Heart rate ranges

Dear All,
I’m interested in knowing how Sufferlandrians compare with the target heart rate zones. I’ve noticed recently some of the efforts cause my heart rate to exceed the zone for a given power target. For example a top end zone 3 power target drifts into a zone 4 heart rate zone. Do I need to reconsider my calculated zones? Should I retest or reduce my power from FTP 5% or so?
All help gratefully accepted.

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No advice for you but I’ve moved the post to the Training category. I don’t pay too much attention to HR myself except as a secondary gauge to how I am feeling. My 2 cents though, is if you are able to hit the power targets even though your HR is drifting higher, I would def NOT reduce the power targets. As a workout progresses, HR drift upward is totally normal even if it is the same effort as at the beginning of a workout.

Have you done the FF to test or are you relying on HM?

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I agree with Sir Glen. I leave the HR metric up to get reassurance that I’m alive. For that, the only zone that matters is >50 (or so). So far, so good.

More seriously, heart rate response to training stimulus is so lagged, so prone to drift as you get hot and dehydrated, and so variable from day to day that I don’t think is a particularly effective metric to monitor cycling workouts. If we didn’t have power meters, it might be the best we could do, but power meters are way better.


Hi Glen,
It’s based on HM, but that was done a little while ago.

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Also - low cadence efforts tend not to get my heart rate up as much as higher(for me) cadences. If your HM was at lower cadence but session is much higher that might explain your observation

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For Z3 and above I wouldn’t worry about the HR zones unless I was unable to meet the power targets for the duration of the interval.

For Z2 endurance and Z1 recovery rides(not recovery between intervals) , I’ll adjust the intensity to get my HR into the correct zones. e.g. when I’ve been feeling good I’ve had to up the target power 10% to get my HR into Z2 on an endurance session, but also had to drop it a couple of percent when fatigued.

I find that HM underestimates my LTHR, and overestimates MAP and FTP
I find that FF gives me a more accurate LTHR ( based on doing long hard outdoor rides), but find the 5 and 20 minute effort hard to pace and sometimes find myself upping the intensity to make workouts as hard as intended based on predicted and actual TSS and IF.

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As others have already mentioned, HR is very prone to the influence of many factors, like temperature, fatigue, dehydration, cardiac drift, caffeine, etc. We know that HR targets are not the absolute best metric to guide a workout, but not everyone has a power meter, so HR may be the best metric for them. It’s also helpful for those with power meters to have a second metric in case power drops out, or to verify that you’re (mostly) matching up in power and HR zones. For example, if you’re hitting your power targets but HR is very low and the effort feels harder than usual, it may be an indication of fatigue and that you need to back off instead of doing the hard workout which could push you into further fatigue.
Also, we do our best to set the HR targets appropriately, but as everyone has different fitness levels, HR response times vary widely. We set the HR zones to where you theoretically “should be” for each interval, but your HR may take more or less time than someone else’s to respond and actually reach that target zone. So there’s some individual variability there which we can’t completely account for.
If you have power, we recommend using that as your primary target metric with HR as a backup/secondary verification metric. Also, keeping your FF test results fairly up to date helps to keep all of your zones more accurate.


Thanks for your thoughts on this. I raised it as a topic as I was comparing the same sessions that I did last year. The power targets are the same but my heart rate is higher. I use a smart trainer now on ERG rather than the crank power meter and manual gear changing to hit power targets. Cadence has remained unchanged.
I did the GCN Endurance ride and heart rate headed north of threshold!
Shall I bin the HRM, or leave it off for the moment?

Hi Jim

If it was the GCN Aerobic Endurance then I personally wouldn’t worry as when I did that one my HR was over the target zones, when I’m usually under or within. I think that’s a particularly hard session - it certainly is for me, anyway.

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Cheers Mickeyfreebs,
It was the similar GCN one, 55 minutes with 1 minute threshold efforts every 5 minutes.
As you say, quite challenging.

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