Zone 2 Power vs Zone 2 HR (Should I increase power to move HR to Z2?)

Lets start with Coggan remarks from 2003 paper he wrote for a USA Cycling coaches seminar on power based training:

“HR guidelines: Relating or translating the specified power levels to corresponding HR ranges or zones is somewhat difficult, due to the inherent variability of HR as well as individual differences in the power-HR relationship (even when referenced to threshold power). Nonetheless, approximate HR guidelines have been provided in Table 1, such that they can be used along with power to help guide training if desired.”

And table:

And using my threshold HR as the anchor, brought me to the which zone dilemma:

  • Coggan zone2 for me is 110-134bpm
  • Friel zone2 for me is 128-142bpm

big difference.

That bothered me, so when I got into cycling back in 2016 and 2017 I figured the thing to do was go out and do a bunch of 6-12 hour rides. Then looked at average HR and called that “all day” HR, which was 136-142bpm.

Pretty clear at that point the Friel zone2 HR align with all-day HR, for me.

Yes, but why complicate it? I would just do it the way that it was described it in that Attia podcast with Iñigo San Millán. Go by RPE. Extend duration week by week. Let the numbers be what they are, and use them more to evaluate the workout after the fact.

Interesting approach. However, doesn’t it get a bit more complicated due to the climbing/descending dynamic?…

Don’t overthink it.

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Well, it’s inevitable. I just took a look at a long ride where I averaged 144bpm but in the long climbs my HR was 155-166, which is tempo. So this wasn’t a z2 ride as the average would have you believe.

Pre power meter:

8 hours of climbing, 13:51 elapsed. Done at ‘in it to finish it’ but pace was endurance climbing and mostly nose breathing. Average HR between 134-140bpm. Average temps for each climb in F and C:

  • 44F / 7C
  • 65 / 18
  • 74 / 23
  • 80 / 27
  • 69 / 21

First climb, top of zone2 is 142bpm:

Third climb w/o the early 15 minute stop

Fifth climb:

Yeah I’m a slow climber, that was done with an FTP of around 3W/kg.

So ~8 hours of climbing over ~14 hours I think its fair game to call “all day” HR for the climbing portions only.

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and another one pre-power:

and Friel HR zones:

and elevation:

*** that was then ***

Now fast forward 6 years to the present.

Two hour Tuesday last week (outside with temps in 80s):

Two hour Tuesday this week (in cooler gym):


Ok that HR pic needs some explaining. First off HR is unusually low due to being fully heat adapted (“80s are the new 60s” LOL) and the gym was 66 degrees (108 outside). Secondly, the power increased too, and decoupling was 0.4% which is basically no decoupling of power and heart rate over the full 2 hour workout.

I dunno, it all adds up from my chair.

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Thanks for sharing. Yeah it seems that the heuristic works for you. I can climb at endurance HR and power when I want to, but in general for the very long rides I try to push harder in order to minimize time in the saddle.

What is interesting about this discussion is that is very hard to have “organic” data for long rides, given that most of us have employed some sort of objective pacing measurement in addition to RPE.

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Not that hard if you want the data, and go out and do long training climbs or flat rides. After getting a power meter, I started pacing long 90-150 minute HC climbs at mid to upper tempo. Now I’ve got zone3-zone4 data to complement the earlier zone2 data.

Key thing to remember is that context matters. And that means either planning or cherry picking data.

The only thing though is I am not looking for what I can do, but what I should do for the best training.

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well that depends on who you talk to… and whether you want to do lactate testing or not. And ‘best’ in early season is likely not be the ‘best’ during race season. It also comes down to goals and durations you are targeting. And ability to recover from the endurance work. Some coaches will tell you to simply do endurance by rpe. My coach pushes me to pay close attention to how I feel, in order to figure out the push-the-z2-power and recovery balance point.

My position on my “all day HR” methodology is that it is an ok proxy for the first (aerobic) lactate threshold. I can do epic long rides, keep my average HR under 140bpm, and usually recover quickly. So they are relatively low stress. Like doing a double century at 67% IF / avg-HR 131bpm and 2 days later going straight back into training and setting PRs.

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fair, and anyways, like you and others have said a few times now, no reason to overthink this stuff. The fact that one is getting outside on the bike for 6 hours, and keeping it close to Z2 as possible, is going to do well for fitness gains, period.

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Should we increase the power when the HR decreased for the same WO?

After a while I’ve noticed that my hr has become lower for all z2 endurance wo. So low that it’s almost like I’m doing nothing!

Should i increase the power or keep it like that and extend the duration?

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I adjust the power to keep the same HR. As you train in Z2, the power will keep getting an higher percentage of your ftp.


Similar question, but I am having the opposite problem from OP. Beyond a certain duration of riding in Power Zone 2, my HR rises above HR Zone 2 during the ride; should I reduce power to move HR to Zone 2??)

This past weekend, I tried to do a “proper” Zone 2 ride (based on power). I rode for about 5h 41m at a power level that was about in the middle of Zone 2 (AP 191w; NP 192w). I took a short break of about 6-8 minutes in the middle of the ride to refill my two water bottles, put some more gels in my pockets, and to pee. I set the “auto lap” feature on my Garmin to start a new lap every hour. During the ride, I noticed that my heart rate gradually increased during the ride, to the point that I getting my HR Zones 3 and 4. Following the ride, Garmin categorized it as a “Tempo” ride–that’s when I started to think maybe it wasn’t a “proper” Zone 2 ride after all.

When I ended the ride, I felt great physically and mentally. The next day, however, not so much–it was then that I realized that my “easy Zone 2” ride was actually not so easy and required more recovery than I anticipated. But I don’t know if that’s necessarily a bad thing; is it? My goal is to be able to sustain my Zone 2 power over long durations (12 hours and beyond).

If I were to do this ride again, should I (A) target the same power (193w) but increase the duration; (B) lower the target power to something closer to the bottom of my Zone 2, but hold that power constant for the duration of the ride; (C) gradually reduce my power target as HR/RPE increases?; or (D) target the same power throughout the ride, but stop if HR goes past a certain point (and what point is that?)?

Also, was the 6-8 minute break in the middle of the ride likely to significantly impact the effectiveness of this ride in terms of building endurance for longer rides? If so, what would be the best way to work around that–have someone come out and hand me bottles and gels??

What seems like a simple topic all of a sudden seems enormously complicated and confusing to me.

TrainerRoad and Training Peaks charts below:

Screenshot 2023-01-11 at 11-04-18 TrainingPeaks - Plan your training track your workouts and measure your progress

ETA: I was chased by the same dog twice during this ride, and I increased power slightly to try to get away from it.

I have this issue. I have a 20-30 beat discrepancy in my power zone and HR zone. If I’m doing endurance or vo2 max, i’m in the “right” power zone but my HR one doesn’t match. At the beginning of vo2 max I’m 50 beats below and at the end I’m 20 beats below. Endurance I’m 20-25 beats below endurance HR when my power is in endurance zone. Does lactic acid build up always coincide with HR in terms of zones? A lot of the times my legs my be burning/hurting in a threshold or vo2 max workout but my HR is still in endurance or low tempo zone.

Some coaches say yes, to trigger the correct adaptions. Ride 1/2 to HR and anything above to power (ignoring HR, unless you have a medical problem of course). Although with TR workouts myself I tend to use power all the time as their workouts tend to cross multiple zones. Only outside do I use HR alone, if I’m doing a pure Z1 recovery ride or I want to stay fresh for the next day (I tend to keep it below 75%MHR (approximately Z2 depending who’s zone you are looking at :wink:)).

As to your break I doubt it would have done any harm. I use carb drink and avoid gels unless its a race or an emergency pick me up but we are all different.

Number one rule for me, don’t over think it and just ride :wink:

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the coaches I follow, the ones that have been using the aerobic decoupling metric for a long time, my understanding is that answer is no. It was first used as a metric to determine when you’ve done enough low aerobic training, and it was time to move on to doing tempo and threshold work. It has also been used on higher intensity (upper tempo and threshold) intervals as a signal to do more endurance (low aerobic) work.

However, it is hard to give advice without knowing more about your training and the details of that ride (hydration, nutrition). For example did you jump from doing 1-2 hour endurance rides to this long/steady endurance? Just one of a handful of questions off the top of my head.

Also, your entire ride’s Pw:Hr in TrainingPeaks is less interesting than removing the first 30 minutes and looking at decoupling of the steady portion (including break) after the warmup.

The Garmin auto-lap is a distraction and not really helpful, from it I can tell you the hour to hour decoupling but nothing else. TrainingPeaks premium has tools to select a portion of the ride and get Pw:Hr. And other analytic platforms have it as well.

The one thing I can say for sure - don’t worry about that 6-8 minute break and “reducing effectiveness” of the workout.

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Thank you for the insights and information.

I appreciate that, and I guess I was looking for more general guidelines as to whether I am doing Zone 2 “the right way.” FWIW, I consumed about 90g of carbs and a 26 ounces of hydration mix (electrolytes) per hour.

Last year I tried to build up to 6-hour long steady endurance rides, adding a half hour each week, but this was the first time I was able to do one on a course that allowed me to ride without stopping or breaking my pace for the duration of the ride. Also, I probably was not always very disciplined about staying exclusively in Zone 2. :frowning:

Thanks for the tip. I keep in in mind going forward. FYI–Excluding the first 30 minutes and the cooldown, Pw:Hr for that ride is 7.44%.

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the “right way” is in the eye of the beholder LOL. For me its doing more 2-4 hour steady endurance training rides at 66-79% ftp :wink: and saving the long rides for group adventures. But if you are training for ultra events, that one looks pretty good and after some more steady endurance riding your decoupling will likely come down. Anything under 5% is a win, given that outside you can’t control every environmental variable.