HIIT: big discrepancy between HR vs power zones

The issue I have is that if I want to be above 90%, MaxHR I need push much higher wattages than the ones prescribed by the Coggan zones based on FTP of 286 (which is in turn based a 20-min FTP test)

My MaxHR is between 193 and 195 bpm, so if I want to be at about 92%, I need to get to at least 178. Per Coggan zones, my high intensity training should between 286 and 343, with the “bull’s eye” being around 309–315.

However, in practice, if I do “hard start” 3 x 6 minutes intervals, I usually need to be at ~480-500 watts for ~1.5+ mins and then drop to 340-350 and stay there for the remainder of the interval. So the average ends up being closer to ~370 watts (that would be ~129% of my estimated FTP). If done well, this looks something like this:

What would you personally prioritize, staying in the watt zone or in the HR zone? I don’t want to over-do it, but I don’t want to under-do it either.

These are the watt zones:

PS Watts probably look high to you, but I’m not actually very fit. This is only because I use an air bike which is full-body, so I use my arms as well (Blitz Air Bike 2.0). My FTP was also estimated based on a test on the same air bike and I’m pretty sure it’s not an underestimate. I reached 193-194 HR during that test, so it was pretty much all out at the end. Also, in general I tend to be better at higher intensities than threshold/easy, likely because my initiallly started with weight training and added cardio much later.

I would greatly appreciate any thoughts. Thank you!

To give a sense of how much weaker I am at lower intensities: I do my easy Z1/Z2 work at about 68–69% of MaxHR (~132-133 bpm). Targeting that HR usually results in ~170–190 watts on the same bike. I can see 160-170 if I don’t keep an eye on wattage and instead listen to a book / watch a lecture. The latter usually results in a more uneven wattage (I go up and down more, so the average is lower).

No. About 8 years ago he updated power to be individualized above threshold:

And % HRmax is another discussion. Just focus on power, and individualize and for hard efforts go max repeatable unless you are working on anaerobic capacity.


Are there alternatives solutions that don’t require purchasing this software that you could recommend?

posted it right above…

a little trial and error, don’t worry, just go figure it out.

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and also, if you have enough max / near-max efforts under 5 minutes, you can inspect your 42-day or 90-day power curve and use something like 85% or 90% or 95% as a starting point. And then figure it out by trial and error.


This makes sense, thank you!

Intuitively, that’s what I’ve been doing I think — even though it has been guided more by HR.

Would 6-min duration be a good one for max effort in your mind, given that my intervals are usually 6 minutes? Thanks!

I dunno, a pro or elite might take it out to 6 minutes, but I’m old and feeble LOL so most of my max efforts are 4 minutes and below, or 10 minutes and above.

@empiricalcycling did a whole load of deep dives on VO2max a while ago. This one I think sums them up and gives some great takeaways on how to do them effectively.Watts Doc #23: Training Your VO2max, and Why Not Rønnestad 30/15 Intervals - Empirical Cycling

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I’ll check it out, thank you!

Coggan’s zones were developed with bike riders so I would be very wary about trying to adapt them 1:1 for a full body exercise like an air bike.

But to answer the rest of your questions…Zones above FTP can be highly independent of FTP and you may be an outlier (like me) when trying to do VO2 workouts.

In a recent VO2 block I went in with an FTP of ~305W (confirmed by a 3x20 workout) and within a week I was doing 6x3 min interval workouts with the best interval avg at ~445W and the average across the 6 intervals somewhere around 430-435W. My peak 5 min is ~420W. So VO2 work was being done between like 140 and 150% of FTP.

For VO2 work you want to basically ignore power and go MAX. You should be breathing like a fish. Use power and HR as a gauge for fatigue (if you are more than like 10% below your personal target then you’re likely tired) and for post workout analysis for possible adaptations (power may rise throughout a VO2 block as you adapt).


Thank you for sharing! This is basically what I’ve been doing. It’s good to know that I’m not the only one as I was a bit worried about overdoing it potentially.