hypertrophy, maybe not, but in the case of like improving tendon stiffness and using them to like help and Achilles tendon those work really really well. Cool. So in terms of just, you know, like seconds or how are you kind of kind of controlling that dosage? I mean, are you counting? Are you using counterstopwatch? And it just a few, you know, usually like three or four, three to five second contractions in a set. And then I might do, you know, two, maybe three, the very most. It's not very many. Again, it's not a ton of volume on these things. If I'm doing them, it's going to be either again, every workout or every other workout. But those I've seen really, really good changes with. And again, it's not like I'm, you know, monitoring the actual structural changes in the time. No, sure. It's just. Yeah. No, and even pain symptoms and stuff like that. Generally see a really good benefit with that. Cool. So that was actually obviously the perfect example because it's literally for the purpose that we've been talking about today. But in terms of other ice metrics, I need you to ice metrics for the hip when you've got a hip action. Kind of strength and strengthening requirement. You do those on a bench, if I remember. Yeah, those will be usually kneeling on a bench and a few different positions. So one more extended position. One a bit more flexed around mid range. And then one in like a fully flexed hip just to get the different hip flexors there. Get the wrecked fam and then get the the so as muscles. Same thing again, you know, like hard as I can three to five seconds, just a few contractions per set. A lot of times I'll include those in the warm up just because you know, people don't have on the hip flex one particularly people don't have a great hip flexion machine or anything like that. Easy to just do those on a bench knock them out at the beginning of the session. And then they're good. And then you know, the other one I use a lot in terms of isometrics is going to be just quads. We talked a bit about it on a thing other than the bioelfting podcast or a different one. We using them for increasing recruitment. Just like a single like knee extension. So and then for the you know, tell or tendon and that those are going to be you know about your your best bet like just a seated knee extension going very heavy. So I was just thinking as you're saying that the when we talked about hip flexion in the past you mentioned using the lying leg machine as a hip flexion dynamic. I guess you could do those single leg and set the weight so that you couldn't move them and do them as well. So you actually do the same thing there and create a padded I mean because obviously sometimes the bench isn't very comfortable. Yeah, so I guess if you if you want that extra degree of comfort then you can use I guess a lying leg. I could totally do that and I'm like which I have not done but just because I have pretty nice patches. Sure sure. Yeah, but that would be a great option because yeah, I mean also it doesn't take it's not a movement you're using it's on a weight on it anyway. So it doesn't take very much, you don't have to go very far. on the stack to get a way that you're just not going to move in that inflection. So yeah, what do you use that to do for most people? Have you ever programmed or have you done yourself any, I know you have, because we don't, but last week actually after the podcast, have you done any upper body isometric stuff? Yeah, so obviously so. I'll mention those maybe after, but I've done for the pecs, I've done just some like single-arm pec fly isometrics for the purpose of increasing recruitment in the pecs there. If you did have something going on with your pectendins, some of that, you could absolutely use those. Same thing, I generally go heavy just a few seconds. Honestly, I don't, I don't use a ton of long duration isometrics. Just the population of people I work with and myself, it's not something I usually see much of a need for you, maybe like a rehab setting when you can't go heavy yet, you know, you're paying all kinds of things, then I might look like more of a long duration, I so especially with like Patelia tendon and maybe Achilles and that. But for me, you know, most of what I'll talk about here, what I do is just kind of heavy brief isometrics for the purposes of recruitment and then tendon stiffness and all those things. And they're all going to be similar terms of number of contractions, number sets, things like that. And in terms of the intensity, are you going from maximal intent? Because when you mentioned recruitment, I'm thinking you're going from maximal intensity. Any, any, any asymmetric I'm doing, I'm going as, as hard as I can, you know. Okay. I'm always going very, very heavy on them. You can use a ton of load on them. So, you know, yeah, this is interesting to me because I played around with asymmetrics last summer. And I was surprised that different dysmetrics at different parts of the body produced very in me, very different perceptive responses. So perceptual responses. So for me, low body and pressing movements aren't so bad. But pulling just absolutely destroys me. I have no idea why. I mean, it may just be my kind of personal, I said history of one on kind of chins. But like for me, as soon as I started pulling something as hard as I possibly could, I thought my arms were going to get ripped off. I really did. It feels very strange. It feels very different from the other. I get imagine it would be horrible. It's one of those things where when I'm pulling dynamically, then obviously you kind of set your rep range or whatever. And I'm kind of usually working in sort of 5, 7, 6, 2, 8, whatever. And yeah, sure, by the time I get to the final repetition, yes, I'm pulling maximally. And that doesn't feel like a problem. But when I start un-fatieved and I'm like, okay, I'm not going to pull as hard as I possibly can. It just feels totally different. And it's quite, and it's not in the sense of power lifting because I've kind of done that. I know what that feels like. That doesn't feel like this. This feels to me different. You know, the only thing I've done comparable, I guess, loading-wise that I mess around with a little bit. I've done really heavy, like, single arm hangs, just to mess around for fun, just like, you know, for grips strength, whatever, maybe. And I definitely do feel like my arm is going to pull off. That's probably because it is. I guess I would imagine that if you're doing a really heavy point, I so kind of feels similar to that, which does feel miserable. So I can imagine. Yeah. It's for me just felt different. I don't know whether that is just a feature of the pulling motion, or whether it's just my history in that area. But anyway, if other people have insights into that, then obviously, please do let me know. But yeah, so, okay, cool. So, yeah, you've given us, for example, there are various different isometrics you're using. You've talked about kind of the dosages that you're using, which I think is very logical, actually, kind of ties in with standard dosages of heavy strength training, which is appropriate because that's pretty much what it is. Really, it's basically doing exactly the same thing. A lot of people get confused because that isometric. It's not dynamic. It's like, well, really, biologically, it's pretty much exactly the same thing. Tiny little differences here and there, but fundamentally, you can treat it as more or less the same. Cool. Okay. So in terms of coming back to the basic theme of what we've been trying to communicate today, tendon damage is probably at least in the model of well working with the responsible cause for tonnopthes and tendon ruptures. So we're going to kind of try and manage that tendon damage two ways of doing that or to limit the amount of plyometric activity if we're programming it. Obviously, if it's part of the sport, that's not something we can control. It's have to be aware of it. On the other hand, on the other hand, we can obviously do heavier strength training, keeping the loads heavy or using ourometrics, you know, for the specific areas that tend to understand how likely to be negatively affected. And as you said, you can program those in a variety of places. Now, again, this is like a sophisticated version of the high performance physiology method, but essentially, you can put those isometrics if you want to. If you're not doing too many of them, you can put them in speed section. Yep. But otherwise, you know, and what I probably would do is put them towards the end of the speed section and it would be kind of naturally grading into their strength training section because that's the other place where you put them. Yeah, because I'll always do the jump work in that first before those. So they would follow that. Yeah, I'm not doing those before the actual max speed stuff. Yeah. Yeah. And I guess that probably we can come back to that when we talk about pronunciation mechanisms in the future because ultimately, I think a lot of people are using the Potentiation Effect, whether it's the post-actuation, Potentiation Effect, the PAP Effect, whether it's the post-actuation performance enhancement effect, PAP effect, most people are using those incorrectly because they're making assumptions about how they work. That's not correct, or the aren't correct. And we've been passing a link back, which was in forwards over the last week or so, about a particular individual who should know better. Oh, man. Who keeps writing articles, very detailed articles about how to use these Potentiation Effects and it's just not how they work. But anyway, so we will do a full explanation of Potentiation or as some people call it priming and just explain exactly what's going on there in a future episode. But hopefully that has been useful today. We've carried on from talking about muscle strain injuries last time, talking about tendon injuries today. We will come back with another episode next time on a completely different topic.