Fast Physiology with Dr. Phil: FTP (Functional Threshold Power) Misconceptions

Summary
In this episode of Fast Physiology, Dr. Phil Batterson and Dave S discuss the concept of Functional Threshold Power (FTP) and its misconceptions. They explore different methods of measuring FTP and the importance of training at appropriate intensities. They also discuss the variability of FTP and the need for context in testing. Overall, FTP is seen as a range rather than a fixed number, and training strategies should focus on increasing time at or close to the second threshold.

Takeaways

• FTP is a field test that measures the highest power a rider can maintain in a quasi-steady state without fatiguing for around one hour.
• FTP is not a measurable physiological phenomenon, but rather a range of power output that represents the transition from sustainable to unsustainable physiology.
• Training strategies for increasing FTP can involve accumulating more time under or around the second threshold, depending on specific goals and race durations.
• FTP testing should be consistent and done in the same context to minimize variability and accurately track progress.

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Transcript

Dave S (00:00.878)
Welcome back to Training Babble. It is time for another fast physiology with Dr. Phil Batterson. Phil, thanks for coming back and doing this again.

Phil Batterson (00:09.119)
Oh yeah, of course Dave, this is so much fun. I love this sort of stuff.

Dave S (00:12.59)
Yeah, I'm having a lot of fun too. And if you have not been following, we've been doing a series going back and forth between Phil's podcast and Training Babble, doing a series of Fast Physiology where we pick a topic and then just kind of do a deep dive on it. Most of this has been born out of offline conversations over text and arguments. Yeah, yeah, exactly.

Phil Batterson (00:36.037)
Friendly arguments, we don't want to throw each other out of windows yet.

Dave S (00:40.814)
Yeah, exactly. So, so yeah, and you so you get to benefit from that. And so we did one recently on VO2 max and we kind of ended that show talking about VO2 max was not the best predictor performance that it was a prerequisite to be a high level athlete, but not the only thing. But it's really that percentage of VO2 max or your second threshold or FTP or critical power or whatever we want to call it is.

probably more important. And so today, we're gonna focus on functional threshold power or FTP and kind of misconceptions. And I think there are a lot of terms floating around or have been a lot of terms floating around to kind of define this idea, but they're all a little bit different. And so I think that's what we're gonna focus on today.

Phil Batterson (01:32.257)
Yeah, I think this is something that like you said gets thrown a lot around a lot without You know remembering what the true definition is or other things like that and from a physiological point of view right we kind of ended the last episode on view to max with view to max is a good prerequisite for performance, but it has to be used in conjunction with I Always say second threshold. I don't use functional threshold power and there's a reason for that

Dave S (01:59.214)
I've noticed that.

Phil Batterson (02:00.997)
along with economy. And what we're trying to do by determining our second threshold is we're trying to determine the point, the exercise intensity that elicits a change in our physiology from sustainable to unsustainable physiology. And this has been measured a number of different ways. Most common, lactate as something like Maximal Lactate Steady State.

or a lactate of 4 millimolar or a lactate of or the second inflection point in the lactate accumulation curve. It's also been used as second ventilatory threshold, which has a number of different ways of defining and describing that. It's also been used from NIRS, NIR -infrared spectroscopy as the second break point in the NIRS signal during exercise intensity tests that are ever increasing or the slope.

of the skeletal muscle oxygenation slope that goes from flat to negative. So I just wanted to make sure everybody was adequately confused before we dove into this topic. Because even for myself, as a researcher who I think has a little bit better grip on all of this sort of stuff, I still get confused with it because there's nuances to all the different definitions and all of that sort of stuff. So actually, Dave, if you wouldn't mind.

Dave S (03:11.534)
Yeah, exactly. Exactly.

Phil Batterson (03:29.309)
giving me a definition of what you use as FTP and potentially, you know, where maybe a misconception of what it actually is kind of comes into play.

Dave S (03:39.306)
Yeah, and so I think, and it's interesting, so I've always taken an interest in kind of the history of training, if that makes sense. And so I've been coaching since 2010 and started like studying training before that. And so I've kind of seen the evolution of it. And so with Phil Skiba and Andy Coggan and Joe Frill, and so I've seen as different books came out and they would come up with new terms and stuff like that. And so,

functional threshold power came about from Andy Coggan and Hunter Allen. And so I think most people are familiar with it or the most familiar with it from the book, Racing and Training with a Power Meter. And in there, the definition, FTP is the highest power that a rider can maintain in a quasi steady state without fatiguing for around one hour. And so with that, everybody wants black and white numbers. And so everybody said, oh,

FTP is what you can do for 60 minutes. It's your one hour power, but nobody wants to do a one hour test. And so they've come up with other ways to measure it. And so the most popular is probably doing a 20 minute time trial and taking 95 % of that, which gives you an approximation of it. And so, so I think that's one of the big things is that I think the thing that's interesting for me is that people try to equate or make them, um,

interchangeable that FTP is maximal lactate steady state. And FTP is not a measurable physiological phenomenon. It's just a field test. It's a power you can do for a pretty long time without blowing up. And so with that, I think, like I'm always thinking about this, it's like,

Phil Batterson (05:20.093)
Yes.

Phil Batterson (05:23.741)
Mm -hmm.

Mm -hmm. I like that definition the best.

Dave S (05:36.97)
I think the difference there, and I think where people can get a little bit confused, like if you were to go into a lab and have your FT, or have your, take different tests, you're probably gonna end up with a number lower than your 20 minute time trial, or the 95 % of your 20 minute time trial, because there's a big anaerobic component to that.

Phil Batterson (05:55.005)
Yeah, or higher, depending on what you're actually measuring because there's all of these second threshold estimations are all, when you line them up, they don't always happen in a sequential order, but there's always a range. And I think that's another thing people get confused about is that when we say like threshold, they're like, oh, that's like that number.

that specific time point in my exercise intensity, that is the actual tipping point. It's no, it's actually, it's probably a gray zone and it's probably, you know, depending on the person, it's probably anywhere from 10 watts wide to 50 watts wide, depending on the day, how fatigued you are, how hydrated you are, your nutrition status, all of those other sort of things. And it's again, the simplest answer is it's the,

Dave S (06:25.834)
Right.

Phil Batterson (06:52.032)
intensity that you go from sustainable to unsustainable. And even in that definition you read, they say a quasi steady state, because even at, even if you were riding for an hour, for example, if that was your FTP test, your body actually should not be in steady state. It's going to, you know, like if we're, if we're thinking about a steady or homeostasis or whatever it is, that would be everything is flat across the board in order to get to get through your one hour.

at exact exhaustion, which is like, you know, what, what that definition would be. You'd want everything to be slightly tilted down because then you're going to get, you know, like you want that start to be probably above and then the end is going to be below that second threshold, but you're going to actually get to the point of absolute fatigue when you hit that one hour mark. And that would be the optimal pacing strategy to actually like get there. But another thing that you said to me is that.

The 20 minute test actually when it was first prescribed had a five minute all out test beforehand.

Dave S (07:59.567)
Absolutely, yeah, and there's a paper too that talks about that they looked at the correlation between FTP as determined by the 20 -minute test and maximal lactate steady state as measured through lactate test. And if you included the five -minute blowout effort beforehand, so essentially a VO2 max effort beforehand, then the 95 % correlated pretty well.

if you didn't include the five minute blowout effort beforehand, then it was more like 92 % to kind of, and so essentially what that does is it adds a little bit of fatigue. And so it like, I think in one of our episodes, you talked about one of your advisors about how it's always the regression of the main and like, that's how I look at pacing and stuff like that too, right? If you go out too hard, like eventually your body's going to like, you're going to regress to that main and what's sustainable, you know? And so I think that's what that blowout effort does is that you,

kind of get rid of it, create some fatigue, and so you can only go so hard in that second 20 minute effort.

Phil Batterson (09:01.619)
Yep. And that was actually the idea behind the three minute all out critical power test was that you would go so hard in the beginning that you would accumulate all this fatigue and then you'd regress towards that maximal sustainable pace. But the problem with that was, is something was going on and I don't know the mechanisms behind that, but the average of the last 60 seconds, even if you are going all out was...

only still sustainable for about 20 minutes or 30 minutes if you were like really, really good. Um, but I tried that test. I tried, I tried that during my master's degree and we had like a whole class that tried it and like, it was a fricking brutal man. Like we'd be like, okay, three minute test average of 60 minutes or yeah, the 60 seconds at the end, we'd all be like, okay, 280 to 300. And then we just set like an ergometer and just be, it would be almost at 300.

Dave S (09:35.973)
Yeah.

Phil Batterson (09:56.755)
And I think like it was it was fricking rough. It was bad.

Dave S (10:01.408)
Yeah, I've done it once and it was, it's pretty miserable because there's no pacing at all. It's just, it's literally all out. The goal is to blow up. Yeah. So, so getting back to FTP and some of the misconceptions here, you just touched on something and this is probably one of my big soap boxes is that people want it to be a very defined number. Like it's two 63 and it's really not. And like I've in.

Phil Batterson (10:07.059)
Yes. Yep. Yep.

Dave S (10:30.752)
after talking with you more, it's like I've started to come to call these things transition points instead of thresholds because thresholds gives this idea that it's very like black and white, like under it it's this and over it it's that and it's really not. So I like this idea of like transition point, like as you approach it things start to change and like as you go over it like really just starts to change. And so like you just said, it's like a lot of times it's, I guess we'll go back to like, even if you're getting things measured in a lab,

it's open to interpretation of the lab assistant or the doctor that's doing it or whatever, right? And so it's usually within like 10 to 20 watts, you know? And so, yeah, it's like really don't get so hung up on my FTP is this, it's really a range. Think of it as like plus minus 10 watts.

Phil Batterson (11:18.353)
Yep. Yep. Yep. Yeah. Even depending on, you know, what, what number you're actually using, right? Cause if you're using, uh, that, that three minute critical power, right. You know, then, you know, maybe, maybe that, I don't know if there's like a 95 % correction thing to get it out to the hour. Also like an hour is such an arbitrary number because who, are there any races right now? Like, is there like an hour like crit race or something like that? That would be.

Dave S (11:47.546)
knows. So why he came up with that is that a 40k time trial would be around an hour for a lot of people, or that would be their goal. If they could do 25 miles in an hour, then they're averaging 25 miles an hour. And so, but since like 2014,

Phil Batterson (11:51.953)
Mm. Okay.

Phil Batterson (11:56.945)
Okay.

Dave S (12:05.428)
and we were talking about this offline. So Andy's been very adamant that I never set an hour, he said around an hour, and that when they put it in the book the editors changed things or whatever, but I went back and looked at his original 2001 paper where he first described the ideas and came up with zones and stuff, but in that he did say about an hour. So anyway. But since then, since 2014, it's been...

Phil Batterson (12:30.385)
Yeah.

Dave S (12:35.456)
kind of amended where it's like 30 to 70 minutes depending like for most athletes in my experience it's like 30 to 40 minutes right but but you can get these diesels we like on our last episode talking about vo2 max and if your vo2 max and your ftp are very close it's like yeah they can probably hold it for like 60 70 minutes because they just don't you know like they don't have a lot of that top end and so that might be something to work on and so yeah so anyway

Phil Batterson (12:39.729)
Yeah.

Dave S (13:03.931)
That would be our next misconception is that it's not an hour. It's around an hour for most people. It's probably 30 to 40 minutes.

Phil Batterson (13:11.985)
Yeah. And again, it's like, so, so the whole idea of figuring out where, you know, transition zones are or points of interest are, is to be able to then train very specifically to raise that transition area. Right. And, you know, in terms of like, from a physiological point of view, right, we want to be able to...

maintain aerobic homeostasis longer because again, we're able to then spare muscle glycogen a little bit better. We're able to avoid the accumulation of protons and inorganic phosphates, which are positively and negatively charged particles that can then interact with other things in the muscle and then cause fatigue. It's not lactate and that's a, that's a topic for another day. Um,

But it also then gives us better lactate handling too. So you'd see less accumulation of say lactate into the blood. It means that your, your mitochondria are actually better at uptaking that lactate and using it to create energy aerobically, as opposed to transitioning to more non -aerobic or anaerobic sources. So that's, that's the idea of estimating this second threshold, because like I just, the point that I was just trying to make with like who's actually racing an hour, not many people.

And so most people, so, but there is still importance to determining this because it helps to again, develop the system to be more fatigue resistant.

Dave S (14:49.302)
And I guess just to give it another kind of descriptor or name, I guess I like, I always think of it as a point at which you start to redline. And I think it's really important for athletes to know that and like experienced athletes can really feel like, you know, when you're approaching it and you get to that point, you're like, okay, this sucks, but I can do it for, I can do this. You go a little bit harder and you're like, Nope, I'm going to blow up. And so you have to back it off. And so like getting a point and like you said, it can change day to day, week to week.

Phil Batterson (15:12.525)
Yep. Yep.

Dave S (15:19.094)
within the week, what have you. And so, right. Yeah, exactly. Right, and I like, yeah, and so I was sick for three weeks and barely rode my bike and my FTP dropped pretty significantly and it's just now starting to come back up after training consistently. And so I guess that will bring me in my maybe third and final point about this is I think FTP is worn as like a badge of.

Phil Batterson (15:20.877)
whether you've been sick or not, right, Dave? That was something that we've learned recently.

Dave S (15:47.958)
I don't want to say courage, but it's very much like an ego thing. Like everybody wants the highest FTP possible. And it's like really like, it's less about that and more about like training at appropriate intensities. And that's what matters most. And so if you did do a 20 minute test and took 95 % and you're trying to do FTP intervals, like four times 10 minutes, and you're only getting through one or two of them, it's like, it's probably an issue. If we're talking about an intensity that you should be able to maintain for 30 to 60 minutes.

and you can't do 10 minute bouts of it, like it's probably set too high. And so my question to you, Phil, when we're talking about increasing that second threshold, is it better to train a little bit below it? Is it better to train a little bit over it? Or should we do a mix of it?

Phil Batterson (16:21.896)
Yes.

Phil Batterson (16:36.49)
This is, I think, all of these questions are great. So I think two sides of it. If your goal is to accumulate time at or close to second threshold, and your goal is to accumulate more time than you would if you just did, you know, like an FTP or something like that, then you would want to be under it slightly.

because then you'll be able to accumulate more time very close to that threshold. If on the flip side of things, if your goal is to accumulate the most stress kind of around that transition area, then you're going to want to go a little bit higher, shorten the reps, shorten the rest, and then accumulate volume from that perspective. So there's multiple ways of going at this.

And I think at the end of the day, it kind of depends where you are in terms of, um, you know, the specificity of the race season, where you are in terms of, um, you know, what race you're actually doing. If you are somebody who is racing between 60 and, you know, maybe 70 and 90 minutes, then you're absolutely going to want to accumulate more time under that under threshold and time under that tension, right?

And you know, so again, you're and most likely what's happening actually during your workout is that your threshold is changing to the point where you went from in the beginning you're you're exercising Easier than your second threshold and then at the end you're actually exercising higher than your second threshold if you're accumulating enough volume so that I'm just trying to add more and more confusion like I said, you know in order in this whole topic because

Dave S (18:18.612)
Right.

Phil Batterson (18:27.627)
It is complicated, but again, I think it's proximity to, you know, your actual adaptations that you want to try to get. So, you know, whether you're plus minus, there's benefits to each, but as long as you're close and you're accumulating more volume around that, and because that's what you're trying to push up, then you're most likely going to have the most luck pushing that up at that point.

Dave S (18:51.602)
All right, so what are your takeaways for FTP for everybody?

Phil Batterson (18:56.915)
Um, so, so I gave a bunch of different definitions and all, and all of those sorts of things. But I think what I, what I almost always come back to is pick a way to measure and evaluate your FTP or your second threshold and repeat that. Don't, don't go from a 20 minute FTP to a 45 minute FTP to an hour FTP to critical power to three minute critical power to four millimole lactate. Pick one.

use that as your driving metric for your second threshold and see if it's actually changing over time. Because you can't compare, like you can try to compare these different metrics, but you're going to eliminate more of the error within those measurements by doing the same thing with the same protocol over and over and over.

Dave S (19:44.847)
Yeah, and I would just add to that also in the same context or same environment. And so, so you don't want to, I mean, in my experience, like power meters, even their stated accuracy is like plus minus 2%. And so even if you had the exact same power meter on all your bikes and indoor and outdoor and everything else, there can still be variability, but most people don't have the same power meter. So you've got different brands, different manufacturers. You've got the trainer on the smart trainer or the power meter on the start trainer and all these other things. And so.

Phil Batterson (19:48.937)
Yes. Yes.

Dave S (20:14.447)
You don't want to do a test inside one week and then four weeks later do it outside and like try comparing those two because it could be wildly different. So yeah, I think context matters as well.

Phil Batterson (20:26.44)
Yep. What's your big takeaway?

Dave S (20:28.207)
I think my big takeaway is that it's just...

metric. It's not the metric. And so it's just one more thing that we're trying to measure in terms of like VO2 max and aerobic threshold or whatever we want to call it like top of zone two things like that. And so it's important but it's not the only thing that matters and it's not written in stone. So if we were to test like three different weeks we'd probably get three different results. And so

Phil Batterson (20:37.352)
Mm -hmm. Mm -hmm.

Phil Batterson (21:02.12)
or three different days in a row. Yeah.

Dave S (21:03.629)
Right, exactly. And so it's like a snapshot in time just to help us like hone in on intensities and make sure we're doing what we think we're doing.

Phil Batterson (21:12.904)
Yep, agree with you on that one.

Dave S (21:15.533)
Awesome, so where can people find you?

Phil Batterson (21:17.992)
Yeah, so you guys can, if you have any questions or anything like that, Instagram's the best place to reach me. I'm at Critical02. And then if you want to listen to more long form stuff, catch up on other episodes of Fast Physiology with Dave and I. You can listen to the Critical Oxygen podcast. That's on YouTube, Apple, Spotify, pretty much wherever you could think about listening to podcasts and stuff like that.

Dave S (21:42.349)
Fantastic. Thanks again. Looking forward to the next one.

Phil Batterson (21:46.248)
Awesome, thanks Dave.