Vo2 vs Threshold heart rate during intervals

I was just noticing that during my most recent (Vo2) Taylor+2 workout(3 sets of 20 30/30’s @ 130%) my HR for the intervals hovered around 160-162. To contrast, during Mount Grant( 3x 16 mins at 100%) my HR was 169-170 for the intervals. This seems consistent for other similar workouts so its not a result of some other variable(sleep, etc). Shouldn’t my HR be higher during Vo2 intervals than threshold intervals? Would this imply that the short Vo2 intervals aren’t actually taxing my Vo2 system and I should perhaps be doing longer 3-5 min intervals?

Maybe during VO2 intervals which are relatively short, your heart rate doesn’t have time to react? There is a lag with HR.

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I think more than heart rate, you should also look at how they felt. Did the 30/30s get you to that gasping for air/fish out of water sensation? That seems to be one of the greatest indicators that you are at VO2max. Also, maybe consider that the 1:1 work:rest ratio is too low and maybe consider 45/15s or something like that if you want to keep going to short/short route.

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HR takes time to rise up.
It also depends on how hard the 30/30’s are.
Some people’s HR rises / falls quicker than others.

Yes, I think so, also see this thread: Interesting video of VO2master during Billat 30/30 workout

AFAIK, the 30/30s from Madame Billat were designed as VO2max workouts for runners, not cyclists. No idea why they are so popular among cyclists, but maybe because they give us the feeling we are working hard while we are in fact not.

If you want to elicit VO2max with on/off type intervals, you have to go 40/20 or 30/15, which I heard often referred to as Ronnestad intervals: Optimizing Interval Training at Power Output Associated With Peak Oxygen Uptake in Well-Trained Cyclists - PubMed

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1-1 work/rest intervals allow too much recovery on these short intervals. You are barely getting your HR up when you stop and recover all over again. 2-1 is usually whats recommended for the work/rest ratio when doing vo2 but there is still a lot of debate about whether these types of short intervals are really effective compared to long intervals.

I’m crap at vo2 work and really hate it, but find these short interval sessions pretty comfortable and achievable, which always make me think they don’t achieve much!

I thought the point of these short/shorts is that they got you working at maximum oxygen uptake for a more sustained period of time than you can with long intervals. Certainly when I have done them and they’ve felt very productive, my HR has been up where I expect for VO2 (especially by the end of the sets - as above, HR can have quite a lag). I have also done them where that doesn’t happen, and I would agree with the above about shortening the rest intervals in those cases.

To me, they feel very sensitive to my top end fitness. By that I mean, regardless what my FTP says, if I have been doing a lot of top end work then the successive punches are not that challenging because I can recover from them much quicker, whereas at the moment (post off season just starting base again) I will find them very difficult even if the %FTP is the same. So I don’t know if scaling short:shorts off FTP is particularly useful, but I don’t know what the right answer is to that. Adjusting by RPE is probably what I’d do (or in AT I would be marking them easy and they’d get bumped up next time).

I have just done Taylor+1 and yes, my HR was lower than it would be in ,eg. Mount Grant.
That is because the intervals are short and you have 30sec easy recovery between.
But did you find your HR didn’t recover to such a low number as you got to the last set? So you/I were having to start each interval at a slightly higher HR, which I assume results in the intervals getting harder to perform .
Mine was 3 sets of 20. I could have done another set ,but would have had to drop the intensity (from 105% to 100%) to complete it.
This may be why I can manage this type of vo2 workout, but really struggle when they start lengthening the intervals to 3 and 4 minutes. I have to lower thw intensity.

You could also keep 30/30 format and increase it to 150% ftp. I do this and achieve the high HR OP is looking for.
I would not be surprised 30/30 at 130% is easy, bc it is.