Can’t complete 3min VO2 Max intervals without a 10sec backpedal - am I still getting the same benefit?

Hi all,

I’m in the Triathlon 70.3 low volume Build plan and I’m unable to complete all of the 3-min V02 Max intervals (especially those at 125-130%). I can complete some - but not all. When I can’t I insert 10sec backpedal (usually around the 1:45-2:15 mark) and then I’m able to grit through and finish the interval.

My question: am I actually missing out on the intended benefit by inserting the packpedal?

You get the benefits if you’re over 110%. Try lowering the intensity by 5% and see if you can do it. Then adjust up or down.


How many VO2 max workouts have you done so far?

How many intervals in the last few sessions can you complete before you fail?

How is the rest of your swim, bike, run training going?

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If 10s backpedal is all you need then you’re not missing out on much.

However very few people can repeatably hit 125%+ for 3m intervals. I would’ve thought it especally hard for triathlon types. If you know you struggle with these there are lots of other 3m interval workouts with different intensities. You’ll get more benefit from a completed workout at 5-10% lower intensity than half of the prescribed workout. 118%-120% is more typical for a hard x3min session.


According to Dr. Andrew Coggan, the world’s leading authority on power training metrics, VO2Max training begins at 106%* (although he states that #s aren’t exact). So if you were to look at your average power during the training block, you are likely well above this.

A couple of variations for you to consider:

  1. Use Workout Creator to shorten the length of the intervals, but increase the # of intervals to achieve the same (or more) Time in Zone (TiZ) of the prescribed workout. [this is what I do for VO2max efforts].
  2. Decrease the intensity to a level you can complete the interval block (e.g. 110-115 based on your comments). You can always increase the intensity real time during the session if you are finding the level too low.

*Note: It’s beyond the scope of TR training (at this point) where everyone within the same training block does the same workout. However, in 2015 Dr. Coggan stated that his research (with the help of others) showed that performance (and therefore training) above threshold varied by individual and thus introduced Coggan iLevels. So, for example, VO2max training for you (based on data taken from your Power Duration Curve) would be prescribed with specific wattage ranges for a specific range of time called Optimized Intervals (that are likely different from what you are currently doing) in order to elicit the physiological adaptations desired by VO2max workouts.


I’ve done 3 v02 workouts since starting the build plan.

First was Shortoff +1. I successfully completed 4 before failing the 5th and 6th.

Second was Givens. I successfully achieved the first two but had to backpedal before finishing intervals 3-4 (130%). I successfully did 5-6 (120% and 110%).

Third was two days ago - Owens. After three of them the backpedal requirement for anything over 120% seemed to be becoming a pattern. I successfully completed first 3. 4-6 I had to backpedal. Then 7-8 I was fine (they were lesser intensity).

Do I just need to HTFU or what???

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…also re: other workouts. I’m not using the set TR run and swim workouts - I think they’re pretty sub par. But FWIW - I’ve always found I can SMASH myself in the pool without it negatively impacting my indoor bike workouts. And they’re never on the same day anyway. As for runs - my main goal is to increase FTP on bike, so I’m almost never running above z2 in order to aid that. In other words - running is going fine because it’s dead easy. Only totalling 2.5 hours running and 3 hours swimming a week.

Some good thoughts there. However I’m actually achieving the full 3min intervals at v02 max - the full cumulative time, that is. That’s without lowering the power target too. It’s just with a 10sec backpedal/pause in the middle. So not sure your 2 points have given me much direction there.

I agree with @Alen, try reducing the intensity a few %. However, at this moment, what you are doing is probably not pointless.

If you want to read more check out our recent Time at VO2max discussion

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You could also use their alternates; Shortoff and Givens -1 which switch from 3min to 2min intervals.

How did you do in Base with Dade -1, Baird -1 and Mills? (Mills is a toughie imo)

Base should have put you in a position to complete these as is, but no shame in building up to them again.

You are doing the “bail out” correctly. The short 10-sec backpedal keeps your aerobic system near maximum.

Not everyone is capable of doing vo2max intervals at 120%, and some find 120% too easy. For that reason the workout notes instruct you to find repeatable power and use what works for you. Sounds like you are close, and might benefit from lowering intensity a little bit (or keeping the same and gritting thru them).

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My advice would be to complete these types of workout in resistance rather than erg mode. That would allow you to complete the intended interval duration without the need to back pedal at a level that you are capable of achieving.

I often find a point during the harder VO2 Max intervals where my cadence can slow slightly and the power can drop maybe 10 or so watts before increasing again. If you’re in resistance mode this just forms part of the natural power variation within an interval and there’s no need to stop. In erg mode only a slight drop in power can lead to that need to halt the interval.

You can then either undershoot the target by a few watts and still get the intended physiological improvements from the workout, or conversely if your having a good day overshoot the prescribed targets and feel smug for the remainder of the day :wink:


This is an interesting idea I may need to try out. Currently struggling through short power build plan on the vo2max efforts. I find that in erg mode as I am getting towards my limit my cadence slows which makes erg kick up the resistance and it forces me into a failure. But using resistance as you say I could possibly drop the power slightly and maybe last through the end of the interval. I would be curious to hear coach Chad’s take on this if that still stays with the intention of the workout or if lowering the overall intensity would be better.

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time in the zone is where it’s at, so use the backpedal and you’re fine. I wouldn’t lower the intensity though

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Don’t know about anyone else, but when I backpedal, I get immediate relief usually coincident with a dip in HR. Not sure about ventilation. With VO2 work, I tend to adjust intensity, saving the backpedals for the longer muscular endurance work. As you said, VO2 is about time in zone, specifically time with max O2 uptake, so whether you’re backpedaling or reducing intensity - still in the zone - either is viable, and it just becomes personal preference. If he can adjust intensity from 120% to 117% or 115% and survive without backpedals, that would work well.


Agreed with the advice around using resistance mode.

Fun fact: any duration above threshold will eventually elicit VO2max, but you also have to layer in the other energy systems especially towards the front half of the workout.

These intervals get progressively more “aerobic” as you do more of them (as you deplete anaerobic work capacity), so you could be working at a lower power over time but still be eliciting the desired VO2max response.

So as long as you are going as hard as you can for the stated interval duration towards the end of the workout, don’t worry so much about the power unless is dramatically off target.

(Note: this only applies to VO2max workouts)


The problem here is we can’t conveniently measure vo2, and so it requires triangulating with power, heart rate, and perceived exertion. Or using WKO4 and using its estimates based on your 90-day power duration curve.

Billat has an interesting study about “hard start” vo2max efforts: and if you look at Figure 1, subject A has ftp of 300W and did 400W for about 90 seconds and then went below FTP for most of the remaining 14 minutes, while still maintaining the aerobic/vo2 level of doing a constant 400W for 4 minutes.

In other words, around 16 minutes of max aerobic effort in a single “interval” instead of 4 minutes. BUT you need a vo2 mask to know you are operating at max aerobic because subjects B and C reduced power to ftp and slightly above ftp. Would love to get one of these masks for vo2 workouts: but its the cost of a fancy new carbon bike.

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Good stuff there.

I actually did Mills for the first time today. I replaced it with Dade -1 my first time through, and I’ll tell you, Mills sparks some ideas similar to what you linked. I dialed up Mills by 4-5%, starting the intervals at 125-126% of FTP, but ending down around 112% for the 2 minutes, and my uptake stayed right about where it should be for these types of workouts, but it was likely easier on my legs. I can see some real value in those “hard start” types of intervals for prolonged time at max uptake, but there’s probably a pretty fine line in terms of how much you can actually back off the power to achieve that and it’d vary from person-to-person.

It may be something I dabble with myself because I have a pretty good feel for my own personal VO2max efforts… I think it’d be hard to really program it for most athletes unless you’ve worked with them for a long time and can trust their feedback or are directly observing them during these workouts.


Here is the WKO4 relative VO2max for Mills -5 that I did last night:

I customized the chart to remove HR and a few other tweaks.

It certainly felt like 100% vo2max was reached. Dropped the power in 6th interval, felt like my heart was going to explode and head was pounding - and you can see 6th intervals doesn’t hit 100% vo2max. Going forward I’ll disable auto-pause in TR, because it screwed up the vo2max estimation in intervals 5 and 6 (had to take short backspins).

Would really love to try and validate the WKO4 estimator, and I know a local training company that has an oxygen and lactate test equipment. Hmmm…


I think you were the one who turned me on to Golden Cheetah direct from dropbox. I’ll have to poke around and see if there’s similar functionality there. Might not be 100% accurate, but interesting nonetheless.