Low vs. High Z2: whats the difference?

I remember finding a link to an article talking about the difference between 55-65% and 65-75% FTP (and why higher isn’t better). Can anyone point me in the direction of that article?

No, but. I am sure it would relate to higher metabolic cost / fatigue verses reward.

Minimum effective dose, is often cited. Once you top out your hours per week you then start increasing the TiZ (time in zone) and a step in this is where you are within a zone lower, middle, edge. By edge in this case I mean Endurance/Tempo, so 75%.


Was it this one?


I don’t think it was that one but it is a good read! @brendanhousler is an awesome dude and really knows how to present information well. Reading the article did jog my memory and now I remember that the thing I’m thinking of came from a WKO4 webinar. The basic idea was that if you are spending time in zone 2 then you are better of doing it in low zone 2 because according to them the additional stimulus of reaching higher up in the zone doesn’t justify the added fatigue. I’m sure I am missing some details and caveats but that’s why I’m trying to find the source. :slight_smile:


This is something I’ve really learned over the years. I started replacing any TR endurance rides with the -1 versions or just dialed them down. Its been fairly successful from what I have seen.

I think it’s all time dependent. At present with no racing I am doing plenty of easy zone 2 where I am out for 4 hours/day on a weekend and 2-3 hours/day during the week after work (from home so I get to add my travelling time to my workout - especially as it’s summer and the lights good). However in the winter or when I am travelling to work I use a shorter 3 hour outdoor ride at the weekend but push the intensity a bit and of course use the TR SS sessions during the week and when the weather is crap. Even endurance turbo sessions like Boarstone etc are more intense than I would ride zone 2 on the road…but of course they are half as long :smiley:


i believe it was the Art of Intervals and he says go middle of z2…but he does mention that there is SOME benefit, and honestly that’s going to be insanely hard to track, so if you are pushing 75% and dont feel like you’re overexerting yourself and HR is normal, do that; otherwise, cut it to 65% and don’t beat ourselves up over not being at the tippy top of the zone.

hope you’re having some good rides!


Yes, it was one of Tim C’s webinars (funny enough, I was trying to find this last week).

Tim has mentioned the whole zone 2 thing in some of the more recent videos too.

Agree with this, and it’s also phase dependent. E.g. During Build or Speciality you will have 2-3 hard and/or specific workouts each week that you need to absolutely nail and therefore be fresh for. Going too hard on the easy/endurance days can compromise that. But during Base phase when all or the vast majority of the work is below threshold, I find that simply accumulating TSS is a pretty good measure of how big a base I’m building. And high z2 or tempo at the volumes I do (typically 10-12 hours/week) allows me to accumulate more TSS than low z2 and without becoming unduly fatigued.


Yep - the harder the workouts you have in your plan the more polarised your training needs to be.