An 18 watt increase in FTP bumped your endurance rides from HR Zone1/2 all the way up to Zone 4? Are you using the traditional 5 zone system or 7-zones?

I've had similar issues after doing a power test and resetting the zones. And sometimes at the end of a longer ride (using constant Zone 2 power), my HR will drift to the top end of HR zone 2, but I have to be hauling ass to get into Zone 4. Have you done a LTHR test and reset your HR zones recently? I do a 30 min protocol but, I always estimate my FTP and LTHR from the same test. 30-min avg power = FTP and the last 20min of the Test average HR = LTHR. I don't know who's protocols those are anymore. Joe Friel or Skiba or Training Peaks...someone will correct me if I'm wrong.

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Dtyrrell

An 18w increase in FTP should not be a big enough deal that you go from riding at L2 with a HR previously in Z1/2 to riding in L2 with a HR in Z4.

If FTP goes up by 18 the bottom of L2 may go up by ~ 16w or so.

Just add more time to the recovery on the intervals or aim for the bottom of the power range on the interval

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

I think you can expect some adaptation when you bump your FTP like that. That does sound like a pretty big spike in HR zones, possibly you are not recovered enough for those rides, or your HR zones need updating.

My protocol would be to retest LTHR and see where my currently are, and if current zones are correct, revise your FTP.

Endurance rides "should" be mostly in Z2 per Joe Friel (who I am a follower of). I find myself creeping into Z3 (sneaking up on Z4) towards the end of long rides, which I kind of think should be expected due to cardiac drift (your HR going up as you get more tired during a workout).

Recovery is very individual, so you might need to tweak your plan there.

I've always gone by perceived exertion on endurance rides. I tend to look at them as stress free time in the saddle. No big deal if I go a little over and out of the zone from rime to time. Sometimes you just need to enjoy yourself, and endurance rides are perfect for that.

I don't pay much attention to HR on long rides. Too many variables. I'll take note if it's unusually high sometimes and try and figure out why. But I listen to my legs....RPE... to choose the pace unless i have a specific target.

A jump form Z2 to Z4... yikes. That would have my HR at 150 instead of 110-130.

The question I have is how did you legs and breathing rate feel? Breathing rate will be a better indicator of output. HR is a input value and just has so many variables. While breathing tends to follow blood PH due to CO2 concentration.

If breathing is hard at all, your no longer in Z2.

If breathing is easy and your HR is high, then check nutrition, hydration, HR monotor glitch.... but you are not in zone 4.

Keep in mind that breathing lags even more than HR generally.

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TrainingBible Coaching
http://www.trainingbible.com

Try adjusting your ftp down by about 9 watts and see how that goes

OP here. Thanks for the replies. A bit more context:

I think mine might be a case of insufficient recovery. The day after my FTP test, I did a 2 hour endurance TR workout (called Perkins) with power varying from 65-80% FTP (new FTP) and my HR was nicely in zone 2 with the odd peak just barely into zone 3. So I think my zones are fine. But two days after that I did a killer set of intervals -- 3 x (12min at FTP, 3 min easy). Then the day after that I did that same endurance workout again (Perkins) and it was murder -- crazy HR, unbearable perceived exertion. So, instead of recovering from the intervals with my endurance ride (like I normally would), I feel like I just piled on more stress to recover from.

So, this is why I'm thinking that maybe I should just keep my HR in z1, 2 on endurance rides so my muscles can fully recover?

One more tidbit (fwiw) is that I'm definitely on the fast-twitch side of things -- roady with a decent sprint.

Or work in a real recovery or rest day after the intervals. But yeah that sounds like fatigue. Especially because of the intervals being done with the new and improved power zones.

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Dtyrrell