Why you should - or shouldn't base training intensities on anaerobic threshold / FTP

0:00  So welcome everybody to this topic. We will have the presentation first, as always, and then some Q&A afterwards. Okay. So anaerobic threshold, or you could also say if you want FTP, we're not going into the weeds here with little differences or something, is obviously the most used metric, I think, to prescribing intensities when it comes to endurance training, all different kinds of sports. So I think the first thing that we want to do here is looking at what is it, what is anaerobic threshold, before we start looking at how or why we can use or maybe should not use it in which cases to prescribe training intensities.

0:49  Okay. So providing a little bit overview why it's even called a threshold and what is happening at intensities below or above thresholds. So on the left-hand side, you could say there is the intensities below anaerobic threshold, which basically means, and this was really the first also scientifically finding or definition, below anaerobic threshold, you find a stabilization in blood lactate levels, which is not the case above anaerobic thresholds. That is why you can call it the maximum lactate steady state, right? Furthermore, at intensities below anaerobic threshold, the pH level in the muscle will stabilize.

1:34  So basically pH as a marker for the acidity of the muscle. Those values will stabilize. However, above anaerobic threshold, as you can see, pH levels will decrease. Similar reactions are true for oxygen uptake. VO2 is stable at efforts below anaerobic threshold, at efforts above anaerobic threshold, as you may have heard about the slow component of VO2. VO2 keeps creeping up towards VO2 max. The opposite is true for creatine phosphate levels. So high phosphate levels in high energy phosphate level, creating phosphate in the muscle decreases, sorry, increases for the intensity.

2:25  Below threshold, it's stable. And for the intensity above threshold, it is slightly or constantly decreasing. And as most of you will be aware that in terms of fuel contribution, when you exercise, when your athlete exercises below anaerobic threshold, you can use or the athlete can utilize fatty acid as part of his energy source. However, above anaerobic threshold, fatty acids get, so to speak, pushed out of the metabolism, if you want to take it this way. So actually, fatty acid energy contribution is tending towards zero or is zero, okay?

3:07  Which means that below threshold, you can virtually go forever. Obviously, not true because of other factors coming into account. But above threshold, you will have a sooner or later pretty quick exhaustion, right? So, so far, what are we defining here as threshold, FTP, maximum lactate steady state whatsoever, okay?

3:32  In conventional performance testing setting, what you would see or how this would look like is that you can see here the metabolism in terms of the VO2 and VCO2 readings, so VO2 oxygen intake and CO2 output in red, oxygen intake in blue, in kind of a step test scenario on a, in this case, a bike ergometer where the power output is increased step by step, which you can see on this, on this green line where intensity is growing up. And then you can try to look at, so to speak, where at that intensity,

4:11  this kind of threshold values would lie, okay? That's kind of a classical approach, you know, step test in all different kinds of forms in the lab test or field test scenario. However, I wanted to bring up this slide firstly and mostly to show and make clear that what you can see here is that the oxygen uptake rises or increases almost linear with the power output up to, up to a level that kind of, up to intensity that kind of levels off, okay? And this is important because when we, when, when we want to understand the anaerobic threshold,

4:51  we also have to look at the aerobic metabolism because this is because of the lactate being, so to speak, the connector between the anaerobic or more precise glycolytic metabolism, where lactate is produced as a substrate. And this can then be used as a fuel or is used as a fuel in the aerobic metabolism. So you can see it here in a simplified way, you know, leaving out many, many steps here. Lactate versus pyruvate then goes into the aerobic metabolism, which is shown here as a circle, the TCA.

5:34  And so either lactate goes in or fatty acids go into this, into this aerobic metabolism as acetyl-CoA, okay? So long story short, most important thing only to remember here is that there's a connection, so to speak, well, well-known, well-established knowledge about the connection between glycolytic metabolism and aerobic metabolism and lactate being the main connector here, actually, okay? And this is important to keep in mind when we look at, when we look at anaerobic threshold. Because what we've seen in two slides before, when I showed you the readings from the metabolic heart, VO2 and VCO2,

6:16  you could see that in the blue line, the oxygen uptake increased more or less linear with power output, which means that, as we've seen in the previous slide here, if the oxygen metabolism takes up the lactate, then the aerobic metabolism is also marking, so to speak, the aerobic ceiling, the maximum capacity of the muscles to combust lactate. And this is what you see in the blue curve here. So again, if you can only combust lactate in the aerobic metabolism, which is something most people know because they do kind of easy exercise as a warm down or between intervals,

7:01  then the lactate combustion is limited by the oxygen uptake. Very simplified saying you cannot burn anything. If you want to burn lactate, you need oxygen. You cannot burn anything if you don't have any oxygen. And the lactate production is shown here as a red curve. So the lactate production kind of increases, not linear, but more curve linear or exponentially this intensity here described as power output, right? And because of these different kinetics, because of the different kinetics of lactate combustion and lactate production, there is an intensity at which basically the combustion equals the production.

7:49  And this is the highest intensity where you would see a lactate steady state, because above that intensity, obviously, lactate formation is higher than combustion or exceeds the possible combustion. And if the lactate or whenever the lactate production exceeds combustion, then the difference, so to speak, would have to accumulate. And therefore, you don't see any steady state lactate anymore. And therefore, this is, so to speak, the classic scientific explanation or definition of anaerobic threshold, if you want. Okay. So, so far, that should be all pretty clear. Now, what can you do to change threshold by training?

8:31  Or why do you actually see different threshold values, so different intensities, different running speeds, different power output, especially at different athletes or in different training status? So, what changes or what has to change if you want to change the power intensity at anaerobic threshold? You need to change the combustion of lactate or the production or both, right? Which you can see here in those dotted lines. In this case, in this dotted line case, so to speak, the ability to combust lactate is higher. And the production of lactate is decreased.

9:08  And therefore, this crossing point or, you know, point where combustion equals, combustion and production equal each other is happening at a higher intensity, higher power output, higher running speed. Okay. Okay.

9:26  And what is, I think, important to understand is that the regulation of what determines, what determines the combustion rate and what determines the production rate of lactate is the maximum capacity or the maximum ability to produce and combust lactate of each system, which is, in the case of the lactate, the maximum glycolytic energy production. And in case of the lactate combustion, the maximum aerobic energy production rate or energy turnover rate in the aerobic metabolism. So, you could simplify, call it two engines, a glycolytic anaerobic engine and an aerobic engine.

10:09  So, and that's nothing really new, scientifically speaking, right? There's tremendous amount of scientific studies you can find, you know, showing the actual ability of the muscles or the actual flux rate of, so to speak, lactate or pyruvate formation and oxidation. And just, here's just one where you can see this in a similar visualization because this changes in intensity, right? So, changes in intensity here written as percentages of VO2 max. So, you can see that at lower intensity, the actual pyruvate used here as a marker for glycolytic energy release instead of lactate.

10:55  So, pyruvate oxidation, you can see at a low intensity equals formation. And then, obviously, at very, very high intensity, the formation of pyruvate exceeds the possible oxidation tremendously, which is, yeah, so to speak, painting the same picture as we have just seen in this simplified graphs here of lactate production and combustion rates. Okay. So, again, this for understanding the scientific background, how anaerobic threshold is actually happening or why it's happening. And one of the more, you know, popular publications around this, you might want to look up if you're into the science here, is the work of Brooks, where similar statements can be found.

11:44  Again, just, I want to show you here that what I'm showing in this presentation is nothing that we kind of speak at Insight here came up with and thought it would be a cool concept. But no, this is actually grounded in literature where you can see, again, I marked the important parts in yellow here. Lactate oxidation is a linear function of VO2 up to approximate intensity of 75%, which is, as you may know, for most people around the intensity of anaerobic threshold, right? So, important to note, I think, or important for me to point out is that what we see here is really how, you know, how the lactate threshold or anaerobic threshold is created physiologically.

12:32  And that is something that is well-funded in science. So, after we kind of, you know, created a plain field here, everybody's on the same page on what anaerobic threshold is, I think it makes sense now to look at what is happening with anaerobic threshold in races in terms of how do we actually use anaerobic threshold? When do we raise that threshold? Because I think it's maybe the most common term, especially when it comes to coaches, but also athletes, especially with, let's say, recreational amateur athletes. You know, everybody has, you know, everybody has, have heard the term anaerobic threshold or FTP or whatsoever.

13:21  And everybody assumes, I would say, that it is a very, very important metric for their training in racing. So, therefore, before we talk about the training, let's look at, you know, how or when anaerobic threshold is actually important in racing. So, I want to look at sprinting. I want to look at longer efforts of a few minutes, up to like marathon running, and then also what's about a long time trial. Because especially if you come from the world of cycling, the most common thing is that you say, yeah, anaerobic threshold or FTP is your one hour kind of power output.

14:02  And because of the testing protocols have been out there using like 20 minute power output and then deducting some percentages or what. Because of that, I think the perception of many, many coaches and many, many athletes is that your 20 minute power or your one minute power, and therefore, obviously, everything in between is your anaerobic threshold or at least is very close to a threshold. Right. Okay. Okay. So, let's have a deeper look into these things as well. But let's first start with the sprinting. So, what you see here is data of, I think it was 2016, 2017, winning sprint in the Tour de France.

14:45  So, you can see the last, what is that, approximately one and a half minutes or something like that, 90 seconds, 60 seconds of the power output of the athlete before the actual sprint. Okay. You can see all these spikes here are obviously, you know, fighting for the position or keeping the position as well as accelerating after a corner. And then the sprint itself, the athlete peaks at approximately 1600 watts. Okay. So, what does that have to do with the threshold power? Well, I think it's pretty obvious that the efforts here before the actual sprint are significant above threshold value.

15:33  Right. We don't assume that the athlete has a threshold of 600 watts or something. Okay. And then the 1600 watts of maximum peak power here, actually. A part of that, and that, you know, might be a little bit unexpected here, a significant part of that is covered by aerobic metabolism. Because what is happening in all these spikes, all these peaks before and because of the high average power output, similar as we looked at, remember the couple of slides previously, when we looked at the VO2 values in the incremental test, right?

16:07  VO2 gets up this power output. So, when the athlete is riding for one minute, two minutes at an average power above 400 watts, this spikes up to 600, 700, 800 watts. This triggers, this triggers the VO2 going close to VO2 max. And with an approximately 80 kilogram athlete, this is approximately 500 watts. So, shouldn't be such a surprise that a significant portion of the sprinting energy is actually coming from the aerobic metabolism. And then, obviously, as, you know, might have been expected, a good portion of that energy is coming from creatine phosphate.

16:51  However, not as much as you may have expected. And the reason for that is not because the sprint is only 20 seconds or something. The reason is because the athlete has used a significant amount of creatine phosphate before the actual sprint to cover those changes in intensity. Because think about it, especially the aerobic metabolism is much too slow to cover these very, very short spikes of power output. And this is mostly done by breaking down creatine phosphate. And then the rest of the energy, the remaining part of the energy, is actually coming then from the glycolytic pathway.

17:34  Okay. So, dissecting the sprint performance here, what did we learn? There's nothing really directed, directly linked to this threshold power of the athlete. Right. It is too short. The intensity is, so the power profile is, so to speak, too stochastic. To have anything to do with, like, some almost steady state kind of threshold intensity. Right. There is no, there's no power that is even close to being steady state. And the actual sprint performance is not really linked, as you would have imagined, I guess, to anaerobic threshold value.

18:14  Okay. So, you say, well, no brainer. Could have skipped that, Sebastian, because it's a sprint. It's pretty obvious, maybe. Okay. How about other efforts? What you see here is critical speed curve or, yeah, so critical velocity curve, so to speak, of a speed skater, actually. Right. So, this is one athlete. Okay. And this is showing you his maximum calculated power output in speed skating on the y-axis. I choose that because most people come from a cycling background, so this will be familiar in terms of a power duration curve.

18:50  And these are, this is the time to exhaustion. And reading here the distances the athlete is going. So, same thing here, same story. When, let's say, as a maximum effort over two minutes with 450 watts, I think, similar to the sprint, what we just said, it should be pretty self-explanatory that there is, that this is above threshold. Right. This is not really threshold value. Maybe, maybe, this one here, this 60-minute effort is somewhere close to threshold. All the other efforts are most likely not, right, because they are most likely above threshold.

19:38  As you can tell from the power outputs, and as you can tell, especially from the asymptotic shape of the curve here, that, okay, if you accept that the asymptotic line here is somewhere, it would be somewhere at 300 watts or 280 or something, and this would be a threshold power, then, well, you can see automatically, inherently, that all the other efforts are obviously above threshold. Same thing for running. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing.

20:16  Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing.

21:02  Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. Same thing. The intensity is so high that lactate accumulates, that pH values decrease, that creatine phosphate decrease. You're not in this range with marathon running, obviously. Right? Marathon running takes at least normally two hours. And so the question here, the performance limiting factor is not really anaerobic threshold. It's a performance limiting factor is something else.

21:47  And one primary factor is glycogen or glucose availability. And glucose availability is not directly related or doesn't have any direct mechanical link, so to speak, to anaerobic threshold, as we will see in a later slide here. Okay? So there are some studies which link it, for example, to a percentage of VO2 max, but not really to a percent of anaerobic threshold. And if you would look around in professional Ironman races, for example, right, this is maybe even more an extreme environment compared to Marathon running because the efforts are even longer.

22:29  And then you will see that the threshold values of Ironman athletes are not necessarily the highest out there. And, you know, bike racer or some track and field athletes that have higher threshold values, maybe, compared to an Ironman. Because in Ironman and Marathon, it's about the fueling. It's about how you use fat and carbohydrates and not so much about the threshold value itself, really. But it's about what's happening below threshold. So long story short, before looking at 1500 meters, 5000 meters, 10,000 meters, we looked at intensity above threshold.

23:05  And now with Marathon or something, you're ending up looking at intensity actually below threshold. And there, because of the duration, fat and carbohydrate combustion rates are maybe more important than the threshold itself. And this is kind of known. I've seen this one from Aska's website here. I think most of you have seen it. So the fat oxidation rates can be vastly different in different athletes, right? The total is different and the shape of the fat combustion curve in different athletes is different and changes this training status, right?

23:43  And so this already goes into the topic here of how we use anaerobic threshold for training, maybe, instead of racing. But, you know, it already kind of implies a little bit that, well, the link from fat combustion rates to anaerobic threshold, there is a link. And we will come back to this later. So, you can see that here, but it's not a direct estimate or you cannot just compare. It's not absolutely proportional, so to speak. Okay. So what's about the classic one? What's about a long time trial?

24:18  I didn't have any data here for a 60-minute time trial. So I hope 50 minutes will do the trick here. Obviously, the differences in power output should be really, really small. So what's happening in a 50-minute time trial? And the point is, let's go back here to our concept on how an anaerobic threshold is happening, okay? So we have looked at this and we have looked at the combustion and the production of threshold, right? Of lactate, which then forms a threshold in this crossing point, which means that below this threshold,

25:00  similar to your warm down or recovery in between intervals, below threshold, the ability to combust lactate is higher than the lactate production. And above threshold, the actual lactate production is higher and therefore lactate would accumulate, right? So you can actually work these two areas, which are formed in between the blue and the red graph. You can actually work this into a different graph and just look at the ability, so to speak, to combust additional lactate, which you can see on the right graph, which you can see on the right graph as a gray curve.

25:37  And then the rate of lactate accumulation as the purple curve. And the touchdown here in between, so to speak, is a threshold, right? So again, the difference of combustion and production of lactate plotted in a separate graph here, so to speak. And what does this have to do with your actual effort? And we can use here the 50-minute time trial just as an example. You could use the same example for a 10K running or 70 points to your race maybe or whatsoever, okay? What we're trying to go here is that when we look at a power output,

26:18  and again, I had like this 50-minute effort here as an example. So this athlete in this particular race, he is riding at almost 500 watts for eight minutes, for the first eight minutes of a 50-minute time trial. And then he's riding at approximately 435 watts for the remaining 40 minutes. Obviously with some dips, right? So the green one is a power here. You can see that, you know, there are some section where power is lowered, maybe even for up to like two minutes, also here's one, but on average.

26:50  On average, it's more or less 435, and it's approximately 500 watts for the first eight minutes. So what does this tell us about riding at anaerobic threshold for like an hour, in this case 50 minutes? And why is this possible? How is this possible? Well, let's go back to the physiology here. So this threshold again, somewhere in the ballpark, 430, 440 watts, right? And let's assume, let's assume that the athlete is able to reach a maximum lactate concentration of 12 millimoles, right? This is his maximum capacity, so to speak, to reach lactate values.

27:30  And remember, those graphs here is plotted in millimoles per minute. So it's pretty similar. So if you're looking at the lactate concentration, what you can do now is you can, for example, look at 500 watts. At 500 watts, this lactate accumulation, as you can read from the purple curve, is approximately 1.4 millimoles per minute. And then you can just divide the 12 millimoles maximum by this 1.4 approximately. And you can see that the athlete would be able to write nine minutes at 500 watts until exhaustion. And as you might remember from the previous slide, he's writing actually eight minutes at 500 watts, right?

28:13  He could also instead write 14 minutes at 480 watts, right? This would, if you do the math here, 480 watts is approximately 0.8, 0.9 millimoles. So divide 12 by that and you get to 40 millimoles. Or you would be able to write 30 minutes at 460 watts. So think about this. Think about how this relates to a classic, so to speak, 20 minutes test to determine, you know, your threshold power. It's kind of a funny thing. If you ask most cyclists, they will tell you, yeah, 20 minutes is approximately my threshold power.

28:56  If you ask a 10K running coach, wherever various athletes are doing 10 kilometers in, let's say, 30 minutes, they understand that the athlete comes in with 10, 12, 14, 15, or whatever millimoles of lactate. And it's for sure significant above threshold. And that's kind of the same situation which we are having here. So this athlete having a threshold of approximately 330, 340 watts somewhere in this ballpark, sorry, 430, 440, has an ability to ride 20, 30 watts above threshold for 30 minutes, right? And he could also ride below threshold, let's say at 400 watts, and you can read he is combusting approximately 0.5 millimoles per minute, okay?

29:44  And the takeaway message and the story here is basically, even for a 50-minute time trial, the athlete is not riding at threshold all the time, maybe for some parts. But you should ask the question, why should he? If there is an ability to ride above threshold and go to 12 millimoles of lactate, or if you are more into powderation numbers, you could say, if he has a certain W prime, so to speak, which he can empty, why shouldn't he do that? Why should he do that? Of course he will do that.

30:15  And when he does that, at the beginning of the race, at the end, in between always a little bit, that depends on the pacing, on the tactics maybe, right? And this is the same thing the athlete has been doing here. For specific reasons of the pacing and how the race was set up, it made best sense for him to use, so to speak, his capacity to ride above threshold at the beginning of the race. And then more or less state at threshold for the rest of the race, but maybe, you know, dipping a little bit lower and, as we've seen before, recovering, you know, half a millimole of one millimole of lactate, which is also, by the way, happening between these two sections of eight minutes, 500 and 40 minutes, 435.

30:59  He has this dip where he's actually able to, you know, recover already from, let's say, 0.5 or whatever, millimoles of lactate-ish, right? So, 50-minute time trials, yes, the average power output is close to threshold and, therefore, threshold might be a good marker for the performance in this race. However, what's happening in the race, obviously, can be more or less slightly different. Okay, so how about training then? How about using anaerobic threshold to prescribe training intensities? After we've looked at, basically, how much it relates to performance in racing, which is rare.

31:41  There's actually almost no race where you sit exactly at threshold. You always sit above or below. And after talking about what threshold is, let's have a look at anaerobic threshold in training. And what is normally done in training? How, you know, how training is prescribed. If you look at most scientific studies about endurance training, adaptation endurance training, the standard is to prescribe the intensity as a percentage of VO2 max. That's the standard. And it's kind of weird or interesting that in a practical application, most people prescribe intensity as a function of anaerobic threshold or FTP.

32:27  And I would say maybe without thinking about it a lot, which is kind of funny because it's kind of common sense to prescribe training based on anaerobic threshold or FTP in practical application. And again, it's kind of common sense to prescribe it in a different way in the scientific world. And when you look at weight training, for example, strength training in the gym or something, then it's normally prescribed as a percentage of the one repetition maximum. And this is actually closer to prescribing training based on VO2 max, because the idea behind the one repetition maximum is to prescribe training as a percentage of the maximum ability.

33:11  You can, if you would like, maybe also say capacity of the maximum ability of the athlete, right? Have, have, have the training intensity described as a portion, as a proportion proportional to the maximum ability of the athlete. And that's the same vis-a-viso-viso-to-max. So the question we are looking to answer now is how does this relate to prescribing it as a percentage of, as a proportion of, of AT or FTP? Okay. And for this example, to do so, I've chosen, um, example of two athletes here of two cyclists.

33:48  Um, I choose cyclists because it's the most easiest way because we have the power output. If you're doing a running on swimming, you would have maybe to talk about economy. So energy cost of movement. It's not really a matter here when we have power output. So I have two athletes here, which are totally different athletes. It's more GC kind of guy with a pretty high VO2 max and a comparable low glycolytic, um, ability. So VLMX is 0.3, as you can see, and an anaerobic threshold of, um, of 375 Watts.

34:20  The other athlete is a sprinter. And what's this nice about this example is because he's heavier, even though he has a higher glycolytic ability, um, his threshold power is pretty much the same. And this makes it much easier now to compare the power values. Okay. So if you have high glycolytic athlete and the low glycolytic athlete, so to speak, right? Both high and VO2 max, not a big difference, just very, very slightly. This is the same threshold power. Okay. Okay. And what we are going to do with that example, we are looking at, at energy contribution at different interval settings.

34:59  We actually did a book about this and swimming last year, two years ago, um, looking at different interval settings here. Okay. And this is just, um, this is just, this slide is just showing you, showing you in general what we're doing here. So we, so we actually calculate the energy metabolism in a specific effort, and then we can look at the energy contribution and this kind of stuff. Okay. So let's start with that. Um, we are looking at the energy contribution of those athletes at, to start with, a four minute effort at anaerobic threshold, which is what you see on the left hand side.

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38:15  what we'll do now is let's see if we do these kind of exercises, let's see which percentage of the maximum glycolytic and maximum aerobic abilities of the athlete, so VL to max and VL A max, you want it this way, is actually used. So, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

39:06  so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

39:36  so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

40:06  so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

40:36  at least use a higher percentage of the VO2max and VLMx, but the differences are about the same, right? Significant different utilization of the VO2max and the sprinter and significant higher glycolytic and aerobic utilization of the systems in the GC rider. So, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

41:29  so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

41:59  at a lower percentage of VO2 max, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so,

42:29  so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

42:59  so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

43:29  so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

43:59  so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

44:29  so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so, so

44:59  the good message here is it's not three-fold different anymore. It's only two-fold. But still, still, still, still, still, the training stimulus the sprinter gets from this effort is tremendously lower on the glycolytic system. The training system is tremendously lower compared to the GC guy, low glycolytic athlete, right? So, maybe that's a trick. Maybe that's a trick to prescribe your aerobic efforts based on your, based on the one or four-minute power output. It gives you kind of comparable training stimulus. It doesn't really help with the glycolytic system, I guess.

45:45  And then how about sprint intervals? So, you can see the pattern here. Now we are looking at 10 times 12 seconds efforts with 48 seconds off. So, start every minute. And we have taken the intensity for the 12 seconds. Based on the 30 seconds maximum power output from the power duration curve. So, in this case, interesting part might be the stimulus on the aerobic system flips. So, now the stimulus first time on the aerobic system for the sprinter is higher, 70% versus 66, so 67-ish. And the gap, so the difference between the stimulus and the glycolytic system gets smaller.

46:27  That's the good news, right? So, I would say it's a little bit better, you know, getting a little bit closer. It's not really, it's not really, it's not really the same stimulus still, okay? How about going back to our marathon and Ironman guys? How about using the power duration curve, which we're talking about here at the moment? How about we're using this to have an idea about fuel combustion rates? What you see here, sorry, it's only in German. I didn't find something like this in English. So, let me talk you through here, walk you through a little bit.

47:07  So, what you see here is a coefficient of the correlation. So, correlating mean maximum power for 180 seconds, 300 seconds, 600 seconds, 1200 seconds, up to 3600 seconds. So, correlating the power output over those times to the FETMAX value, measured FETMAX and calculated FETMAX, so blue and orange curve. So, what you can see, obviously, as you might have expected, there's almost no correlation or a negative correlation between the FETMAX of the athlete and the power output for 30 seconds and 50 seconds. And then for the longer effort, 180 seconds, so three minutes, up to 3600 seconds, there is some kind of correlation between the FETMAX and the power output.

47:56  But you can see the correlation coefficient is maximum 0.7. So, there's a variation, you know, simplified saying there's a variation of 30%, which means, yes, there is a correlation between your threshold power, most likely, because there will be a correlation between your 3600 second power output and threshold. So, there is a correlation between the threshold, or there's also a correlation, what you can see here, between maximum power output for, you know, 20 minutes or 30 minutes and so on, up to an hour. There's a correlation to your FETMAX, but it's very weak, right?

48:35  So, it's a variation of 30%. So, this means, like, we should not argue about 10 watts higher or lower FTP if you want to use this for training intensity sub-FTP. Because if the variation, you know, if the variation is 30% and we're willing to accept that, then we should not argue about 10 watts higher or lower threshold power. So, some correlation, but pretty weak, 0.7, up to you to decide what you want to do with that. Long story short, I think, and that's maybe part of the takeaway message here, what we want to look at is to prescribe the intensity in a training effort in relation to the systems that we want to improve.

49:22  I'm using this example here from the weight training because in weight training, again, it's very, very much more straightforward. Nobody in a gym would come to the conclusion to prescribe the intensity, to prescribe the weight of the bar for a squatting exercise. Prescribe this based on the one repetition maximum of your Russian deadlift, right? Nobody would come to this conclusion. But that is bluntly saying what we are doing when we are prescribing, for example, intensities, as we have seen, based on an anaerobic threshold, the effect, the training stimulus on, for example, a VLA max can be anything, right?

50:08  It's not really linked. And I hope I can start, you know, to have people think about this a little bit, to have people think about, okay, which system do I want to train? And therefore, how do I prescribe the intensity for that? Because it should be the same system, right? And the example for this is prescribing the intensities for your training based, for example, the intensity to increase VO2 max to prescribe this as a percentage of VO2 max. So now we changed. Now we are prescribing the same 40-20 intervals for our Sprinter OGC rider.

50:52  We are prescribing this as a percentage, 110% of VO2 max. And because their weight is different and the VO2 max is slightly different, they're obviously getting tremendously different power outputs for the interval session. And now what's happening is that the stimulus on the aerobic system becomes very, very close. It becomes very, very close. I would say as close as it gets. And you have seen very similar numbers for the four-minute mean maximum power output, right? So four-minute mean maximum power output is a good predictor for, you know, exercise intensities for VO2 max, right?

51:34  Still, obviously, because our two athletes, our Sprinter OGC rider, have different VO2 max values. The stimulus on VO2 max is completely different, right? So this is one good way to do it. Again, could be the VO2 max, just as an example here. But really using the, so to speak, master metric, using the VO2 max, for example, in this case, to prescribe training intensities if the goal is to have VO2 max or your aerobic system adapt. So to put a short summary here, training intensities based on FTP, it's a good ballpark,

52:20  especially if you look at sub-anaerobic threshold training intensities, right? It's no direct conclusion to the fat or carbohydrate combustion, and therefore there's no conclusion to the fueling requirements. And the main problem is that because anaerobic threshold, and this is kind of the takeaway message here really, because the anaerobic threshold is created by the aerobic and anaerobic system, and just the threshold itself doesn't tell you how it is created or how it is formed, if you prescribe training intensity based on threshold, the stimulus you get for your glycolytic system,

52:57  especially for your aerobic system also, can be pretty much different. It will be vastly different, and it can be vastly different for different riders, or end for the same rider with different training status. Because if you change by training, if you change your VO2 max, if you change your VO2 max, then, for example, the threshold is not anymore 80% of VO2 max, but 85% or something. So if you prescribe training based on the same intensity in relation to anaerobic threshold, the actual effect of VO2 max or VO2 max will be much, much different, right?

53:34  And with that, I would like to open for discussions here, right? So there's the chat panel and the polls, and looking to see your question here. Thank you.