Zone 2 Power vs Heart Rate

Hello, I started with training plan after two years of unstructured, but regular riding, mostly around treshold. To hold Zone 2 Power my heart rate goes to Zone 3, even when Im rested. However, keeping around treshold still feels pretty easy. Zone 2 should be about improving aerobic, and that is related to both muscles and heart. So, I dont know which should I follow, power, or heart rate, for my zone 2 rides. Any advices?

How are you defining the zones for both HR and power, first of all?

I used HR monitor for a longer time, so my max from some KOM rides that had me puking at the end. Zone 1 is 60% and then each 10% is another zone. Default setting on my Garmin. Power is based on FTP test with powermeter outdoors. 9 Coggan iLevels, where zone 2 is 54-75% of FTP. Again, default Garmin setting.

If you are confident that your FTP is set correctly, I would go with power. There are just way too many factors affecting heart rate.


So is 55% FTP getting you to 80% HR? That seems off to me…


No, when Im at low end of power z2, 55%, then Im at the edge between HR z2-3, so around 60% But when I get closer to top of z2, 75% of FTP, thats where HR is close to 80%. To me it looks like my endurance is so untrained, because I always did fast rides, that even 75% of FTP is too much and its getting to tempo HR because of that. There HR goes up only slowly, and higher zones are as they should, HR compared to power.

I added picture to original post. Thats flat consistent ride. It was only 70m of elevation over 50k. Just occasional surges on light or overtaking on busy cycle path.

It might be worth looking at calculating your zones using heart rate reserve. If you Google Joe Friel heart rate zones you should find it. It takes into account your resting heart rate, so if you’ve a higher resting heart rate (typical of someone new to the sport or without an endurance background), it’ll adjust for that.

I’m the other end of the spectrum from you much lower heart rate, typically Z1 HR for Z2 power. I find using that method much more accurate for me.


There are many discussions on this subject. See here for further detail:


I think your best course of action is to take a deep dive into those links @onemanpeloton posted.

Continue to use Coggan power zones until you have a good reason to change (e.g. coach’s advice, fun experimentation). Most cycling power metrics and discussions center around those zones or assume a knowledge of this system. It’s the standard.

To me it just looks like you need better HR zones. Friel is a good place to start, but is by no means the only one.

As you read through those links, maybe the most important take home is there will never be an exact, perfectly lined-up matching between HR and power zones. That’s just not the way it works. This is particularly true with the way they are named or labeled.

Finally, try to avoid analysis paralysis. Settle on an established set of zones and get to know how your power zones typically relate to you HR zones. It will be individual to you.

As said above HR zone almost never line up, my Z2 power results in Z1 HR.

This might be usefull. Source Highnorth Performance

If doing Z2 power results in Z3 HR that normally does indicate an under developed aerobic system in general.

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Yes, thats what I was thinking. Thats why I dont know if I should stick to power or heart rate for zone 2. Because if Im riding in power 2, but heart rate is above what would be low effort, that means im already consuming more carbs and producing more lactate, that would improve high aerobic and not base, right? From threads linked here it seems to me I should do HR zone.

By the way, thanks to everybody who replied, your help is appreciated :slight_smile:

In that situation, I’d personally try to accumulate a lot of time at the lower-mid end of z2 (power), and keep an eye on HR (cardiac drift). If it starts to get well into z3, maybe pull back a bit. Hopefully over time you’d see HR trend downwards for the same power output.


Same, that would be my suggestion also.


There is no a priori reason to expect that HR-based zones and power-based zones should agree.

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Glad you agree.

This is the default setting:

Source: Edge 530 - Heart Rate Zone Calculations

I didn’t find those zones useful.

You have some control over HR zones:

I’m using % Lactate Threshold HR (LTHR), it has worked well for me for 5 years. The test protocol I use for LTHR is the Friel test.

These are the LTHR based zones I have setup in Garmin Connect:

Okay, thanks a lot. Thats actually what I was doing, keeping power in the middle of Z2 and slowing down when HR got near the max of HR zone 3. So Ill keep doing that. Also, I didnt do Friel test, but taking my average HR from some near 30 min max effort, those zones seem to be closer to power zones. So Ill do that test and see what Ill get.

Regarding zones, there are several common zone systems. And they all give different results. For example a 2 hour zone2 ride two days ago:

Top is Coggan HR zones, bottom is Friel HR zones. Both use LTHR. Both give very different views. When I ride zone2, I train to power and ignore heart rate (note: except for special circumstances). Have been happy with the results of using power only for zone2 training.

And Friel mapping from 1-5c to names:

And here is Garmin Connect view using my custom zone settings based on LTHR:

I happened to start 5 years ago with using the Friel HR zones. They map fairly well with my power zones. So I am happy using Friel HR zones.

Here is a long list of HR zones models:

Personally I believe HR zones based on LTHR work well and recommend them, however there isn’t one right answer.


I went to some effort to get power and HR zones to line up in to be able to better compare rides without power (e.g. when I am on my MTB) to ones with power. I used Friel zones based around LTHR. This is me from last year. Nearly all rides done with power and HR. The HR data lines up very nicely with power: has a bunch of power/HR metrics that can tell you all sorts of interesting things. In particular what HR is required for a given power output will show progress (or otherwise!) without any kind of testing.