VO2 max intervals consistently beat me; does it matter?

I’m currently on the 70.3 distance build plan, and every time I have a VO2 max session I get my arse handed to me. I can usually just about finish the workout, but often have to rest half way through an interval if it is longer than 60 seconds. And today I didn’t get close to completing Julius Caesar +3.

I don’t think it is solely an FTP issue as sweetspot sessions feel perfect: challenging yet rideable.

My question is, does it matter?

My focus for the season is a 70.3 in September. And my other races are increasing length triathlons building to that, with the occasional cycling sportive thrown in for fun. So if all my racing is steady state, should I care that I can’t surge again and again consistently? I’m thinking it might be an issue for “bumpy” routes with short, punchy hills, but wasn’t sure.

I believe the two important take aways from VO2 workouts are pulling your fitness up from the top and the high amount of adaptation you get for relatively small amount of training time. So you should do them but not worry a lot about them given your goals. Maybe replace the plan workouts with something that has the same length intervals but longer rest periods. Then if you have extra time in your schedule it might be something you could focus on for a few weeks.

Another thing to keep in mind with VO2max repeats is the highly individual nature of just what a challenging-but-repeatable 2-3 minute effort really is. There’s no magic to 120%, and it may well be too high (it usually is for me, especially if I just had an FTP bump). Dialing things down 3-5% seems to be a frequent recommendation, and preferable to taking prolonged breaks, skipping work intervals, or not completing the workout. Adjust to whatever it takes to find a challenging but repeatable level of effort for 2-3 minutes.

This assumes you’re reasonably rested; if you’re so gassed you can’t muster even 110% of FTP for 2 minutes, that’s a sign to do something else that day and come back when you’re fresher.


@pkwell is absolutely correct :ok_hand:

If you find yourself consistently failing your VO2 workouts, dial down the intensity up to 5%. You will not want to reduce more than 5% because then you will no longer be utilizing the VO2 max zone that the workout was intended to target.

If you still find yourself failing the workouts, you can try extending the rest periods as well to improve your recovery between work intervals. My favorite way to do this is by using the “Pedal to Play/Pause” feature. This allows you to pause your workout whenever you stop pedalling. This allows you to stop pedalling for some additional time between sets by stopping pedalling (or backpedalling depending on your setup). This allows you to extend the recovery valley without physically interacting with the TR app :+1:


Thanks folks, this is helpful.

Is there a way to reduce the intensity in Erg mode or do I need to switch? I have TR on a MacBook and haven’t seen an option to do that. I’ll be moving to the android app once I sort a Bluetooth HR monitor if it’s easier to do in the app.

I find 120% too difficult and dial the session back down to 96% which equates to 115% thanks to Chad McNeese’s interval intensity graph @mcneese.chad



I’m in the same boat. Longer than 2 1/2 minutes at VO2 and I fall apart if it’s above about 120%. I usually drop the intensity to about 115% (like @GeorgeAnderson) and find it’s challenging but repeatable with a 15-30 second extra rest between intervals on the last few. You’re still putting in a ton of work and making improvement.


What about the VO2max workouts that are more short intervals with less rest, like Bluebell or Clouds Rest?

Do any of you VO2 strugglers use a heart rate monitor? Setting power intervals at 120% is a very generalised method but VO2max and 90% HRmax seem to be a good correlation.

Don’t forget that VO2max is a physiological process, not a power target, and should be trained as such.


My max heart rate is 182. When I do Vo2 work, I I regularly get up to 170 - 174 by the end of the interval.

90% of my max HR is 164, which is a reading I normally get to during Sweet Spot work.

I don’t really know what I’m saying, and I’m not arguing with you. Just curious as to what you would make of those numbers.

As to the OP – I would try some peak-and-fade workouts like Mills (and its derivatives) – the initial pop to 120% gets you at Vo2, then as the power demands start to dip you can hang on while the oxygen demand stays the same.

1 Like

Correlation only after some time for HR to “catchup” and for me its closer to 95% (175bpm is HRmax).

I would look at the MMP curve of the last 6 weeks.
Of you want to do 3 min blocks, than do them at +90% of that max power. That would be better than based on FTP.

It is above FTP were The zones become individual

My understanding is that ramp tests do a good job of estimating vo2max power (max aerobic power or “MAP”). So TR default test does a good job at estimating vo2max power if you look at 5-min power on “Personal Records” (power duration curve) of your most recent ramp test.

From ramp test 3 weeks ago, here is my math showing 90% vo2max power is pretty good target for 3+ min intervals:

  • from ramp test, my 5-min power was 283W (vo2max power) and ftp was 233W
  • my next 3-min vo2max workout is Matthes +1 which uses 115% ftp
  • 115% ftp is 268W (233 * 1.15)
  • 268W is 95% vo2max power (268/283 = 95%)
  • I usually reduce intensity in TR app by 5% which takes 268W target and knocks it down to 255W
  • 255W happens to be 90% of vo2max power (255/283)
  • 115% ftp * .95 intensity = 109% ftp, so for me 109% ftp is better setting for 3+ min vo2max intervals

Yup, for me 90% vo2max power is a good setting for 3-min vo2max intervals. And that means during workout I change intensity to 95%.

1 Like

To elaborate… 90% of HR max isn’t exactly where VO2 max should be, but doing work at or above 90% of HR max improves VO2 max. Picking a high power that is repeatable, and accumulates the greatest time above 90% of HR max is the main goal of the VO2 max intervals. If the power is too high, it’s not repeatable and then you can’t perform them long enough later in the workout to reach the high uptake. 120% is a good starting point, but will be lower for a lot of people.

As for you hitting 90% in SS intervals, I guess that depends if you’re hitting them late or early in the workout and possibly that is actually your true physiological threshold since right now we are just estimating it.


is this your first go with high intensity vo2max?
while it isn’t 100% related to your event, getting good at vo2max and pushing out your ceiling can improve your FTP, which will directly affect your 70.3

Okay, but what do you actually gain from knowing this over just knowing that when you adjust those intervals to 95% they work fine? I have to adjust those intervals to 97% and I know that from trial and error. Sure, I could reverse engineer the percentage of vo2max power according to the ramp test’s best 5-minute power (it’s 93%), but what do I do with that information? Seems like I derived that from the 97% above and I knew everything I needed before. :slight_smile:

1 Like

Most people should just figure it out via trial and error (I did too) and not bother with all that math.

What it tells me - if customizing a TR workout using Workout Creator, I’m going to use 108-110% ftp as my target for 3 minute vo2 intervals. The TR default target is too high for me, at current fitness level.

1 Like

I use the max HR I achieve during a ramp test. Prior to ramp testing, I never got past 180 BPM. In my last two ramp tests, I peaked and crashed at 182 BPM. So that’s the number I use. Do you think that is a decent way to estimate it? In both cases, I only held 182 for about 2-3 seconds.

Using the “estimated” method based on age, my max HR should be 176 BPM.

I would say that I definitely feel like I’m working when I’m in the mid-160s as far as HR. And once I get a few beats above 170, I feel like I’m burning alive :fire:

With vo2max work you are trying to maximize time spent at max oxygen uptake.

Inputs (simplified):

  • oxygen
  • HR
  • carbs

Outputs (simplified):

  • power
  • co2

The problem here is we can only conveniently measure HR and power (and carb consumption). If you go into a lab setting and use a mask, then we can measure O2 and CO2.

And Erg mode uses power target, so if you can map vo2 work to power based intervals it’s easy to do vo2 work and measure progress. Use HR to double check against perceived exertion. Find interval style that works best and use those.

As a point of reference, my max HR from the ramp is 171, my max measured HR within the last couple of years is 175, so I use 175 for cycling and 180 for running and use these percentages

For VO2 it might be better to just use resistance mode unless you’re really in tune with your abilities. Often I don’t watch target power, but time and HR. Takes a little bit of practice on its own and I’m still getting better at it. I like to use the original target power as a starting point, but sometimes it’s just more than what I can repeatably do, but if I just keep spinning at a high cadence and gut through it HR keeps rising and breathing is labored. As long as the power at that specific duration is going up over time, that is what matters.