Raising the Ceiling (FTP/VO2)

Hi all,

Long time listener to the podcast, have learned a great deal so thanks for all the info you put out.

I’ve been training for a few years now, and have essentially been plateaued around the 315-330w FTP (consistently ~3.9wkg) for about 3 years, and despite increasing mileage and CTL I’ve not really moved this upwards. In races, the place I always struggle is the 3-8 minute efforts (generally climbs, however I think this is just because that’s when this kind of effort occurs). My peak 5-6 minute power is ~400w (so FTP is ~80% of this) and it’s recently been suggested to me that I’ve almost maxed out my FTP as a percentage of “VO2”, and therefore need to create headroom. My anaerobic and neuromuscular power is pretty good, it’s once I get past the 1-2 minute range that the problems surface.

I sort of guessed at this last winter and during the spring I hit a fairly big 12-15 week block of polarised to try and target this, however the results I saw were limited. I’ve since done a fairly big block of base/threshold work over the winter and thinking now could be the time to target my weakness again with racing looking doubtful.

I guess this prompts 4 questions for me and I’m interested to see what the thoughts are…

  1. What are the best ways to target this, max efforts once a week building the time in zone and raw power, over say, 2 blocks of 3 weeks with a recovery week in the middle?

  2. Will 2 blocks be enough to actually trigger measurable physiological adaptions/improvements?

  3. I find 4-5 minute blocks of upper Coggan Z5 difficult to complete repeatedly, but 30-15s and 30-30s at the top of Z5 much more achievable. Is this because I’m compensating with my anaerobic pathways and therefore not really hitting my VO2 properly?

  4. Is it a matter of just doing the longer ones and sucking it up as that’s where the improvements live?

Keen to hear what the much more experienced heads in here think!

Thanks in advance,


Hi @stuarthardy, and welcome to the forum! Thanks for your post!

Great questions in there, and I think a common struggle for many of us. It’s good that you went through a block already to see what kind of results were produced when you train that limiter. The fact that you did not see much in terms of performance improvement from it may suggest an alternative approach. So maybe you can fill us in with your approach in the 12-15 week polarized training that you went through.

One thing I will suggest initially is that ~80% of max, you still may actually have some room to go, so it may be that you can also target your threshold to continue a push toward that ceiling. The potential is there to achieve upwards of mid to upper 80%.

To your questions:

  1. I look at overloading that system in terms of essentially time under tension, or time at intensity, however you want to think about it. So we want an overload - 85-90% of maximum HR is sufficiently hard to trigger those central and peripheral improvements to boost VO2 max. I look at the sessions as the amount of time spent at or above that level. Initially I might target 15 minutes, and work up to 20-25 minutes. While power will change, I focus more on finding the terrain (virtual or real life) that will support a consistent high power output so we can maximize that HR response around that range of 85-90% of maximum.

  2. 2 blocks of 3 weeks would be sufficient with some rest in between. You could start that way initially, aiming for 2x per week with those workouts being your key sessions for the week. Depending on your level of development, you could get away with a 3rd session, but I normally don’t recommend that for most people. You could also block up these workouts, but have to focus heavily on the recovery as well. I would not recommend that as a starting point, but know that it’s out there.

  3. I can feel your pain (literally!) on the Zone 5 intervals being difficult to complete. These are VERY stressful intervals. We can dig into a lot on the details of how you approach them, your pacing, preparation, and recovery from them. But in general, this is why I maintain a focus on the HR response and not strictly a power number. Dial into the power range, but let HR be your guide. In addition, moving into efforts like you suggested (30/15 and 30/30) are good options. I would encourage you to check out Dr. Seiler’s video on Short Stacks where he discusses work to rest ratios. Greater than 2:1 is where you can start to get enough of a load to achieve a load close to VO2 max.

Here’s an example from a recent “Ronnestad” workout where I did 3 sets of 13x30/15 and ended up with a total of 30 minutes spent at 85% or greater of maximum HR. So those can be useful, just be sure you are accumulating enough time to get the overload and selecting the work to rest ratio to suite your needs.

  1. In a way, yes, I do think there is a benefit to getting comfortable doing those longer ones and sucking it up a bit. If you find that the length is a limiter, I would suggest that from the mental standpoint too, you should work on those to make them feel a little more achievable. As with my comments above, if you can pace this by HR and dial into your feel and perception of the effort, it might make those longer ones more tolerable because you’re not attacking them so hard to get the physiological response. You can actually “pace” them a bit more.

Coach Ryan


Thanks @ryan for the detailed reply, this is really useful.

In response to the general structure of the week when I was doing more polarised work, it was around 9hrs per week, generally 2 x VO2/Anaerobic workouts per week, 1 x Zwift Race & 2 x 3hr rides of Z2 or under (apart from the odd strava segment or hill which would always be >=Z5!). Looking back now I might have still been doing too much in Z3/4, as rough TIZ splits were 65% Z1/2, 20% Z3/4, 15% Z5+. Would you suggest that this may be too much intensity and the potential reason for not pushing on could be lack of recovery/going easy?

Using HR is an interesting one for me, the highest HR I’ve ever seen has been around 181 outdoors (10 mile ITT), and around 180 indoors which is always detonation point. This gives an 85% figure of around 153bpm which I can sit relatively comfortably at around threshold. My 3-5m VO2 intervals generally average around 88%-160bpm (360w ~112% of FTP - doable) to 90%-164bpm (380w ~119% FTP - more regular failures). Would you recommend HR targets as the effort guide during a workout rather than power? Basically aim to get to above 88% and hold it?

Finally I have one somewhat related question which I’ve been unable to find the answer to, since completing most of my base & threshold work, I’ve found that during my more recent Z2 long rides, I have been seeing negative cardiovascular drift, sometimes as much as -5%

Does this mean that I should be increasing the power output in order to stress the cardiovascular system more as the effort is too easy? Should I be using HR as the target here as well and letting the watts sort themselves out?

I hope that wasn’t too much of a brain download and is actually decipherable!

Thanks again,


@stuarthardy I think you could be onto something with your assessment of your TIZ distribution and not seeing those continued gains. In particular, if you maintained that TIZ over the long term (e.g months, an entire season) it could be that you accumulated too much fatigue and never really let that dissipate and get more adaptation.

To your HR question, yes, I would recommend letting that be your guide. You will see day to day variations in HR response. So using HR gives you the ability to track your physiological response (HR) rather than aiming for what may or may not be a more arbitrary power target. So if you can give yourself a power range (e.g., 360-380w based on your previous experience) but primarily use HR, then you can apply the TIZ concept to individual workouts - accumulating “x” minutes at Z5, etc. and then you have the power range to work within to achieve those goals. When I’m doing VO2 type workouts, I’ll aim for time spent above ~85-88% of max HR. Incidentally we have the same outdoor/indoor maximums, so it works out very well to understand where you’re coming from with numbers.

Regarding your decoupling dipping into the negatives, that would be suggestive that you’re putting out more power at the same HR over the second half of the ride. You can see the opposite on this example below showing a ride where fitness was not very strong and there was heavy decoupling in the 2nd half.

This contrasts to your snips above in that you can see that power/HR relationship dropping precipitously throughout this workout, whereas your graphs are showing a shallow to moderate increase throughout. So to your question, yes again. You could bump the effort up slightly to continue challenging the cardiovascular system. If you’re doing maybe 2 hours at a certain HR range, you could 1) start extending that duration, or 2) bump the effort up to accommodate a slightly higher HR. I would also suggest that if you haven’t tested recently, you might go and do a test to see where things are at because it might be that you will see the need to shift your HR zones beyond Z2.

Great questions and observations of your training!


Great thread so far and perfect timing for me to chime in as this Friday I led a Xert virtual group Ronnestad ride for members to get a fitness breakthrough, which was also my first breakthrough since start of November. At that time, my fitness signature was 1110 W Peak Power, 21.9 kJ High Intensity Energy, and 230 W Threshold Power. I set Xert onto “No Decay” setting, which means that changes in that fitness signature is based on work done in each of those systems. My Training Load at the time was 90.

In case you don’t feel like reading to the end, after yesterday’s test my signature is now 1113W, 21.1kJ, 239W. How did I get here and what are my notes?

Since that time, my winter has involved a very polarized focus on endurance and base building, and my TL has remained at about 90 despite a 10 day rest break. For example, my late 2020 outdoor endurance rides would be on the gravel bike at HR range of 105-110 bpm (I have a very low max HR of about 158 and a resting HR of 48, so this is about 55% Heart Rate Reserve), and average wattage would be about 135 W at this pace.

By polarized, I mean that indoor and outdoor rides would be at about that pace, and every week I’d have 1 above threshold workout (Gasoline or Towers in Xert). At the same time, I’ve been doing core/weights 3x/week. I was very dedicated to this polarized approach and the consistency of interval work of these two workouts.

My reflections is that this change in fitness signature is right in line with what I expected given my approach. Built up TP a fair amount (for context, my highest ever TP in peak form has been 253 and my typical TL in summer is also about 95-100) while the relative lack of high-end work means the HIE dropped a bit. I feel that this will set me up for a very good summer 2021, as my TP is close to my peak values and the HIE (also near its historic high of about 23). And it’s just the start of March!

I think the above really speaks to the purpose of polarized training. My overall Training Load hasn’t changed the past 4 months, but I’ve improved my TP by a decent amount.

Another observation looking at how I performed on this Ronnestad workout. The lack of high-end fitness and also lack of high-intensity workouts showed in a great first set but massive drops in 2 & 3. Ave power were 265, 233, 233. HR was also nice, high, and responsive in the first one, but down by a lot in the latter two. But once I’m outdoors riding longer rides and also start incorporating these very high-end workouts this will come.

Hope this gives some insight into what happens with a real dedication to a polarized winter approach along with a diet of consistent workouts at slightly above threshold!



One other addendum to the above. The weather finally warmed up the past week+ to get in some outdoor rides. Basically the same ~2h endurance rides on the gravel bike as last fall where I was riding around 135W ave at 105-110 bpm, I’m now at ~150W at that same HR window.

I am in the same boat(or house), I recent look back has my FTP between 83-86% of vo2max over the last 3 years! I apparently have been slamming my head into the ceiling(easy to do, I am 6’-4"). So, I have already, as suggested below doing two focused Vo2max workouts a week.

As a personal, general training philosophy, the things we hate to do, are the things we need to do the most. I would work on your long efforts at vo2, so yes suck it up! I am doing both being a mtb/cx guy, short/shorts dominate out racing/terrain here, but the long sustained efforts add a greater mental challenge for me.


Couldn’t agree more on the comment about “the things we hate to do are the things we need to do.” Being a MTB guy myself, and @trevor knows this, I loath anything over ~5 minutes. Whenever I attempt to stay on his wheel in the canyons around Boulder it’s a sufferfest for those 40+ minute slogs uphill. He’s loving it; me, not so much. But when the work gets done, the payoff is huge! Definitely appreciate the mental challenge too. It’s not enjoyable, but if you’re required to do it in events, you better practice it. :grin:

Coach Ryan


Hi All,

Apologies for going dark on this one! Work has got in the way of Fun just lately!

Interesting chat, and good to know I’m not on my own here, I’ve also been doing some digging and stumbled across this resource (http://powerspeedprofile.com/). I’ve not done the formal test protocols yet (going to do that next week which will be interesting) but plugged the data from my last seasons power curve into it, as that was pretty well defined. In essence, it’s reconfirmed my issue above, that going at 115% FTP isn’t hard enough for me to target VO2Max and I need to be much closer to 120% (usefully it also gives HR targets). Hopefully it’s interesting/useful for others, I’d be interested to hear your thoughts.

The Dr Seiler Short Stacks video was very interesting, my own takeaway from it was that short on/off intervals got significantly more time in zone (power), but didn’t necessarily elicit the CV (stroke volume & ventricular preload) effects that I was targeting. However as with everything, that’s probably not universally true for all. Unfortunately for me, it appears that the longer VO2 intervals will be more likely to trigger the adaptions, and that’s probably also why I prefer (read: find easier) the tabata style workouts. Am I misinterpreting what Dr Seiler was presenting here?

I’m slotting in a couple of structured VO2s a week, and it’ll be interesting to see the results.

When the weather improves, it looks like I’ll be wearing a groove in the local 4-8 minute hills!


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@ryan and @stuarthardy - thanks for this dialogue. Interesting discussion. Kudos Stuart for having dialed in a perceptible difference btw 160BPM (88% of max HR) and 164BPM (90%). I’ve been wondering a bit about proper targets for HR for both threshold and VO2 workouts. I did 5x5 threshold yest. and avg low-mid 80% of max HR in interval, and peak HR in interval was high 80%. Didn’t hit 90%. Was happy (i think!). For VO2 work upcoming, was thinking 90-95% target, but maybe that’s too high? Ryan noted above that he starts counting above 85-88%. But maybe that’s where individual variability comes in, since Stuart you’e saying that you can hold 88% but not 90%. So, explore what one can hold HR wise for 4x4minutes, and then work on improving that edge? I’ve spent so many years just looking at the power numbers - and have my mental model of my HR abilities left over from running 20 years ago… i suspect i’m inclined to think I can do higher HRs than I really can now that I’m 60. (This all becomes very important for hill climb events later in the year.)


@TKskate, yes, I have a bit of a wider range open for myself. And that lower end is more for my “health” mind, not so much the “athlete” mind where I can still do intervals and put in some hard work, knowing I won’t always hit 90% or higher (e.g., fatigue, day to day changes in HR responsiveness, etc.). On some of those days I might change up the workload and still target something relatively high that will help the fitness in general even though it might not be a perfect interval workout. It’s not likely as large of a response as if I did something like 30:15 or 4x4 type of efforts, but it still works.

This is a workout from ~2 weeks ago that was exactly the scenario. Ended up being 9x5 minutes with 1 min rest at 85-92% of HRmax. HR was not super responsive that day, but still felt good and it just worked out better to target that lower end of the HR range rather than push too much power too early. I was not super well rested for it, but it was still a solid session. DIdn’t hit that >90% HR until the last 3 efforts as fatigue was settling in (as you can see!).

It sounds like you have a good sense for your HR, Tom, having paid attention to it for so many years of training. My take-home is that it’s important to first get in tune with your typical HR responses to different efforts by using real-time experience during workouts and post-exercise analysis. Next, it’s allowing some of that individual variation you mentioned. Once you can work that in, you’ll have a good sense for how to make adjustments, or completely call a workout off if necessary, etc. based on sensations and initial HR response.

Coach Ryan


How we accumulate time at intensity can vary greatly.
5x5min or 4x4min efforts, your heart rate will rise and you will accumulate 3-4 minutes per interval, 12-20 min per workout
Whereas @ThermalDoc will perform Ronnestad 13x 30/15’s, and will have 7-9 minutes per interval set, 20-30 min per workout.

Is it better to have continuous minutes at elevated HR or is total time at intensity the more important principle?

I’ve been performing more intermittent type intervals, 3 sets of 7, 1 min on/ 2 min off.


I have progressed my “ON” power from 120% FTP to 130% to now 140% .
My last work out I accumulated 30+ min over 85% HR max, and 15 min over 90% HR max.
Am I leaving something on the table by not choosing intervals that collect more sustained HR values?


I believe those 1’on / 2’off would target more the anaerobic system than longer ones (3’+) or ones with a 2:1 work:rest ratio (like 30’’/15’’).
Therefore less of an aerobic stimuli maybe?


yes, to your point @shawnfife, what @juliengagne suggested is likely the scenario. The 1 min on / 2 min off structure will allow you to tap into those anaerobic stores pretty heavily from interval to interval with the longer rest periods. I pulled a 40/20 workout from Intervals.icu where that top end power really went away after the first couple intervals. That purple color highlighting the anaerobic zone is very pronounced in your interval set with the 2 min rest periods. In the 40/20 example below, you can see it gradually get tapped out with the short recovery periods.

To your question of leaving something on the table by not chasing intervals that collect more sustained HR values, I think it would help to know what your goal is first. The fact that you’re seeing those gains from 120% to 130% and now 140% for 1 min efforts is pretty significant! If you’re going for improvements in 1 min power, this seems to be working well for you. So in that case, I’d say that no, you don’t seem to be missing anything at the moment. For more sustained high intensity efforts, I would think that the 2 minute rest periods would be on the long side to give you continuous load at your maximal aerobic capacity.

Thank you for those great questions and points!


In the last podcast, Trevor mentioned teaching his athlete to learn to suffer/ride hard during racing.
This idea is part of these intervals for me, my training is mostly made up of endurance and tempo rides. I test using a Ramp Test, 4 min steps, 25 watts per step. I have been ending the test on the 350 watt step, but Xert predicts that I can work well into the 375 watt step.

These efforts have really pushed my breathing/respiration rate and heart rate into uncomfortable levels needed to break through mental, physical, and psychological limits.


Great thread. @ryan one question I have - is the point about using HR to target these intervals that this is more likely to allow you to target your actual VO2 Max on a given day (I’m assuming this exhibits some variability much as (functional) threshold), rather than a ‘best ever’ type number? Or is there something about our bodies’ response to this type of effort that means HR is actually measuring more directly what it is we want to improve (stroke volume etc.)? Or is it both? To be clear on the latter is there a sense in which e.g. at the beginning of an interval if we have a low hr we are not actually causing the desired adaptations until it ‘catches up’ with the work imposed on it (and thus might want to hit the interval hard to begine with)?

Hope that makes sense!

Thanks, @Mr.B. Great question. So I use HR primarily for intervals like these for the same reason I use them in threshold intervals. The power will vary from day to day, but generally the HR response seems to vary less, and I am better able to quickly align power, sensations, and HR to know if the legs are good or not. If they aren’t great, then I know power will be down, but I can likely still achieve the HR response. If the legs aren’t great, and the HR is not increasing as expected, that’s my signal to save that session for another day and get more recovery.

So at the beginning of an interval, we might have a low HR, but we have to look at it in relation to our past response and expected progress. As an example, I’ve been able to get some very good aerobic improvement so far this year, and my HR in VO2 intervals has dropped to a point where it responds relatively quickly and achieves a plateau at a higher power output. Previously, with a less well trained aerobic system, it was easy to shoot the HR up to a higher absolute level and might not plateau as quickly, or at all. So my take-home there is, to your last question, it depends (ugh, sorry!) both on your fitness and on your expected outcome from the session. If you hit the interval hard at the start, that is a great way to work on (for example) specificity for racing, or generate a higher lactate level right away and then work on your ability to tolerate that and combust it at moderate intensities.

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I remember listening to some episode which @Sebastian-Weber said you could expect a certain VO2max with a certain amount of leg training hours per week (10h = 60, 15h = 65). The impression that I got is that raising your VO2MAX requires more than just high intensity? Specifically high volumes of low Intensity at the right intensity = foundation for a certain VO2max?

How important is hitting the right intensity for that low volume base in creating a foundation to improve VO2max when you do the high intensity? How important is doing this volume during the same block you do the VO2max intervals vs. just doing it over months / years?

I tend to do primarily endurance and tempo training with my athletes while continuing to test their vo2 ability.

If the endurance and tempo are continuing to raise their vo2 max power, I continue with the same training until I see a plateau. So basically I am always testing the opposite intensity that I am training to see the effect it is having.

Most people find it hard to do such boring training, so they give up a bit sooner than seeing the benefits it can have for them at the top end.

I tend to build a big base with athletes, then pick appropriate races to bring around the top form before they need to peak.


No issues here with loads of easy miles. My main challenge is finding the time to get that in :smiley: Regarding building base, then bringing top form, how do you manage that if your goal is also the lowest possible VLAmax (triathlon or steady/long time trials)? VO2max intervals during the off-season, then VLAmax reducing work as you approach races?