Why Riding Slower Makes You Faster [GCN's latest video] Thoughts?

Also if Zone 2 is 55-75% of FTP, does 1 hour at say 70% give more benefit than 1 hour at 55%?

Not by percentage but by feel to stay under LT. Under LT beneficial time not intensity. So you will get far more adaptations through time on your bike not by intensity of your rides. There is also fatigue component. If there is no significant benefits between your example intensities why put more fatigue.

And for fat oxidation - riding in your fatmax does not improve your fatmax. Time in lower zones improve fatmax - so another case when volume is the king. If you take too literally those beneftis charts, we should ride threshold and vo2 max all the time. Good luck :slight_smile:

My personal experience is - since added z2 to my intensity, I am better on the bike in every way. I clear lactate better, my endurance improved and my short power improved. I can recover better after hard efforts and ride longer and improved my volume consistency. There is no shortcuts and magical things. The more you ride, the better you get. With that you have to lower intensity to improve recovery. With better recovery, comes better feeling on the bike and ability to introduce more stress during training, so you can ride more. And circle closes.


Take a look at your graph. PA FATox (diamonds) around 275W. Not the peek. Close to the peek, but not the peek. What is special about 275W? It is roughly the average that ISM finds for Zone 2 in the PA cohort. We know these same athletes have at 400W FTP (generally, on average). (numbers taken from the same paper you found your graph…metabolic flexibility ISM et al.).

So at this point, most folks do some sort of “FTP math”. So 275/400 is this or that intensity factor. They then take that percentage and apply it to their (possibly sensible) FTP number. Don’t do that. It’s an impedance mismatch. It makes no sense.

Now look at squares. The first thing to do with those athletes isn’t to pick out the peek. It’s to flatten the curve. 200-235W. Get that area up. Riding in an area higher intensity than that doesn’t “nullify” anything. That term is ill-defined anyway. Things don’t happen to your body and then suddenly they didn’t happen. So how to lift that 200-235W part of the graph (or whatever your numbers are). It sparks a fair bit of debate but most ppl think doing hours and hours of riding in that area is necessary.

ISM Zone 2 is most definitely a form of stress. And as such, it isn’t “max fax ox, min lactate”. That would be Zone 1 (ONE!). There is a Zone 1. He didn’t start counting his zones at number two. LOL. He started with one.

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@Crosshair You’ve mentioned a few times about averaging power across a workout to understand the training impact, but i’m not sure it works like that. Do you have any reasoning for it?

I would think that a VO2 workout that averages out to .7IF would be very different from staight Z2 at .7IF, right? Taking it to a logical extreme, I could just average the time spent at 0watts pre/post workout and have all my training be in Z1…?

Isn’t the training impact really from time in zone, not average power?



I feel that bringing in NP, TSS e.t.c, is just confusing the thread, what we are looking for in the Z2 (and this is similar to the recent thread on Vo2) is a metabolic response from doing the workout at a certain HR, Power is a output from the work that the body is doing, and is not reflective of the metabolic changes that are happening in the body, so you can’t say, my NP was X, the metabolic changes from this was Y, and I think that is where you are confusing people, as in, I can’t see a link between the two, why are you bringing it up

Just my opinion, as I feel torn between disagreeing and agreeing with you

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My understanding is that the advantage of Zone 2 training is obtaining the metabolic benefits at minimal cost of stress, allowing much higher volume than you would be able to tolerate at sweetspot or above. I have to chuckle at Coach Chad’s assertion that you can repeat sweet spot day after day because it isn’t that stressful. For us “senior” athletes, that much intensity is not tolerable.


So I rediscovered this TR blog post after going through this thread. I think it holds up really well / is accurate even in light of what ISM is advocating.

The new, new part, for me here, is that you have to be really diligent about your Z2 work. It’s not just “time in zone.” And if it’s not a separate workout, then do it as part of an extended warmup.


You always use carbs. In zone 2 actually quite a lot, even when highly trained with a well developed fat ox engine.


This is all quite interesting stuff and makes me wonder if this is why I haven’t improved as much as I thought I should have given the amount of cycling I’ve put in - most of which is at high intensity (sweetspot upwards).

Planning to change my routine so that my Sunday ride is a slower one, mostly Z2, might even keep this indoors for a good chunk of autumn / winter and also going to try and add 1.5 hours (2 sessions) of Z2 in the week (more if I can manage with work / family which are both pretty full on). Will also try and keep some of the high intensity sessions (VO2Max / Threshold) in if I can,

Hopefully about 4 hours a week of endurance… does this seem enough to see some changes in a few weeks?

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That’s a HUGE range. Maybe chemically in a lab that is all in the same zone but I think that is a good question. Is 55% as good as 75%? Is all Zone 2 equal?

Maybe its worth mixing it up - some at 60%, some at 70%… I’m sure FTP varies somewhat day to day as well so makes sense to keep towards the middle?


I might feel same (and also think that some of my tri training added to that even when trading bike sessions for that).

What I’m asking myself is: Are those lactate clearance benefits of long z2 the same lactate clearance benefits that over/under workouts target? Do both target same underlying physiological adaptations?
(Would really like @empiricalcycling or @kurt.braeckel or @brendanhousler commenting on that…)

I really like those more spiked (~120/85-90%) o/u and think these are great complements.

Edit: I guess o/u only gets you so far and at a certain point you have to put in the time for long z2 volume.
Coincidentally and alongside ISMs points I made my own workout some time ago combining z2 before o/u.

If I want longer z2 I just do easy resistance mode through first o/u block. If I’m short on time or don’t want all that intensity I skip second o/u block.

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If you want a slightly narrower target, I saw 70 to 80% of your observed max heart range as a target in one of the videos above.

great question! those guys above will know this one better than me! they are much more qualified.
but my understanding was that the over under work on our maximal clearing rate during the under, whereas the endurance is just constantly consuming much smaller amounts of lactate, but that still helps with us becoming more efficient. also maybe the interconversion of muscle fiber types from the long ride also aids in this (?!)

all i know is that they both work wonders! :rocket::rocket:


All aerobic training is lactate clearance training since lactate oxidation needs transporters, mitochondria, and oxygen.

Over/unders either work similarly to endurance rides in that there’s general aerobic adaptation happening but in increasingly larger motor units due to fatigue, or because of the increased lactate presence they may increase mitochondrial lactate transporter density.

Quick note here to add to a previous post, I just did two podcasts with Andy Coggan, and we discussed isotope tracer studies and that the “lactate shuttle” as ISM understands it is a bit of a misinterpretation the way Andy (and I) interpret those data. So do fast twitch fibers create lactate and slow twitch ones oxidize them? That seems to be the only way Brooks and ISM think about it, but fast twitch fibers can actually be highly oxidative and burn large amounts of lactate (both their own and imported from the bloodstream) and also fats. Watts Doc #37: Your Fast Twitch Fibers Probably As Aerobic As Your Slow Twitch - Empirical Cycling goes into a study looking at the oxidative capacity of fast twitch fibers.


Almost certainly not, but if you buy that duration trumps intensity at those relatively low aerobic outputs (and I certainly do!), then sustaining 5 hours at 55% is far less fatiguing that 5 hours at 75%, and that matters. Inigo San Milan pushes a lot of riding at/near LT1, for which a crude proxy might be around 72% of FTP (let’s say). Even he would say “don’t do all your endurance riding at LT1.” Almost all of it should be below (and probably well below) LT1, as you no doubt know.

I do a lot of this. Start with long rides extending duration out to whatever (5, 6, more?, hours), keeping intensity steady in that .55-.65IF range. Then you can start adding in time at .65-.7 or so as you go. I love progressive endurance rides, start low, hit “LT1” or even tempo by the end of a 3+ hour ride. Brilliant, especially if you’re time crunched, IMO.

I am absolutely flattered that you would lump me in with Kolie and Brendan. I’m not academically in Kolie’s country code, nor athletically in Brendan’s and both are much more experienced coaches than I am. But my feeling on this is that recovery is an aerobic process. The ability to process lactate to get NADH into the electron transport chain is something that is worked whether you’re doing long rides or over/unders. In one case, you’re feeling the “burn” of the acidity associated with lactate production because you’re doing quite a bit of work anaerobically, thus you process a lot of lactate in a short period of time; in the other, you don’t have the burn, but you’re still processing lactate, just less of it over a much longer duration. The longer you ride, the more aerobic adaptation you can see, and that helps the recovery process in between your harder efforts.

TL;DR - if you’re looking to train your aerobic energy system and reap all of the physiological benefits (better/faster recovery between efforts being one), long steady endurance riding is the best. I like over/unders for more specific preparation (rather than general preparation), but both train lactate clearance. FWIW, I also favor the higher power/lower power over/unders like you described for road racers (my primary coaching clientele), and I think Brendan uses as well.

All IMO, and I welcome Kolie (or Brendan) to come over the top and tell me I’m a moron for my exceedingly crude understanding and description.

Correction: Kolie is much more qualified; I am not. :laughing:


Thanks a lot to all of you taking the time to answer my question :pray: @kurt.braeckel @brendanhousler @empiricalcycling … long time subscriber of the empirical cycling podcast … obviously I will re-listen that episode.


No scientific background and any arguments other than personal experience - for me no. Example - 8h/wk 3xFTP/O/U - my FTP was improved but my overall endurance was way worse than Z2 with 2xFTP/O/U. O/U was best example of this - I was wiped completely by them till I have introduced Z2 - suddenly they become way more managable. The same is for me and VO2 max - without bigger volume and Z2 rides, vo2 max block was horrible. Afher that I was tolerating those hard efforts significantly better and was pushing way more power. I had the same experience when I was returned to training after month off .

Like I said - this is only personal experience and observations from 3 years of training. I do not have any arguments for and against - just what worked for me.


I was a little sceptical as to removing intensity and replacing with Z2…until I started riding Z2 with far more intent i.e. zero coasting, producing as much TiZ as possible at 70-75% IF. After a few hours I find these are HARD. Not just physically but mentally keeping constant meaningful power through the pedals on undulating terrain.

Compare this to the 4 hour ‘endurance’ rides I used to do with mates where you spend the majority of time in Z1 and merely the Z3/4 efforts up hills dragging the average up into Z2 - completely different rides. Unequivocally, my durability and fitness improved doing the former.


They arent the same in your example though, there is ~7% difference.

Plus who is saying they are superior?

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