Endurance Workouts based on Heart Rate

When it comes to endurance day, I know what I’ve got coming in Pettit so on the whole don’t really bother following the workout and maybe just cruise around for an hour or so doing roughly similar IF on zwift or the like.

It got me thinking though, with the normal intensity of TR workouts, we’ll generally be skipping training aerobic threshold outside of endurance day. Which also got me thinking that maybe endurance day workouts would be better suited to target heart rate than power.

I also often do endurance either no-fan and/or fasted. Today was powered by doughnuts and no fan… At 45minutes in and 180w my heart rate was starting to creep into high Z2, so I turned on the fan and I had to then increase to maintain a shade over 200w to keep my heart rate from dropping into Z1.

That makes me wonder if I’ve not been taking endurance day seriously enough? Is power that relevant in Z2 for the adaptation we’re looking for?

Yes it is. I can drink 10 espressos and ride and roller coaster and that’s not offering any type of workout. It’s better to train at the prescribed wattage. If you can push more wattage in Z2 with a fan on then off it makes sense to use the fan.
It’s like how Nate was wanting to use his sleep machine while training so he could get more oxygen while riding.

Target power. You might want to review aerobic decoupling on longer (90+ min) rides to determine your level of endurance.

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100% I’d agree for anything Tempo or above, though as I understand it, the adaptation we’re seeking by riding this low zone is to raise the heart rate point at which the body starts relying more on glycogen than fat for energy.

If that’s the case then doing it fasted/no-fan is giving you some nice freebies. If it’s not the case, then fuel the workout/use the fan. Aiming for power, well 1 or 2 z2 hours a week doesn’t seem like it would really do anything much for building base fitness?

I spent a lot of time in Q4 doing long Z2 rides (2-4hrs). While i went off a wattage target I did use HR as a bit of an engine temp gauge to see how things were doing.
I found a wattage target whereby I could sustain 140bpm over 3-4hrs without a ton of drift. This is not attainable through standard TR workouts because even the endurance rides touch on the endurance/tempo limit so your HR goes up a little too high.
I found for me starting out 185w was my ceiling before i started getting a lot of drift later in the ride. Started banging those out weekly on Sundays and at the end of my regular workouts to extend time.

As I kept doing those my HR for those efforts started to drop, so I would slightly increase the wattage target 5w or so, keeping things around 140bpm.
Now i’m doing stuff at 230w and keeping under 140bpm, so things have dramatcially improved in 6mths.


@RONDAL Were you following a TR plan with extra endurance rides, or just riding long Z2?

mix of both. i used sept-Dec last year to build out my own stuff really targeting my aerobic capacity.
I dont want to get into a Sweet Spot vs. Traditional debate, but I ended up using some pretty standard stuff and built out my own plan. Again I find some of the endurance rides too high % wise and wanted to avoid that.

LOTS of Z2…like 70% of a week, and mix in some long tempo onto the ends of them to really stretch stuff out and grow the aerobic base. Then I went into SSB1, 2 and currently working through Sustained power. Really seeing some big gains right now as a result of the solid base I cultivated. FTP has jumped 50w in 8 weeks as soon as I started adding some intensity to things.


I get fasted rides and adaption but unless you’re specially training for a hot race it doesn’t make sense to not ride with a fan. The amount of work you can do without is so much less both time and intensity. Doing 2 hours on the trainer without a fan isn’t going to prep you well.

Riding with fans on at 250 watts for two hours without calories is a better adapter then riding 180-200 watts no calories and no fans. (Wattages will differ between people, just put some Z1-2 ranges I see)

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@empiricalcycling has a great episode discussing this exact thing. As always with his stuff, it’s well worth the listen.

He mentions around minute 33 his usual Rx for his athletes is going off RPE of 4-5. This is one of those that isn’t super black/white as following Power and HR both have drawbacks/upsides and I have found my long endurance rides to be enjoyable and time well spent going off that low/mid RPE.

I personally think there’s too much variability in HR (especially as the father of a 6 month old) to train by it; I use it as a gauge over time and as an individual data point on workout to workout


I think it all depends on your aerobic capacity. For me I’ll always go off HR for endurance rides as I don’t want to ride in Z1 HR for most of it. I generally increase the intensity by 10-15%, so my HR is closer to my top end Z2 range. If I don’t do this then most of my endurance rides would be Z1 or very low end Z2, which I’m fine with for a few mins recovery between intervals but not for strict endurance rides.

There are benefits to endurance rides in the heat that carry over to cool climate performance. Increased blood plasma and faster sweating response carry overall benefits regardless of what climate you’re competing in. That said, higher intensity rides should be done cooled otherwise the workout could be compromised.

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For those of you not listening to the podcast… HR is not indicative of “aerobicity”. But then again in a lot of ways, neither is power. RPE pacing means you can adjust for whatever you need on the day, and also as you go through the ride, without having to chase a number, and your riding will be just as effective, if not more so.


In addition to Z2 by HR, RPE, etc, try regulating by breath. Once you have to start breathing through your mouth, you’re probably going too hard.

These heat acclimation benefits may be retained for 1 or 2 wk…

As previously mentioned, a practice best saved for closer to race day…whenever those return.


HR user for long endurance rides here, i’m working on decoupling however noticing what my HR/power would be at the start compared to hour 3, my HR is entering high tempo/sweet spot by that point.

Ha cheers that’s what I get for skipping in halfway through a thread :sweat_smile:

or for those of us living and riding in hot climates…

Might I also introduce tracking efficiency factor, which is just avg power/HR on each ride. Over time if you’re getting more fit, it goes up. Here’s a good example. PwHr, which is decoupling, on a steady trend down as well.

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Those rides are limited in time. Yes they serve a purpose but should be done leading into a specific event. Otherwise which is more beneficial overall fitness: two hour ride at 75% ftp with fans on or 45 min ride 60% no fan?

I agree the first is definitely more beneficial👍.

I mostly just ignore HR at the moment. I only use it limit efforts on my road bike (no PM). My legs aren’t back up to speed with the rest of me yet. So it doesn’t really reflect lower efforts very well. I’ll sit in Z1 - low Z2 for endurance and tempo work. Sweetspot is still Z2. It only really gets going at threshold.

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Is this a standard chart in WKO5? Or is this one custom? Your knowledge has been helping me a lot lately, Vo2 series is awesome!