Power Zones vs HR Zones

I did Baxter the other day and I uploaded to intervals.icu.

I noticed while the power zone was all Z2 endurance (which is what I wanted). It listed almost all my Heart Rate (HR) Zone as in recovery instead of aerobic.

So does that mean I’m not really getting an aerobic benefit? How do you balance the power zone w/ aerobic zone? If I push power too much, I get out of the endurance work zone.



HR can be a crap shoot, I wouldn’t worry too much about, How long has it been since you tested? Might be an indicator that it’s time to retest.

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I’m due to re-test Tuesday. Sort of dreading it… LOL. This week is a rest week so all easy rides. just wrapped up low volume power build.

If this is your rest week, then you really aren’t looking for any sort of gains anyway - recovery is what you’re looking for!

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First thing to consider is how are you calculating HR zones, and your HRMax in particular?


I wouldn’t put too much stock in generic heart rate zones, there is just too much variability. Most heart rate zone calculators just take your max heart rate into account, but not resting heart rate.

Mine is 45–50 bpm these days. During workouts my heart rate stays low. I have to push really, really hard to get it beyond 165 bpm. Even long efforts at FTP just get me up to 160–165 bpm.

More important than the number, I’d look at how quickly your heart rate decreases in recovery valleys. How many seconds or minutes does it take to go from heart rate at FTP to Z2 heart rate? If that happens quickly, usually that’s an indication of good fitness.


That workout was just about perfect for you if aerobic endurance was your goal. Looks like max HR from your last ramp test was around 165. You were in that 70% to 75% of max heart rate zone during a lot of the Baxter workout. Bob’s your uncle. Good job.

You can adjust your HR zones manually on intervals.icu if you want. I have mine set to match Ronnestadt’s HIT/MIT/LIT HR ranges, for example.


I’m going to have to do more research then on setting my HR zones right.

I hit 165 and I’m usually tapping out within a short amount of time.

Sweet spot I’m usually in the 145 - 155-ish range depending on what I’m doing/workout.

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Honestly I was using an estimate of around 170. At this point, I haven’t done much digging into setting a more scientifically determined HR max… I know on ramp tests I tend to bail around 165-ish.

I had one outdoor ride over the summer where I averaged around 160… I was looking at it the other day… I was sort of surprised… but that was one of my best efforts last year… Trying to hang onto a group of guys faster than me and not get dropped.

FWIW here is one of Ronnestadt’s papers http://umh1617.edu.umh.es/wp-content/uploads/sites/546/2016/05/Ronnestad-et-al_block-periodization-cyclist_2014.pdf

And zones:

  • LIT HR: 60-82% HRmax
  • MIT HR: 83-87% HRmax
  • HIT HR: 88-100% HRmax

Additional FWIW - those zones are almost identical to what I use for my 3 zone HR charts in WKO.


Thanks @bbarrera , you always come through with the good info…

I’m on the same page as Brennus on the 3-zone HR model, although I arrived at it from a different direction (Friel and Coggan zones plus my own experiences).

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Just test for your max heart rate, then you’ll know what it actually is. Failing that you could do lactate testing to find your thresholds, if you were prepared to spend the time/money

Pretty sure one (or both) of these has some advice on how to do a max HR test:

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