First Ventilatory Threshold and Fitness

Hi there, fellow Sufferlandrians

You know, I just listened to this podcast about cycling and performance and came up with the following questions:

  • Why is the aerobic threshold not typically taken into account when assessing fitness level/evolution?
  • Is it because its value is implicit or directly dependant on where our fitness level is at any given time (and characterised by other indicators such as VO2 max)?
  • If not, is it possible to improve the aerobic threshold alone while FTP, VO2 max or any other indicators remain fixed?
  • In such case, wouldn’t we be talking about being more efficient?
  • Isn‘t it desirable to be more efficient?
  • When and how train efficiency specifically?
  • Is it a good approach when our FTP and VO2 max are stuck?
  • How to measure aerobic threshold?

Sorry if I’m talking nonsense. I’m not expert at all in physiology but I’m always willing to learn about it.


It’s definitely not nonsense. But I’d guess the main reasons we don’t see it used are, 1 reliably measuring it in the field is difficult, and 2 IIRC it’s an open question whether VT1 and VT2 (for which FTP is proxy) really ever will move independently. And if they don’t l, testing FTP gets you everything you need and even if they do move independently to some extent, testing FTP still gets you a lot of what you’re looking for and you still have the challenge of measuring VT1.

Talking about efficiency, I assume you mean in the physics sense, which I think here means the amount of energy in that gets turned into work instead lost as heat. My understanding is that you get this by increasing your capillary and mitochondrial density through aerobic training. So any intensity of MAP on downward is doing the trick (although MAP works glycolitic systems too). Be patient and it’ll come. I would expect this to be reflected in both VT1 and FTP.

ETA, This is my take and I’m curious also to see what coaches think.

Also I do believe that you can get increases in fitness that are not reflected in FTP or maybe are, but are so subtle they’re indistinguishable from noise. This’ll be things like, what’s your max 5 min power AFTER doing 2500 kj of work.

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Very interesting answer, it made further reflect :slightly_smiling_face:

By efficiency I meant specifically developing a higher power at VT1 by means of physiological adaptations.

Best regards,

I’d say the reason it isn’t used is that the first ventilatory threshold requires measurement using equipment we don’t have at home.

I think a lot of people resort to using lactate levels instead of ventilation and even that is prohibitively expensive for most people.

It’s also really confusing on line. The easiest explanations to find are not what I learnt at university. I think it would confuse too many people even if it was possible.

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But that version of efficiency is the same thing, right? The energy is either turned into work or lost as heat, and research has shown that the smaller motor units with mostly slow twitch fibers are more efficient than larger motor units. You train these up, you get better efficiency in both senses.


On the TrainingPeaks podcast, Tadej Pogacar’s coach talked about measuring his aerobic threshold using lactate measurements. From what I understood, they took precise measurements of Pogacar’s Zone 2/3 boundary (which is unusually high to begin with) to enable him to train in Zone 2 more accurately and effectively. By pushing his Zone 2 power up even further, he could finish race stages very fresh compared to other riders.

I see no reason why you couldn’t do a similar evaluation on yourself. By closely observing your breathing you should be able to identify the power in watts where you cross the first ventilatory threshold. You’d just have to ride at a steady state for a few minutes at a time and keep increasing the ERG target power little by little until you notice the change.

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I think this is making things way too complicated.

To finish races relatively fresh compared to others, you can increase your FTP, and your time to exhaustion at FTP.

Then whatever pacing you need to do for the race will involve less fatigue. You will also be in a better position to engage in whatever tactics about FTP you need to use.

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It’s not all about FTP, though. Certainly, increasing your FTP will also move your aerobic threshold up. But from what I understand, they don’t entirely move in lockstep—the aerobic threshold is independently trainable to some degree. And if you can spend more time just below your aerobic threshold during a race, you’re going to be much fresher than if you had to ride in the tempo zone.


I am a little confused here.

You said: “And if you can spend more time just below your aerobic threshold during a race, you’re going to be much fresher than if you had to ride in the tempo zone.”

Isn’t just below aerobic threshold actually just below FTP, or even sweet spot, both of which are higher than tempo. Based on your initial comment I think you meant if you rode in Zone 2 because then you would be below tempo.

I agree with @devolikewhoa , I do not think the you can train the first ventilatory threshold independently of FTP because how would that map to your physiology?
While training improves capillary size, mitochondrial growth, and other similar capabilities, I do not believe lung size or function changes.

No, aerobic threshold is the top of Zone 2 endurance. It’s the highest power where you can primarily burn fats rather than carbohydrates, and before lactate levels start to really rise. FTP is the highest power you can hold where you have steady-state lactate levels (i.e. not rising exponentially), also known as your anaerobic threshold or lactic threshold (also VT2).

The 4DP test recognises that not all power zones move in perfect lockstep according to ratios based on average population values — people have different strengths and weaknesses at different power levels. The same logically applies to the VT1/aerobic threshold; some people (apparently including Pogacar) have unusually high aerobic thresholds relative to their FTP, which is why his coach had to base his Zone 2 targets on blood-lactate tests. It would be awesome if the 4DP also tested your aerobic threshold, but it would obviously be too difficult using power tests because it’s your ‘all day’ effort!

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No, the threshold being discussed here is much lower than where your FTP would be. It’s some times referred to as your all day pace in colloquial terms I believe.

When I had a lab test done they tracked both O2 and lactate and from memory, in terms of lactate it was taken as the first point at which there was any increase above your baseline. Whereas FTP (they didn’t actually use FTP at all but said it correlated) was the point at which lactate levels rise significantly and has a typical concentration, I “believe” it was something like 1.4mmol (no idea if I’ve gotten those unit even vaguely right!!)

I’ll dig out the report they gave me of the test and upload it if I can. Obviously the numbers will be meaningless, but it does have some explanations to go along with the physical readings so may be of interest.

Now, where did I save it…


Unfortunately it’s a pdf so I can’t upload it directly. Tried converting to a jpeg but it went all blurry. Hopefully the link above works

They use slightly different terminology as they were mostly relying on lactate for the economy test. They use Lactate Threshold for what is basically VT1 and Lactate Turn Point is what they measure in place of FTP.

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I’m super interested in this report!

As to where you saved it;
Finder → Sports → Aerobrain → Cycling → Testing

…otherwise you are a digital mess. :wink:

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Luckily it was in One Drive - Triathlon - Coaching Analysis - Loughborough so I clearly was organised at that point :slight_smile:

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I came across two interesting things relevant to this discussion. Firstly, this random blog post on TrainingPeaks actually recommends doing long aerobic threshold intervals right at the top end of your endurance heart rate zone (so, a distinct approach from just doing Zone 2 endurance rides). I don’t know how much science, if any, would back up this approach, and whether it would be more/less beneficial for increasing your aerobic threshold than training at or just below FTP. But it’s an interesting idea.

Secondly, there is some very recent academic research into using arcane-sounding features of HRV to estimate your aerobic threshold. In the context of their study, this HRV measure apparently has a very tight correlation with estimates based on gas measurements from respiration during exercise tests. If this finding holds up, it might be pretty cool, because it could allow apps like The Sufferfest to specifically identify your aerobic threshold, without anything other than a good heart rate monitor!


Wow, there is a lot of great, thoughtful, physiological discussion going on here!

I like the questions and thought process here, but I wonder if this might be thinking a bit too much into it? Taking a step back and thinking about the SUF approach to training, it’s basically polarized, where we program the most amount of training time in zone 2/aerobic/general endurance, and depending on the plan, what’s left is either high intensity intervals or tempo/threshold intervals to increase fitness and power at FTP, MAP, AC and NM. So if we’re actually adhering to our training plans and spending a lot of time in zone 2, which is our “all day” pace- my first thought is that this is not going to be the limiting factor for 99% of us when it comes to race day. I mean, if you can ride “all day” at this pace/effort, then how are intervals at this effort going to stress the body enough to produce an adaptation? I could see this being a good way for new/beginning cyclists or riders who’ve taken an extended time off the bike to increase their aerobic fitness as they get into the sport and structured training, but for riders who have been training for several years and already have enough aerobic fitness to ride 50-100 miles, I’m not convinced that intervals in zone 2 will be terribly effective, especially considering the amount of time these workouts take and the amount of training time most people have in a week. When it comes down to it, I think raising FTP and MAP will have more of a benefit for most people as those are the greater limiting factors when it comes to racing and performance.

*Remember this is coming from my coach brain, where I’m thinking about the most effective strategies for most people, rather than the small percentage of people who might benefit from implementing a technique that may or may not make a difference…If you have plenty of training time on your hands and want to give it a go, then I’d love to hear your thoughts and results. In order to do so, I’d make a plan using our building blocks in a linear periodization approach. Start with 2 base blocks- executing the first one at the intensities as prescribed, then in the second block add intervals of 5, 10, 15, 20 minutes at that high aerobic/low tempo zone of 75-80%of max HR, then moving on to the tempo, FTP and MAP blocks.
But also keep in mind that changing up your approach to training is usually enough in and of itself to stimulate some improvement in fitness. So whether you try this method or not, remember to take whatever results you get from it with a grain of salt!


This was something I read about in a book on run training where the author went into the different physiological pathways that different training methods use. He came to the same conclusion, that basically you get to a point where you maximise/reach diminishing returns on certain pathways which is why a change to training regime periodically can often be the best way to maintain progress. Forgive me though as I forgot all of the terms he used so that’s about all the detail I remember :slight_smile:


I now realize where the confusion came from. The distinction between lactate threshold and FTP is not universally agreed upon, nor consistently used. Andy Coggan originally defined them to be identical because for a majority of people it made zone testing easier.

The problem is that for many athletes they are not. That is precisely why a 20 minute power test for FTP is not an accurate measure for FTP:

Some people are relying on anaerobic processing even at 20 minutes which means they would never last an hour at that rate.


To provide some more detail, you have to train (among other things) your heart and circulatory system, increase mitochondrial density, train the nervous system (to deliver signals to the muscles to recruit them as needed), and the muscles themselves, as well as convert the muscles to the right mixture of types.

As you train the various systems, the bottleneck might move from one system to another. The bottleneck can move depending on what capabilities (sprinting, distance) you wish to train. So if you get to maximum mitochondrial density (whatever that would mean), to improve you may have to train your nervous system to be able to deliver the signals from the brain to move the muscles that now have increased capability.

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Kolie Moore also has an interesting podcast - Empirical Cycling. It has changed my mind on the validity and real world application of the main FTP testing protocol (Ramp/20min/8min). Interestingly I did a TTE test and I could hold my half monty FTP until 40minutes. My issue with suf plans are there doesnt seem to be any progression on moving TTE out. For example the FTP block, week 3 session is 5 x 8 - 40mins time in zone.

Anyone do any progressive sweet spot or FTP work with SUF to increase TTE?