VO2 slow component and ramp test HR thresholds

My understanding is that due to the VO2 slow component it can take a long time to reach the steady state heart rate for a given intensity, especially above LT1, while above LT2 there is no steady state. Indeed there was reference in a recent podcast to it taking until the third set of the 5x5 threshold workouts until HR reaches ‘threshold’ (during the discussion re hard starts to such intervals), and I’m sure there’s lots of variability between athletes, and also day to day. That’s 15 minutes, admittedly with some short rests, but it seems it takes more than 5 minutes

So if that’s the case, how should we interpret the HR from a ramp based vo2 / metabolic cart (often 3 minute steps) or lactate test (often 4 minute steps)? To begin with I assume we should take final rather than average HR(?), but can we safely assume we’ve reached a steady state HR for such (relatively) short steps?

And is there a fitness / training experience aspect to it eg a fitter athlete will reach a steady state more quickly and have more accurate threshold HR, while a less fit athlete will take longer and have less accurate threshold HR? If so, that would suggest basing zones (even HR, which are often said to be more stable over time) off a one-off test is not a good idea for novice athletes?

Apologies if covered elsewhere but haven’t found it (also not in searching for studies)

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Great thinking @wescaine

The ramp test protocol is a generic protocol designed for cardiology. The application varies depending on weight, age, medical conditions etc.

You will get a nice indication of your Max HR, but:

  • shorter repeated power burst can push your HR higher
  • fatigue will keep it lower than max
  • testing after a base endurance block will give a low result
  • testing after a HIIT block will give you a high result.
  • nutrition (alcohol) will significantly influence the results
    If you want to know your Max HR to determine your traning zones, the indicative value of a ramp test is just fine.
    (especially when combined with your resting HR, to calculate Karvonen zones)

What you really kneed to know is:

  • at what HR value can i go for as long as i want with steady power output (your long ride HR, between 60% and 80% of HRmax)
  • at what HR value lies my lactate steady pace: (somewhere between 80-90% or max hr) → this is for race pace. You’ll feel this boundary when you’ve reached it, that slow down a tiny bit.
  • everything above is great for developing more strength

Having said that, you can also calculate your max from these percentages.

If you know how these three boundaries feel, HR values are just a bonus. In stressless steady live HR values are pretty accurate though.


Thanks for the insights. Hadn’t appreciated some of those variables.

Not sure I was fully clear in that I wasn’t talking just about max hr, but also the identified LT1 / VT1 and LT2 / VT2 HR from the typical step tests. They are taken based on lactate or ventilatory crossover points which occur at a given power step, and can see the power at those thresholds being meaningful. But is the HR also meaningful for everyone (especially if it’s an average, but even if final HR per step), given that the steps are so short… have we reached a steady HR actually? Or is e.g. LTHR actually higher (as it had further to drift up due to VO2 slow component) than that given as part of test results. Hope that makes sense?

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I guess @steveneal may have some statistics on that.

Great question. So the time it takes to reach nearly steady state will increase with increasing stage increments. At 4 minute stages, that’s going to be ~30-40w increments. Less than that, e.g., 2-3 minute increments is more like ~10-20w. I always tell athletes when I’m testing them that if they are primarily interested in sub-maximal capabilities, we should go with longer stage durations (4-5 minutes) so we can get better resolution and allow that steady state to be achieved. For athletes looking for maximal parameters (e.g., max HR), shorter is fine because we may not want/need as much resolution at the lower points (i.e., LT1/VT1).

You can even go as far as Dr. Inigo San Millan’s protocol wherein you move to 10 minute stages following the first three 5-minute stages and continue those throughout, taking samples every 5 minutes. Then you may see some very interesting changes within stages of the same intensity - that’s where you would likely see that drift occurring. And you can get a good sense for whether or not you actually achieved a steady state (with HR and lactate response). So yes, HR is also just as meaningful in my opinion.

To your original questions, I would agree on taking final, rather than average HR. Are you doing last minute, last 30 seconds, etc? In terms of fitness/training experience, there are differences, but when it comes to novice athletes I think it’s still worth prescribing zones based on HR, even with a one-off test. Just make sure they know that there may be changes that take place where they will need to re-test more frequently at first, or learn by analyzing their HR/power files how those changes would impact their zones.



Here are a few ideas I may be able to share.

  1. for the step test, take the last 15s average for heart rate and respiration. Graph the wattage for each step with the 15s average heart rate, and see if there is a deflection, this will be very close to your LTHR. Power on the X axis, HR on Y

  2. take max lactate after a step test, continuing after you have stopped each minute until it stops rising

  3. If you are trying to figure out where to start with intervals I might suggest you try the following.

You already have a step test result where you can take the peak 1m power for Maximal Aerobic Power.

Then do another test as follows.

30s ON at 90% of current Threshold.
15s OFF at 80w

keep repeating the above, adding 20w to each 30s ON, and keeping the OFF the same.

Continue the test to failure.

I have been having great success planning any intervals under 60s with the 30/15 test wattage, and anything over a minute with the peak 1m power from the step test.


Many thanks for each of your replies @kjeldbontenbal @ryan @steveneal - very useful as ever.

Seems that HR should reach a steady state in each ramp step, if the steps are long enough relative to the size of the wattage increase for each step. I’ve mostly been trying 25w steps for 3 minutes, and yes, taking some estimate of final HR (but not necessarily a systematic final 15s as suggested).

I guess further background to my question is I think I have a good sense of where my threshold is based on power (and know it can vary day to day), but actually different types of tests / efforts give very different heart rates, so LTHR is harder to pin down. And I can see the importance of getting that (near enough) right, to ensure quality execution of either threshold or tempo intervals i.e. that the right energy systems are targeted.

More specifically, with the ramp test protocol above, my HR around where I think threshold power is can vary from 165 to 172 or so (interestingly, with each test reaching the same final stage at failure ca. 10-20s into the 400w step, with max HR ranging from 184 to 193). (This kind of variability day to day is a reason I assume that to get the most of either lactate, ventilation or muscle oxygen monitoring, you probably need repeated tests or you own device?)

But the bigger question is how those HR compare to those from longer hard efforts, where I often sustain much higher heart rates for extended periods. I’ve tried variations of Joel Friel’s LTHR field test (or Kolie Moore’s protocol), and there I can average closer to 180bpm for the final 20m of a 30m test (with a lot of drift in that period… and I guess being ‘only’ 30 minutes it’s a bit above threshold)… some hard Zwift rides also average around 180bpm for the hour with power around threshold (though that’s admittedly also a bit less ‘steady state’ due to the efforts above threshold)… and some long hard outdoor climbs I also have an average HR of over 175 for more than 30 minutes (those are steadier and don’t necessarily feel ‘all out’). But at 180bpm in a ramp test I’m well and truly above threshold based on breathing and RPE.

I guess the ‘answer’ is that I rely heavily on anaerobic capacity in all of those longer (Friel test, Zwift, hard climb) efforts and so the resulting HR may not represent LTHR? I’m potentially better off using the lower HR from the ramp test in that case. I think though, that sticking to that lower HR will mean I won’t achieve the same power level for longer intervals (or repeated intervals such as 5x5), but guess that’s also OK to build aerobic capacity…?

Do you have the fit file for at least power and heart rate from your step test?

Nice to see that you are really thinking this through instead of just doing what ‘the internet says’.

Responding to:

I think I have a good sense of where my threshold is based on power (and know it can vary day to day), but actually different types of tests / efforts give very different heart rates

This is exactly why you should not focus on exact numbers, but ‘somewhere near xyz’ to guide your traning. Day to day variations will influence the test as much as it will influence your training numbers.
With the basic concepts of ‘extend or intensify’ and ‘go slow after going hard’, you are much better off. On the hard days you don’t need to know your threshold, because your goal is to go all-out or sub-max (you can stop your interval when your body indicates you reached threshold). On the slow days, you stay well below the threshold → must feel easy, but hard enough to not keep talking the entire time.
And don’t get me started on muscle recovery versus ‘cardio recovery’ and how this messes up the balance between power and hr you carefully calculated from your test :slight_smile:

It is all about listening to your body feedback, learning to listen, and learning to respect the signals. The data can really help to understand the signals.

I advise you to do a lot of structured training to learn how your body responds during and after the training.
For example: x minutes of zone y, assess restHR and muscle feel in the 2 days following the training.
Along the way you can do more complex self-diagnostics, as in: what is the effect of a LSD day followed by a hard day, and the other way around. And: how many hard days can i handle while maintaining given weekly volume.
By doing this you will learn how much load you can handle, and how hard vs light loads effect your body.

I’ve done this for about a year and concluded a few things, such as: with sub-maximal efforts i can produce more volume in a week than when including maximum efforts. In the end the volume has more impact on my performance than the max-effort training.
Such conclusions are more valuable than test results, as the test is not going to make you faster. Adaptive training and recovery are.

I personally never test…or put in a different way, every structured training is a test → by doing structured training with similar conditions (road, elevation, slope, etc) i can easily track my progress without the disruptions of testing. It also helps me to understand when more rest is needed, as my expected increase in performance is not happing at such a time. Where is normally does week by week.

I was happy to read that Nils vd Poel adopted the same strategy. At least it paid off for him :slight_smile:

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Thanks for the detailed response @kjeldbontenbal - always good to get another perspective.

I probably am taking a similar approach in that yes, I do listen closely to my body and recovery (including HR, HRV but see that as secondary to feel) to assess whether I have too much volume or intensity ramp happening. Over the winter I’ve actually been more in a maintenance phase, and am only just starting to increase volume and focus to build what I’d still consider base fitness.

Interesting that you say

as that sounds more like hard endurance (top of z2 in 5z model) or even tempo than ‘slow’. I can speak reasonably comfortably on a long slow day (but typically don’t!). Last year I may have done too much easy and not enough harder endurance, which is something I’ll experiment with this year.

Agree with you (as I guess most would) re: volume being key, and the need to continually have some challenge for your body (extend or intensify as you put it). The challenge is finding the best way to do that, which is also driven by your goals, time available, and also your starting point (training history, but also unique physiology - which is where you can get value from regular testing if committed to it). So also agree, there is no one answer for everyone.

It’s great to have the resources available on this site to help on that journey, including the various perspectives - even differences between the coaches on whether / when / how to include tempo or sweet spot in training, whether polarised is a must, or pyramidal is better… the common theme at least is the importance of building the aerobic engine, and there is clearly more than one way to do that

(Have also shared some data with Steve and will see what insights come of that)

Hi zone 2 might be high for a multiple hour ride, but you can always slowdown.

@wescaine hello, in the few tests I have looked at that you sent me, this is what I see in those few.

Below is a 3m step test looking at heart rate bins in icu (normally I would go 5 per bin but I can’t adjust that in ICU…

So from this one, in the 180 range for threshold.

Below from the 5m hr step test

I would pinpoint threshold at 170-175 heart rate.

If we then look at the Kolie moore protocol which I don’t really know much/anything about.

If I look at the last 2/3rds…we get the following average, right around 180

So based on what I have seen, I would say 170-180 heart rate is about threshold.

Is that really what you are looking for?

In your pwr step test, your heart rate and power are linear, which isn’t always the case. When I see this I need to use lactate, moxy or cart to find the threshold and it isn’t always indicated in hr deflection.

Hope this helps.

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Many thanks for the taking the time to look at this - much appreciated.

Definitely helps to know I’ve been interpreting the various tests correctly. And that you also see a wide range of potential LTHR from those depending on the approach i.e. anywhere from 170 to 180. (I had in mind, and have been using around 175 bpm actually).

I understand a lab test (lactate or metabolic cart) is needed to pinpoint it, but original question does remain open as to which measure is more meaningful for guiding training (specifically HR caps e.g. for 5x5 threshold intervals) i.e. is it:

  1. the (ending) HR corresponding to my threshold power from a step test (also with lactate or metabolic cart - the same ‘issue’ is present) OR
  2. the long term sustained HR from e.g. TT, noting the presence of drift

From my results, approach 1. is going to be 170 to 175 as you suggest (also referencing my HR at what I think my threshold power is in the ramp test), while 2. is around 180 (which for a step test is for sure above threshold power). If I know I can sustain close to 180bpm for extended periods should that be the cap? or the lower 175 HR?

For now I’m going to go with the lower estimate, partly as that’s a bit easier :blush: but also in the hope that as I build fitness I’ll see less drift and so lower average HR, even for long threshold efforts

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I would agree with the lower…

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What is the Kolie Moore’s protocol ? can you describe

He has a few but I’ve just done the ‘baseline’ one, which is

  • thorough warm-up
  • 10m at about 95% ‘target’ FTP
  • 15m at 100% ‘target’ FTP
  • then 10 to 15 min gradual increase to exhaustion

Average power over the whole test phase is meant to be the proxy for FTP, and you’ll have a TTE of around 35-40 minutes (his other protocols are longer). He uses that as 95% of a 20 min time trial has issues with estimating anaerobic contribution (it’s above threshold the whole time) , which is highly variable from person to person (though potentially with the 5 min blow-out effort before, as originally intended, it’s less of an issue)

If you google kolie moore ftp protocol you’ll easily find the others

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Here is the training peaks article:

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Haha The number of days my waking HRV is telling me I’m good to go but my legs are really disagreeing!