Reply to Coggan: There Is No "Quasi" Steady State.

A Complex System approach to the cuasi-steady state and FTP paradigm.

A few days ago, someone under the pseudonym Trev The Rev 5's shared my articles about the non-existence of a steady state and a critical power in a forum; and Andrew Coggan himself (or someone writing under his name) tried to contradict these ideas.

In these lines, I want to respond to that person, whether it's Coggan or not, and at the same time take the opportunity to reinforce some concepts I explained in the articles.

Andrew Coggan: "More #sportsscienceatitsfinest. It's only been known that the intensity-duration relationship isn't really hyperbolic (or, alternatively, that the work-duration relationship isn't truly linear) for almost 50 years. Use of a power law instead is just as old. I therefore question the authors' assertion that they have contributed significantly to any debate."

Here, Coggan mixes concepts. The fact that something is non-linear does not mean it can be modeled in just any way. A series of points with a non-linear distribution can be modeled using hyperbolic, potential, logarithmic, differential functions and more... Therefore, even if something is "non-linear," it is important to consider how it is modeled.

Although the first modelization of the power-time relationship as a powerlaw I am aware of dates back to 2009 (García Manso), it is very likely that someone had already tested it earlier without publishing it.

The fact that the function that best models the power-time relationship is a power law is not just "another nonlinear way of modeling performance." It significantly changes the entire previous discourse, as a power law, by definition, does not accelerate or decelerate its growth beyond a threshold. Therefore, its presence can only negate the existence of some sort of asymptote or threshold in the power-time relationship, which is the foundation of critical power/FTP.

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For the next point, I will group some of his responses to get an idea of what he is trying to convey.

Andrew Coggan: "‘Quasi.’ Really, a pretty dumb stance. Anyone with half a brain who has ever studied exercise physiology already understands that there is no such thing as an absolute metabolic steady state. As I point out to students, even resting metabolic rate can only be maintained for the duration of the human lifespan. Why is it that so many of these #sportsscienceatitsfinest articles originate from Spain?"

"You can lead a reverend to the truth, but you can't make him learn. As we have discussed ad nauseam, the 'threshold' aspect pertains to the physiological responses, which clearly change very rapidly over a narrow range of intensities. The mistake you are making again is conflating this fact with the shape of the intensity-duration relationship."

"To quote Ronald Reagan: 'There you go again.' Beyond the first few minutes of exercise, the slope of the intensity-duration relationship is quite shallow. Physiological responses, on the other hand, are markedly different when exercising at, say, 5% above the intensity corresponding to a (quasi) maximal metabolic steady state (sustainable for only 20 minutes) versus, say, 5% below (sustainable for ~2 hours). To reiterate, it is the non-linear nature of the physiological responses that leads to the concept of a 'threshold,' not the shape of the intensity-duration relationship. In other words, your entire post is a non-sequitur, revealing the weakness of your argument/thinking."

Unlike some, I will make the mental effort to explain Coggan's point of view before offering my response.

Maybe I am mistaken, but the central theme of his response seems to be that there exists a maximal quasi-steady state (MqSS) (whatever "quasi" might mean, but this "quasi" is the core of the argument), and that it has been observed that physiological responses to exercise differ if you work 5% below the MqSS (Maximal Quasi-Steady State).

Additionally, it is important to note that in Coggan's view, the MqSS and critical power (or mFTP) occur at practically the same intensity. This is reflected in his response when Trev The Rev 5 (by the way, I’d love to know who he is because it’s clear he knows a lot about this topic) shares an article stating that MLSS (Maximal Lactate Steady State) and CP are not equivalent:

Andrew Coggan: "You really should stop embarrassing yourself and your fellow citizens. Jones et al.'s focus on CP and whole-body VO2 kinetics is not only misplaced but self-contradictory. First, they define CP as the intensity at which ATP production is 'wholly aerobic,' then turn right around and claim it is higher than MLSS, even though that is biochemically impossible (at least conceptually). Then to make matters worse, Jones fails to even acknowledge that he (and Jamie Pringle) previously concluded that MLSS, not CP, represented the 'true' maximal metabolic steady state. It's okay for scientists to change their minds, but it's not okay to pretend that they haven’t done so, especially in a review as biased as the one you're quoting. It would just be sad, really, except for other questionable things that don't paint the Exeter group in a good light. #scienceisnotagame."

Fine. Starting from the premise that all this confusion could be resolved by simply stating that the maximal lactate quasi-steady state exactly coincides with the mFTP 😅,

to properly respond, we must demonstrate that there is no such thing as a "quasi-steady state."

Let’s assume that by "quasi-steady state," Coggan refers to some type of physiological change that makes us transition from a state of lower fatigue to one where we accumulate significantly more fatigue, damage, or something similar. It’s hard to imagine how we are supposed to understand this “quasi-steady state” when talking about fatigue, especially after observing that the rate at which we fatigue above or below this state is essentially the same… But let’s move forward.

The so-called maximal steady state is usually marked by the intensity at which the maximum amount of work can be sustained without blood lactate levels spiking. Increased blood lactate levels bring with them a host of systemic changes: metabolic acidosis, increased respiratory rate, heightened catecholamine levels, diffusion into other tissues, etc.

This threshold is REAL, of course, and highly important. The problem lies in the fact that it is based on only one parameter (lactate), which may be a somewhat reliable indicator of what’s happening metabolically; but fortunately or unfortunately we are more than that.

Each parameter we can measure behaves differently during an incremental test—not to mention during real-world efforts, where hysteresis appears, or the athlete’s goals and environment shift. Consequently, we could identify not one but hundreds of different steady states at the physiological level.

Here’s a graph I took from Jem Arnold’s X (formerly Twitter) account (a must-follow), based on Jamnick excellent paper.

In fact, we often think the intensity at which MLSS (maximal lactate steady state) occurs is special because only the data of physiological parameters that behave differently beyond this point are presented. If we consider other parameters, such as glycogen depletion and resynthesis, perceived effort, attentional focus, increased body temperature, or sympathetic nervous system activation, among others, we could not claim to be in a steady or quasi-steady state.

Moreover, inconsistencies in measuring MLSS within and between subjects already indicate that it is not as general or clear-cut as we might think. For example, the time a person can sustain their MLSS may vary by up to approximately 15%, and it also occurs at a significantly different intensity than VT2.

If we talk about a maximal steady state just because it is an intensity at which (under ideal conditions) lactate doesn’t spike, then perhaps we should say the steady state occurs at 40% of maximal aerobic power, as this is the highest intensity at which blood levels of adrenocorticotropic hormone and cortisol don’t rise, as found in this study.

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So, is there a physiological change beyond this MLSS?
Absolutely!
Of course, there is—but it doesn’t mean anything significant.

Although everything is interconnected, we must understand that the human body is not a machine that fatigues sequentially, but a complex system that self-organizes.

When we perform a task, such as cycling, the body tries to handle the stress with the lowest possible cost. At first, or if the pace is low, it does so by using the most efficient structures in synergy (slow-twitch fibers in the main muscles, aerobic metabolism, etc.). But as the pace increases, these previous synergies fail, and we need to recruit new physiological structures to sustain the task.

(Image showing how a network—a synergy—rebalances itself to sustain an activity even when some structures fail or are damaged. Something similar occurs in the body.)

To better understand, think about running a road marathon.

In the first few kilometers, when the stress is low, you are still primarily relying on aerobic metabolism, using the slowest fibers in the main muscles involved in running. The stress is low: you can talk, enjoy the scenery, and even joke around.

But as you maintain the pace, fatigue gradually forces the synergy between parts of the body to change. Fatigue in the slow fibers compels you to increasingly activate intermediate or fast fibers, raising your oxygen consumption and lactate levels. You start hyperventilating. Your running technique changes, you begin to land on your heels, and your stride becomes less efficient. Now, you don’t feel like talking or joking.

By the end of the marathon, your entire body is enslaved to the task (keeping the pace). To truly grasp how systemic this is, consider that you won’t even be able to focus on anything other than the effort itself. You can’t think about other things. Your running form has broken down, and now you compensate with muscles all over your body to maintain the pace. Oxygen consumption and heart rate continue to rise. Your entire body is adapting to ensure YOU can keep going.

¿¿Where is the steady state??

That threshold, that steady state (or “quasi-steady state”), is merely the marker we observe when the physiological network reconfigures itself. It tells us that up to this point (“threshold”), the previous synergies were capable of sustaining the activity, and beyond this, they are no longer sufficient.

And that point does not depend solely on intensity, as the critical power model imagines, but on the interaction between intensity, duration, the timing, how one reached that point (hysteresis), the environment (temperature, altitude), the individual’s goals, and interpersonal variability.

For instance, the first lactate threshold, the point where it starts to rise in the blood, only signifies that up to that point, the body did not need to rely significantly on acid-buffering systems or synergies to convert it back into glucose (liver), use it (brain, heart) or eliminate it (renal, respiratory systems, etc.).

Above the 2nd lactate threshold, the body can sustain very high-intensity exercise despite the acidity caused by lactate accumulation due to the "buffering" effect it can generate through respiration or the renal system, which can compensate for these acidity levels through changes in breathing and urine composition.

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One thing that unsettles me about Coggan’s response is that I didn’t expect it. He has generally emphasized the word FUNCTIONAL in FTP (Functional Threshold Power). I had the impression that for him, being useful was more important than being precise (something I agree with).

In fact, whenever I can, I quote his most famous phrase: “The best predictor of performance is performance itself.”

That’s why I don’t understand this turn toward defending CP or mFTP when he already had something better: FTP.

Because as a coach, at least FTP is clear and straightforward—no tricks, no gimmicks: how many watts you can sustain. That’s it. If you push more, it’s better than less. Forget about lactate, forget about estimations, forget about everything, and have something that works.

However, both CP and mFTP have the problem that, being models, they increase the margin of error and require more test.

In fact, now that we know there’s nothing magical about the 1-hour duration (nobody would think “FTP” must last 60 minutes if we used a calendar where days were divided into 10 hours instead of 24), why not use an indicator even closer to what we want to measure?

For example, FTP is not as functional as Coggan might like, since almost no one actually does a 1-hour test. Everyone does shorter tests, with the most common being the 20-minute test, from which a percentage (5-10%, depending on the person and coach) is subtracted.

This transformation of a 20-minute power (P20') into a theoretical 1-hour power (old FTP) already increases the margin of error, and then this theoretical 1-hour power is used to calculate training zones, some of which can be sustained for less than 20 minutes, such as Coggan’s Zone 5.

What sense does it make to do a 20-minute test to estimate what you could sustain for 1 hour, and then, based on what you think you can do in 1 hour, train with efforts you can only sustain for 4-5 minutes?

It would be better to simply perform a short test, such as 5 minutes, and train with percentages of that test directly. Remember: “The best predictor of performance is performance itself.” 😉

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To wrap up this episode, let me briefly address Coggan’s comment:
"Why is it that so many of these #sportsscienceatitsfinest articles originate from Spain?"

I agree with Coggan that the average level in Spain is lower than in most developed countries.

The average* level in Spain is lower because English proficiency is significantly lower. Very few people are capable of reading in English, and even fewer can speak or listen to it fluently.

As a result, general knowledge in Spain has been reduced to things that have been translated into Spanish.

And what has been translated?

Certainly not scientific papers. Nor the debates between sports scientists on Twitter or Wattage.

What has been translated are popular books. Those by Friel, Carmichael, Allen and Coggan.

I’ve always envied how, in English-speaking countries, people have already moved beyond concepts like TSS, CTL, FTPs… Meanwhile, I’ve spent over a decade explaining these concepts in Spanish, constantly battling the adoration for them, as they keep coming back. And when I question something, people say: “Coggan says it, the father of power-based training.”

Spain is the historical stronghold of Coggan and those who have continued his work. In Spain, books have been sold with slight edits to the famous “Training and Racing with a Power Meter.” Long academic and coaching careers has been made just translating Allen and Coggan´s ideas (without quoting them)...

It’s remarkable how important Coggan is here. At university, as a student, we were already using Coggan’s zones and the FTP test (or a 20-minute test to estimate it) to monitor performance—even though they weren’t scientifically validated.

*At the same time, there is a significant ammount of top-level scientists worldwide who are from Spain. I believe language can be a constraint that sometimes helps us grow even more. For instance, it exposes us to less information and, consequently, less noise. Since reading or translating English, especially a few years ago, was very slow and demanding, many of us have grown by translating only the most important scientific articles from English. This has allowed us to filter out the noise generated by social media and attention-seeking individuals, often leading us to have clearer ideas than those who are constantly exposed to broscience.

That’s why I’m pleased to respond to him. Above all, I hope this article is not seen as a “battle” or criticism, far from it. What Coggan has achieved in the world of training is incredible, and we owe him a lot for his contributions.

Everything he was able to achieve with the knowledge he had at the time is astonishing.

I simply believe that knowledge progresses—not because younger generations are smarter (in fact, it’s probably the opposite, given smartphones and social media), but because we stand on the shoulders of giants.

What took Coggan a decade to publish, I can read in a week. This allows us to read his work and many others’. From all these learnings, we can sometimes group them and create something new, like my book. A book that took me over a decade to learn and a year to write, and that someone will be able to read in a week and use to create something even better.

The passage of time for humans is linear, but the progression of knowledge is not. ;-)