005 Stretch-shortening cycle

Hello and welcome to the High Performance Physiology Podcast. I'm Chris Beardley. I'm here with my co-host Rob Narseri and we're going to talk about the stretch shortening cycle today. Now this is probably going to be one of a couple of episodes in which we talk about the stretch shortening cycle. So the purpose of this one is to give a overview and explain what it is, what the underlying physiology mechanisms are and then just give some general recommendations focusing on the development of the stretch shortening cycle of the improvement of the stretch shortening cycle in high velocity movements. So as you'll find out as we just talk through this, there are a number of mechanisms that underpin the stretch shortening cycle, some of them are applicable in slow, heavy, common situations, high load situations, others are applicable in the fast enders spectrum and because generally speaking we talk about stretch shortening cycle most in the context of fast movements that's what we're going to focus on today. So as always I'll just whizz through the physiology and how this works and then I'll pass the ball over to Rob and we can start going backwards and forwards about the training programs and implications. So starting at the beginning, the stretch shortening cycle is the observation or the phenomenon whereby we see essentially an improvement in concentric phase performance as a result of having an eccentric phase directly before it. So we have this thing called the stretch shortening cycle effect and that essentially is the improvement in performance that we get in a concentric phase as a result of bolting on an eccentric phase beforehand. So if you do a concentric movement, concentric only movement, you'll find that you don't quite get the same bar speeds, you don't quite get the same jump heights, you don't get the same kind of force production as you would do or impulse production is probably a better characterization. You don't quite get the same levels of performance as you would do if you had a full stretch shortening cycle with both eccentric and concentric phases. So it's an observation or a phenomenon and the same way that fatigue is a kind of a phenomenon. Now, underpinning that, we can have any physiological mechanism that essentially enhances concentric phase performance whenever you've got an eccentric phase preceding it. Now, research is a found five separate mechanisms. I'm just going to pause very briefly and add a comment in here and say often in the kind of less technical parts of the fitness industry, you'll find people equating the stretch reflex with the stretch shortening cycle. So they'll say, "Oh, you know the stretch shortening cycle, all the stretch reflex." No, the stretch reflex is one of the five mechanisms that underpin or create the stretch shortening cycle. In other words, it is a mechanism of physiological mechanism that enhances concentric phase performance whenever you've got an eccentric phase directly preceding it. So essentially, we've got these five mechanisms, stretch reflex is one of them. Something called pre-activation is another. We've got the residual force enhancement effect and then we've got elastic energy storage in the tendon and finally, we've got an interaction between the muscle and the tendon that changes where on the force velocity relationship and muscle fibers are working. So, on these five mechanisms, so just very, very quickly, whisk through those, explain what they are and then explain to them. We're going to focus on for the purposes of high velocity movements. So the stretch reflex essentially is whenever the muscle spindles detect that the muscle is stretching, they will send the signal to the spinal cord, get a bounce back effect and the muscle increases its level of motility agreement. Now, this is obviously a way to increase muscle force and by increasing muscle activation and it's debatable, though, how much the effect actually adds to overall recruitment at high levels of effort. So what we tend to find, if we look at the kind of increment that you get, the extra recruitment that you get, tend to get a much bigger effect, much bigger increment on the recruitment at lower levels of effort than at higher levels of effort. So the stretch reflex is one of those things that probably enhances performance more so during long endurance running, that kind of activity, doesn't really tend to create much of an impact in the kind of high velocity high effort movements that we're interested in, like jumping throwing sprinting that kind of thing. So even though today a stretch wanting cycle, a mechanism, if you like, is probably not one that we need to worry about in the context of the high performance physiology that we're, you know, kind of devoting this podcast to the second mechanism is pre activation, that really just works all the time in the background, can't really change it very easily. Essentially, it's just that whenever you have any centric phase proceeding a concentric, you've already activated a muscle before time zero, which is the start of your concentric phase. So the muscle is already activated, it doesn't need to build any activation, build force production. It's already there doing that at time zero, so you get that extra benefit of impulse at the start of the concentric contraction. Again, I don't think this is particularly modifiable, like it just kind of happens most of the time that most situations will never, you've got a stretch shortening cycle going on. Thirdly, residual force enhancement effect. This is essentially where we're stretching Titan inside the muscle fibers in activated muscle fibers and then using to phase, if you stretch them in a passive stretch to get into a position where you're going to do a concentric phase, but without the centric activity phase before time, you don't get the same effect because Titan works differently in a passive muscle fiber from an activated muscle fiber. So the residual force enhancement effect essentially gives you a benefit to the extent that you've got a large number of activated muscle fibers or being stretched in that kind of eccentric phase. Now, for reasons of it to play in the moment, that works really, really well in heavy load situations, like powerlifting, not so much in the context of high velocity movements where we've got a lot of tendon movement backwards and forwards. So the fourth mechanism is elastic energy storage in the tendon. This basically is the first one that now is going to be interesting to us in the context of high velocity movements. Essentially, in this situation, the tendon is going to move around and stretch in the eccentric phase and then it's going to recoil and return that elastic energy to us in the form of kinetic energy to aid us in that concentric phase that we're going to do. So the more the tendon stretches in that scenario, the more elastic energy we get and the more kinetic energy we're going to be able to return to ourselves in that concentric phase to be able to enhance the movement that we're interested in doing. So you can see straight to way there that if the tendon moves around a lot, i.e. it behaves in a compliant way because basically if a tendon is stiff, it doesn't move around. I mean, that's the definition of stiffness. It bears repeating, but if you have a compliant, then obviously it will move around a lot in a little storm or energy. Now, the equation for the storage of elastic energy is a half kx squared, so k being the stiffness. So yes, if the tendon is stiff, but you do manage to stretch it and move it around a lot, then you will storm or elastic energy. But x squared x refers to displacement to the tendon, and of course being a squared term much more important. So much more important to have a tendon that does actually move around when you want it to, then have a really stiff tendon that doesn't move around a lot. Yes, the perfect scenario would have a stiff tendon that you can stretch a long way. That will storm much more energy than a compliant tendon that you can stretch a long way. But having a tendon that is stiff and therefore does not move around because you can't stretch it is not actually very good for storage and elastic energy in the context of high velocity situations that we're going to be talking about. And then finally, this idea of muscle and tendon interactions, if you have a muscle that is essentially capable of keeping a short length and allowing the tendon or pulling the tendon to a long length and letting that tendon then recoil, the muscle itself will stay at a shorter length because it's essentially forcing the tendon to do the lengthening and shortening instead of the muscle doing the lengthening and shortening in that kind of stretch running cycle movement. And as a result, the muscle then works closer to a constant length. And actually in sprinting, we actually talk about quasi-isometrics because I actually get to a point where they're really kind of just moving very slightly. And as a result, that able to produce really high forces because they're not essentially the fibers themselves are not shortening very quickly because you can keep the muscle to relatively short length. So it doesn't really lengthen and then have to shorten again, then obviously the shortening velocity of those muscle fibers is much, much reduced relative to the angular velocity of the body or the joint segments that you're actually rotating. So what we see there is the muscle is going to work much closer to the force and of the force velocity relationship. And as a result, lose a much high force. So both of these factors essentially, just like elastic and then storage, are relying on the tendon being compliant and moving to a long length and essentially then recoiling and giving us either in the case of the elastic and then storage, giving us that elastic energy back as kinetic energy or in the case of the muscle tendon interactions, allowing the muscle to shorten more slowly and therefore produce higher force. Now, the reason I said that these two mechanisms are essentially the ones we're interested in from a high velocity movement point of view is because what we see is that tendons tend to behave more in a kind of stretch and recoil type way. They behave in a more compliant way in those faster movements, whereas in heavy strengthening rooms like a powerlifting, they tend to behave much more stiffly and stay to fairly constant length. So you don't get a lot of elastic energy storage in that strength training exercise. You don't get a lot of keeping the muscle at constant length and the same kind of exercise. In contrast, in like a high velocity drop jump, you know, or a sprint, you will tend to see that the tendons are moving around a lot more and the muscle is moving around a lot less and therefore you do get these two sort of mechanisms operating whereby we're storing and releasing kinetic or elastic and then kinetic energy getting back and in the case of the muscle, we're allowing it to stay a parallel to the short ends. Now, that's how all these mechanisms are working. The final thing for me to say then before I hand over to Rob is just to explain exactly what it is that allows us to enhance the stretch shortening cycle with respect to these two final mechanisms. So again, what I'm explaining here only relates to these two mechanisms in which we're seeing a relationship between the muscle and the tendon And that's going to be much more applicable in high velocity situations. So what I'm not saying is this is how I would, you know, kind of see the mechanisms of improvement for something like the stretch running cycle in a powerlifting exercise, because that would be relying on the residual force and as much effect changing, not which would probably require something to do with Titan, whereas what we're describing here is much more to do with, you know, how do I make the tendon, you know, kind of stretching recoil to a greater extent? How do I keep the muscle, you know, to shorter length to a greater extent? That's kind of the adaption we're trying to drive. Now, hopefully, if you've been following along with this, you'll be thinking to yourself, well, this isn't an adaption. This is actually a ratio of effects. It's a ratio of muscle strength in the eccentric phase to tendon stiffness, because essentially what I'm talking about here, if I want to make the tendon behave in a more compliant way in a stretch running cycle movement, what I need to do is make the eccentric strength of a muscle bigger than the tendon stiffness. That's my adaption. It's not actually an adaption. It's the interaction between two adaptions. And that does not mean that I have to make a tendon more compliant. And it does not mean that I have to make tendon essentially changing anyway. What I have to do is make the eccentric strength of the muscle go up faster than the tendon stiffness is going up. And this is really, really important, because sometimes when I tell people that they've got things upside down and they don't want to increase tendon stiffness for the purposes of improving their planetary performance, they say, oh, so you're saying we need to reduce tendon stiffness and I'm like, no, I'm not saying that. I'm saying that you need to increase the strength of your eccentric strength of your muscle relative to your tendon stiffness. The very best plyometrics studies we've got to illustrate this point actually have tendon stiffness increasing during the experimental period of time when the people are training, but the eccentric strength of the muscle increases faster. And as a result, by the end of the training program, the muscle is pulling the tendon around to a great extent and it was at the beginning. Tendered actually got stiffer in those training programs very slowly, but that's not what we're interested in. What we're interested in is the ratio of these two improvements. So is my eccentric muscle strength increasing faster than my tendon stiffness or is it the other way around? And of course, that's in like, okay, well, now we know that what types of training are going to create those effects and the most kind of well described training method in the literature we have that does that is the plyometric activity. So plyometric kind of training methods are really, really good at increasing eccentric muscle strength while leaving tendon stiffness either largely the same or just increasing it very slightly. And I realize this is going to be kind of counterintuitive to many people who think that plyometrics work by increasing tendon stiffness. They actually don't, you know, in all the literature we've got eight to nine studies in the plyometric training methods at least the last time I checked probably more by now. And generally speaking, the increases in tendon stiffness are either non-significant in many cases or just significant and actually quite small. And in a couple of studies that have been done comparing heavy strength training increases in tendon stiffness with plyometric increases in tendon stiffness, heavy strength training or isometric training just blows plyometrics out the water in terms of increasing tendon stiffness. And again, we can go into exactly why that is in a future episode. But just for the purposes of today, plyometrics are not having any uniquely hugely beneficial effect on tenderness stiffness. They kind of leave it more or less the same increase it very slightly. And what they're really doing is kind of creating this eccentric strength increase over the muscle that is relative, you know, without really modifying tendon stiffness to the same extent. So that's the magic. That's the kind of physiology underneath the surface. Roll, tell us a little bit about how you're using plyometrics in your training programs at the time. Yeah. So I think just a backup a little bit. First, I'd actually like to go into what people should definitely not do. So Chris and I were talking just before we came on. And he just mentioned that a lot of people think that increasing tendon stiffness is what you need for improving your stretch shortening cycle. And it's an idea that you'll see all the time. I see it on social media. So people will be doing lots of isometrics, long duration isometrics have seen, you know, some mid-range split squat iso-holds, calf isometrics, all kinds of things like that. And people will say they're using it to improve the stretch shortening cycle. And like Chris just said, that is not really going to be the case. And we did mention using isometrics for increases or recruitment in that in the prior episodes. So we were just saying before we came on today, one of the things to clarify there would be programming wise, just making sure that you're not using too much of those. We mentioned very brief like three to five second contractions and really not using very many of them either. So you don't have to do very many, you don't have to do them super often since the adaptations are really going to dissipate very quickly either. Once you use them, you get those recruitment increases, those are going to hang around quite a while. So if you are using those in your programming for hip flexors, extensors, whatever it may be, just keep them brief and you don't have to do a ton of them, you know, just I usually just do one in a session, honestly. And then cap it there, just one max effort and then that's all I'm going to do. But you know, moving forward into like actual plyometrics that I tend to use, you know, I don't think it's going to be anything revolutionary here. I think a lot of people are looking for super special fancy exercises or like an even complicated sequences of exercises. But I'll just give some some basic ones that I use, you know, the first example from improving punching power and things like that. So some up providing plios. I mean, a big one, people have seen many times going to be plios pushups, really like those a little bit more of a drop plios pushup. So you get like a little bit more speed and definitely some more force requirements when you're actually like getting into that bottom and rebounding out of the bottom there. So I like those quite a bit into the same thing like a drop, Med Ball chest pass or a drop Med Ball throw really like those. And again, you don't have to do a ton of them usually I'm doing like three or four sets of just a couple reps. I'm honestly it's usually like some like three reps, never many reps at all. So keeping the volume on those pretty low terms of like some of the ones that I've liked some my syndrome overhead, you know, Med Ball slams and things like that. If you're watching like fighters and especially people on like the ground, they're throwing, you know, sometimes hammer fists in the ground and pound things like that. And they, you know, terribly clunky and slow. I've found those will help people beat, you know, just a little bit faster and more powerful with things like that. Help them not use just their arms and actually, you know, get more body into it and get more speed and power there. It's well guys I've worked with in the past, although honestly not I worked with a ton of baseball players, but just a few using things like, you know, emotional Med Ball throws and I would kind of a skip into that. So yet, a little bit faster velocity, more rotation and then just, you know, more output there. With all those, it is useful to be able to measure them. Obviously, you know, you want to be measuring them, see if people are improving, but at the same time, if you don't have a lot of equipment and stuff like that, as long as people are giving, you know, an absolute maximum effort and you can usually tell whether or not they are, you're still going to get the improvements there. It's really like all those in terms of lower body plyometric stuff. Again, you know, probably nothing revolutionary. You know, staying away from the calf things we mentioned with improving sprinting and all that stuff, probably not a good idea to be doing like calf eyes, those things like that. So really everything for the calves is super, super fast. Again, like the calf hops, we mentioned a bunch of times, really like those, you know, not too many in a set, just a few quality contractions getting as much highs as you can. Big fan of some like, you know, a lot of the more reflexive stuff. So you always want like that man and component. So something like a split squat, drop, drop, jump there, you know, you just take a feed off the ground, catch a rebound as quickly as you can, using very, very light loads, you know, with all these focus, I don't have a focus on any kind of like weight. People are using very light dumbbells, very light med balls, things like that. You could mention drop jumps, do use drop jumps a bit. So, you know, various heights there. And I don't know if you just mentioned it, but before we came on, Chris had mentioned that the concentric phase generally is not so, so important with these things all the time. So I'm not asking. That's probably, that's one of those things. I just asked people to think about what the adaption is that we're creating in the context of the stretch on the cycle. Because if our purpose is to enhance yeast and strength relative to the tendons stiffness, how is the concentric phase contributing to that adaption? It's not. It's like, I, I, people literally look at me as if, you know, I've grown an extra head at this point and say things like this, as I know, just think about what adaption would try to stimulate here. You know, it's got nothing to do with the concentric phase. No, so, yeah, cool. If we do the concentric phase happening, we can use that for another purpose, you know, for a speed development. And the core thing is that the straight shortening cycle effect does give us an enhanced speed in that concentric phase. So it will get you to our fast and velocity. Well, that's fantastic. That's going to potentially trigger some speed relates to those options. But that isn't more of chasing with the actual drill that we're doing. So it's like a side effect. It's a benefit. We can kind of take advantage of it. But it isn't necessarily the thing that we're actually training. So, you know, I think it's cool to do those things, but just kind of like, I'm always coming back to first principles and saying what is it about this particular exercise that I'm trying to derive? What benefit am I deriving from this drill or this exercise? And if it's an improvement in eccentric strength of the muscle relative to the tendon, then nothing in the concentric phase that I can possibly do will change that. So it's kind of like, but I do get the potential for that improvement in that in that speed related adaption. And that's really then what goes into them. I'm thinking about why if you are chasing those speed adaptions in that concentric phase, you know, does it make sense then to jump all through or whatever to the exercise for maximum performance? So typically in biometric circles, people will say, are they going to minimize ground contact time with this particular exercise? Or I'm going to maximize performance, jump height or whatever might be in this particular well, it's the maximizing jump high. or as to a movement performance, you're going to get the speed related to the adaptions. If you're minimizing ground contact time, you're probably not, because you're not going to get as big a kind of impulse in your constant face. You're not going to reach as high velocity as you're not going to trigger the adaptions in speed. I'm not entirely sure what people think they are triggering by minimizing ground contact times because every time I ask them, they give me this kind of reactive strength kind of lecture. What's the physiology? What's the physiology underpinning that? Tell me the physiological adaption that creates that outcome. I'm really not certain there is a clear answer to that. While on the surface, I can see the benefits of a maximum speed drop jump or a maximum speed plyometric performance to try and trigger those speed related adaptions. We did a podcast on exactly what those are. I'm not convinced that there is a reactive strength index or reactive strength outcome that you can underpin with a series of physiological adaptions that are unique to minimizing ground contact times. I don't see that that exists, but no, someone wants to argue that case. I'm happy to listen to that. I can't see it in the physiology of what it is. If they say to me, oh, well, it's rate coding because you're moving faster. I'm like, well, I can do that with a fast movement phase. I don't need to bring my contact times to get. The interesting thing is rate of force development and maximum speed physiologically are incredibly similar because all you're trying to do is build force faster. Well, that is a key component of maximum speed. So they're very, very difficult to disentangle, in my opinion. I think, you know, logically, I know we've got a history of, no, like you said earlier, we've got a history of thinking that tenderness differences driving plyometric forms through a history of all kinds of upside-down ideas. I think this is one of those upside-down ideas. I'm not convinced that minimizing ground contact times is the best use of plyometric. If you want to bolt on the maximum speed component of adaptions onto the actual stretch warning cycle component with options and get two things in one exercise. Anyway, that was, that was, that was, that was the second or the third thing I noticed while you were talking. The first thing I noticed was you were talking about the isometric stuff because I know we've been pushing isometric at a lot and saying to people, you can use these to maximize gains in recruitment. Two things occurred to me while you were saying that one was that absolutely. As you point out, you don't need to do lots of reps of these to get an increase in recruitment and because the reps and the total volume is really what's going to drive the tenderness difference adaption. If we just do one or two quality reps, I mean, personally, I can't do more than one max FI symmetric. My brain just shuts down. I'm just like, I know I can't do any more of these. Yeah, I mean, my, my second one is not going to be new. No, it's not. Absolutely. Not going anything out. I absolutely got a limiter in place. It's like, I do one of them and it's like, I'm done for the day. I'm not doing any more of those. But I think that there are, you know, kind of programs where people are doing a stack of them. Really, the only one that's going to trigger a recruitment gain is going to be the one with the max level of recruitment, which in many people's cases, I think is just going to be the first rep. So, you know, I know it sounds like not very much, but I think you're probably right that just doing those single repetitions is probably, you know, the best outcome for minimizing tennis difference increases while gaining the recruitment improvements. Yeah. And I think so many just said they're like, people always want to do like a big volume of like these things, a big volume of everything. And even a big huge, I see huge volumes of like biometrics, tough and programs. And they're in programs for, you know, really, really long periods of time and stuff like that. And I don't tend to use, you know, tons of plyo, certainly a tons of volume, or even them use them for very, very long. You and I discussed before, though, it's stretch shortening cycle tends to be kind of pretty quickly in athletes with your abilities with it. So you don't need to be doing a ton of them all the time. I mean, I much prefer to do more concentric based back speed stuff a lot of the time for more of the training time, the training year, and then, you know, do pliers. And that's tough to maximize stretch shortening cycle adaptations like for I guess more brief periods. You can attend to find at least people's tendons get beat up stuff like that. That's the thing a lot of people miss because generally we always have this kind of saying don't we in essence see that good essence see is the same thing as good injury prevention training. And the reality is it's not in this particular example because if you've got a tendon that moves around a lot, that's fantastic for stretch shortening cycle performance, but a tendon that moves around a lot is going to be a tendon that's more easy damage. And then that damage potentially could lead to a tendon opathy. So obviously we've got this kind of conflict between wanting the athlete to be as kind of capable as possible in terms of that performances, but also as resilient as possible. I think is that kind of conflict there that we've got to be aware of, not you say, just having periods of the year when we kind of allow the tendon to become more compliant for the purposes of maximizing performance for some competitions that are important. And then allowing it to kind of, or just, you know, kind of doing more heavy strength training and avoiding or semi-symmetrics, whatever, and letting it drift back to a stiffer state to avoid those problems, you know, around at time. I think it really just comes down to, you know, how you think tendon opathy is developing, obviously I'm not an expert in that area. So don't really kind of claim to have a model that scrubs it, but I think, you know, broadly speaking, from my understanding of the literature, generally it looks like, you know, if tendons are moving around a lot like ligaments, if they move around a lot, they tend to get damaged and therefore that damage could then be a problem. So yeah, I think it's definitely a balancing kind of effect. The thing I was thinking of when you mentioned the isometrics, just go back to that for a quick moment because I was suddenly realizing that when we look at periodization, and this is obviously something that we can talk about again in another episode, but when we look at periodization, one of the things that is hugely helpful in periodization, kind of programs, one of the reasons that people would argue for periodization over non-periodization is if you can do something early on in an athletic cycle that benefits you later on. And one of the only adaptions that actually does that is an increasing recruitment, because if you can trigger an increasing recruitment in your first couple of weeks of training, then you're kind of several weeks later, you're going to be reaping the rewards of that because you can now access more muscle fibers, you can produce more force, you can do more exciting, reach however lost is, there's all kinds of things you can do as a result of that adaption you triggered earlier on. So that actually fits really well if you're thinking in terms of building a base of recruitment early on in a periodized training program. That's simultaneously, it doesn't matter so much if your tendons are slightly stiffer as a result of doing those things, because when you've kind of done it, like you mentioned, you do those things earlier on, if you've done that, then you can then back off from them because the adaption, the recruitment adaption doesn't go away. Again, this is one of those brilliant illustrations of how if you think in terms of outcomes like strength and speed and power, then none of this makes any sense because people will say to me, I was building strength in the offseason. I'm like, no, you weren't. You were creating certain adaptions in the offseason, which may or may not stay with you if you stopped doing those types of training. You know, I had some questions in my Instagram literally yesterday where people were saying, well, we do heavy strength training for sprinters in the offseason and then we stop in season. Are you pulling my leg? I think I saw that and you said you would keep in, you know, a set of heavy hip thrusts and that stuff because, yeah, just make no sense to take it out. Any adaption, the neural adaptions you'll keep, but you could have got those mainly doing high velocity stuff if you wanted to or asymmetrics or bits and pieces there. Now, you don't need to have your strength training in order to create neural adaptions, you know, but the hypertrophy and the other peripheral stuff, you're going to lose that if you stop doing it. So it's like, we can't build strength in the offseason. We create increases in recruitment and hypertrophy and psychomyogenesis and all that good stuff. And then like, as I say repeatedly, if you turn you back on psychomyogenesis for five minutes, this is a peer. You have to kind of keep that stuff going throughout the kind of period of time in which it's supposed to benefit you. If you do like a whole chunk of three months off season training and, you know, however long the period might be in heavy strength training and then stop and month later it's like, well, you might as well not a bothered really. Yeah. You know, the recruitment stuff is going to stay. And I think that's just the point I was making. It's like, you get a recruitment stuff, it stays and then actually, if the tendon stiffness then goes back a little bit because you know, on the doing the isometric, you get the benefits of the recruitment, but you don't get the disadvantages of the tendon stiffness. That's just a thought process that I was going through. Well, I think, you know, one thing I've noticed too that where people will go wrong again, like offseason type programming is, you know, I guess a little unrelated to plyometrics, but I'll bring it back. So off season, you know, I still know a tons of people that'll go, you just said the high-perchrophy, heavy strength training route. One thing that I noticed people do a lot still is focus on slow tempos, slow e-centrics, all the extended e-centrics, all these things in the off season, thinking that it's going to build them more muscle, thinking it's going to do all these magical things. And then they don't move fast at all. You know, they don't not only do they not do any like plyo work or anything, they don't do any max speed work. And I think we said the same thing in the speed episode. So then if you do an off season four of five-second e-centrics on your squat bench, dem lift, and things like that, or even machine stuff, and then you all of a sudden go and try to just start chucking in plyometrics out of nowhere. Like, you've moved incredibly slow for a long time, and I see people do that a lot, and then they'll have an athlete go right into plyos because, oh, all of a sudden, now we're in fight camp, we're in going into the season for, you know, soccer for this, for that. And then all of a sudden, everything starts hurting. They feel beat up, they chuck in a big volume of plyos, and I'm like, you just move very slowly for six months. And now, you know, fuck up when you're going to move as quick as you can. I mean, really, if we're trying to simplify this down to the simplest level that I can then go off-season and in-season training programs shouldn't be that different really. You know, there are a couple of areas like we mentioned in terms of, you know, maybe isometrics a little bit more feasible in the off-season a bit less, you know, kind of emphasis on pliers in the off-season because you don't want the tendon to be moving around enormously potentially. So you can kind of argue that that is a subtlety there that as, you know, kind of emphasis. But realistically, we kind of say, well, you know, off-season, you could kind of get away with a little bit more volume, maybe a little bit more frequency. But really, the same stuff that is working in the off-season will work in in-season. It's just you might need to dial it right back to depending on the commitments of the athlete and what else they're doing. You know, if the athlete's hugely committed to a number of events and practices and whatever, you might have to dial the, like I said on my Instagram stories yesterday, I said, you could literally do a single set of hip thrusts twice a week, maybe a single set of hip legs. So have the hip legs will work twice a week, maybe a single rep of Nordics and a single rep of, you know, reverse Nordics twice a week. And that could be it. I mean, an unlike that will keep everything that you did in the off-season, you know, completely, you know, more or less intact throughout the end season without having to actually, you know, kind of create tons and tons of fatigue. Yeah, you'll never get tired. I don't expect of each of those. I don't think that people are going to get, you know, fatigue from doing single, you know, kind of sets of those heavy strengthing. So I was maybe a rep of Nordics and a rep of reverse Nordics twice a week or whatever it might be. So I think ultimately it's about, you know, it's not saying the two training programs and those two phases shouldn't be that different. It should just be that you're dialing back the kind of volumes and maybe the frequencies slightly as well in that period where you've got more commitments athletically. But there's something else I wanted to come back to that you said just to finish on perhaps you mentioned about tracking performances. And you also in a separate comment, you mentioned about the missed it now just for a little while. You say, we'll get it a second. We'll come back. No, it connected the two things together because you're mentioning the tracking of performances. I know what it was. You mentioned how the stretch warning cycle improves and plateau is relatively quickly. So you kind of get a period improvement. And really, what that represents physiologically, most likely in the context of high velocity movements is just the amount of compliance you get until you reach quasi isometric. Because when you get to a quasi isometric, you can't go any further. There's no outcome that you can kind of influence that will make the stretch warning cycle better. So if you think about it in those two terms, what you can do then if you combine those two observations and say, okay, well, I can monitor concentric phase performance and it's it's okay as a kind of a metric of stretch warning cycle, you know, to just use that. We can say, okay, so I'll measure the difference between my squat jump height and my drop jump height for height, not for ground contact time minimising. Look at the differences between those two. And I've got then a metric of what I would call my stretch warning cycle effect. So my drop jump height is 5% greater than my squat jump height. Very approximately, I know that that's an metric of my stretch warning cycle effect. Now it's not perfect. There's a number of other things going on there, but you know, it's good enough. If that improves over time while I'm doing the program that I'm doing, then I know that my tendons are moving around a bit more and I'm becoming more capable of generating those positive mechanisms that influence the stretch warning cycle effect in high velocity movements. It's getting worse, it means I'm kind of leaning heavy on strength training stuff and the ice images and it's kind of, you know, kind of now importantly, in both of those scenarios, jump heights could still be going up. You know, both jump heights could still be going up. One could just going up faster than the other. And that's the thing that I just keep going back to. It's like the stretch warning cycle is a ratio of things. It's not actually, you know, a thing on its own. It's the ratio of these things happening. So you can get squat jump height going up and drop jump height going up. This is one goes up faster than the other and you'll have an improvement in a stretch showing cycle or a reduction in your stretch warning cycle. It really just depends on which one is going up faster. And then literally you can just monitor that. As you're saying, just track and when it gets better and then starts to plateau, it's like, okay, we're done here. Yeah. And I think people always look for the fancy tracking, like all the data, but that's something that almost anyone can do in any gym. It's so easy. You use a phone app, you use like my jump, one of those, you know, anything like that. And you can just track it yourself, your coach can track it. Does not require fancy women. So that's, I mean, that's the stuff I really like is most people are not operating in fancy. But I get a lot of people coming to me saying, you know, I've got these motion capture kind of laboratory access and I can do all these weird stuff. And I'm like, they're hosting me a lot of that to get some really cool data that hasn't actually been regularly tracked. Because again, most people who are thinking about this stuff are not starting from the physiology and working away to the end of practical implication. They're starting from kind of, well, this is how things have been done. And this is how the outcomes work and we're building strength and getting, and I'm like, no, you're not going back to physiology and start building up break by break. And then you'll get to a point where you can see what actually should be happening. And then you come up with these observations like you're saying tracks to a very time. And you should see that the improvement or, you know, kind of gets worse rather than period depending on what you're actually doing. And you end up, and it honestly depends. I mean, like if you've just come off a period of competition, you actually might want it to get worse. So if you kind of, yeah, so like finished a competition. Yeah, finished competition season, you can carry on tracking, tracking, straight shore and cycle. And you should see that drop jump high relative to squat jump high gets worse because you cut down on the plyometrics, you improve at the increase the amount of heavy strength training and maybe isometrics you're doing. And you see a drop away from that really kind of effective straight shore and cycle in favor of a tandem that doesn't move around so much. Then you can then do other stuff and be a little bit more relaxed about the risks potentially involved in creating tendon damage. So, you know, actually, when you think about it, having that block of isometrics and heavy strength training immediately post competition season is actually a really interesting idea because it simultaneously puts you in a state to be able to do a little bit more volume. At the same time, it's actually priming you for equipment, you know, that will benefit you in subsequent phases. So in terms of periodization, it's actually an interesting physiological rationale going on. Yeah, for sure with that one. And I know we'll get into periodization because I've gotten some questions about it. We've got so many things to talk about. It's actually quite funny. I've just got a list and lists and lists of topics that we can cover. So, but that I think that hopefully is a good introduction to straight shore and cycle. In the context of fast movements, I think that's probably a good place to stop. Yeah, sure. So, thanks for joining me again, Rob. And thanks to our listeners for joining us both. And we will be here next week with another topic.