Is a longish Z2 session ruined by dipping into Z3?

Had a 2hr Heseman workout tonight, mostly spent at 75% FTP / 190w

It was pretty challenging to be fair. Felt great to finish it

But combined with my new trainer under-reading by 1-2% and the fact of how much the dips from 190w to 182w felt like a break and dropped my HR, I’m wondering if it was just above by a couple percent.

I enjoyed it and I’m probably over-thinking it, but I wanted to check whether I’m missing out on the Z2 work by having the intensity just that little harder than perhaps intended.



(Somewhat more serious, but longer answer……our bodies are not that precise, as @ambermalika used to say. A few forays into Z3 don’t negate the benefits of the overall workout…and may even arguably be beneficial)


You cannot “ruin” a training session. There’s nothing magical about zone 2.


Except in its ability to garner more clicks on fitness gurus youtube videos. :joy:


You’ve ruined your workout! lol

Why are z2 rides are so complicated? Just ride in an easier pace that isn’t too hard as much and as long as you can. If you go 20 watts into the next zone, it doesn’t matter.

I’m about one more z2 related thread from deleting my account.



While I concede I definitely overthought it and the word ruined is a little extreme, I don’t think it was the stupid question you guys make it out to be.

Thanks for the advice, either way.


It’s not a stupid question, even if the more jaded amongst us will scoff at it. It’s simply that zones have been preached to us incorrectly for so long and now Z2 is a trendy topic that you can’t listen to anything training related without hearing the magical virtues of “zone 2”

Your physiology doesn’t recognize zones. It’s all one aerobic system. In fact as @The_Cog has written, zones are meant to be descriptive and not prescriptive.

Riding with as much intensity as you can recover from is your best bet. Don’t get too mired in what “zone” you’re in.

Easy days should be pretty easy so you can recover for the next one. Keep an eye on your fatigue and go hard.

This is simply my .02 built from study and experience.


This ^^

Don’t go crazy with numbers. If you were outside, how’d do this? There’s no ERG mode, our bodies aren’t machines, relax. Just ride easy, but not too easy.

I’d be concerned that you said the workout at 75% was a bit challenging. Honestly, it shouldn’t be unless there’s some acute fatigue.

I wondered how long it would take the latest Z2 thread to get to “make your easy days easy by riding at tempo”. :rofl:

I heard a dirty secret that your mitochondria have never heard of Z2 or even Z3…


Z2 is such a broad range.

If you’re doing 20 hours of it a week you’re probably going to want to be towards the lower end of the power range in order to recover from that amount of work.

If you’re only doing 3 hours, yeah, push the upper end of the range as far as recovery allows.

If in doubt, 65% ftw!

Or something.


When I say challenging, I think it was more mental than anything. It’s not like I was sweating buckets and struggling to breathe.

I think it’s a combination of the new trainer reading a few percent lower than the old, meaning it was more like 77-78%, the new trainer (2T with motion plates) having motion being a bit more difficult and having never actually ridden for sustained periods on the trainer at the very top of Z2.

Most endurance workouts until now have been around 65-70 sustained, some with intervals of higher.

The little 8 minute dips to 70% were significantly easier. This was the main motivation for posting and asking.

I use plan builder, so just do as I’m told!

I’m on a mid-volume plan, so usually 7-9 hours a week. It didn’t feel like too much, although I was a little tired, I’m coming to the end of this build block.

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Thank you, that makes it very clear.

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Got it.

I understand. I used to struggle a lot with longer indoor sessions. After changing from a Direct Drive Turbo to a dumb set of rollers I’m doing way better.

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Why do you want to go into Z3?

How will you know if the Z2 workout is benefiting you?