For me, the minimum effective dose of z2 is a ride that is longer than my current (consistently executed) z2 maintenance ride. For me, that is 2hrs so my minimum effective dose currently is 2.5hrs which I am working into my weekly schedule with my long ride 3hrs+. In time my minimum effective dose will be become 2.5hrs and so it continues…
Alas, like most I will eventually become limited by time and will have to manipulate the volume/ intensity equation a different way.
I know we are all different, but 82% of maxhr seems really high for ‘low intensity’. Have you tried bringing that down to 70% or less? I bet you’d be able to handle a lot more volume and recover better and not have to eat as much of a carb rich diet.
You mentioned life constraints, so maybe this works well for you if that’s the max hours you can do anyway. Just an observation.
From my own experience in running, once I brought my easy pace down to way lower than I ‘liked running’, I was able to put more hours in and do intervals harder. I went from an 18min. 5km guy to a 16min. 5k in 6 months. It has worked well for me on the bike to with this approach, but I find it harder to stay disciplined with group rides and such.
6g/kg is at the bottom of moderate intake, and low for endurance athletes! It is really easy to search and find the recommendations. For example TR has a blog post, and TR focuses on time crunched, and that post aligns with all the other recommendations at 6-10g/kg.
As to your other point about bringing average HR down to 70% HRmax. Yes, I’ve experimented quite a bit. Like my coach said, my engine is my engine. Average HR for a double century at .67 IF was 74% HRmax. And days before that I set an all-time 1-min power pr that was recently matched, and a few days after the double century I set a Strava KOM at 52 seconds that still stands today. I rode strong into that double, and rode strong immediately after.
In late 2019 and late 2020 when I tried riding around at lower power (closer to 70% HRmax) for months and months, it just made me slower 
Pushing up into what my coach calls ‘true endurance’ made me faster. I’m doing these on feel, but its usually 66-75% FTP with a negative split on the ride. And average HR comes out 78-81% HRmax and 84-88% LTHR. My LTHR is 92% HRmax, so I have a narrow or compressed HR range compared to others. Not that its correlated, we don’t know, but after a year of switching to doing these ‘harder’ easy 
rides, I also saw a big drop in RHR and increase in HRV (back to normal levels for my age). YMMV and all that.
Per Coggan and Friel I don’t use % HRmax, I use % LTHR.
Depends on what you consider z2… but coming off of some serious inactivity in the peak of covid i still was doing 80% of my work below my first inflection on my lactate curve or level one described in the image below. And 10% in level 2. Avg weekly time was only in the 6-8 hr a week. Using that now to maintain what fitness i have while just trying to build volume through consistency gains. Im only 10 watts off of my peak from last summer. The big thing i noticed was that general fitness is there, but fitness above z2 needed to be gradually built. Tte definitely tanked without doing a proper amount of intensity.
For my purposes I treat LT1 as top of my Z2 range.
My Z2 is between the actual point of inflection (AeT) and what I call my LT1 (about 25W >AeT
I think we’re describing the same ballpark as we ride Z2 as the range it should be. When out during these type of rides I use my breathing and the alphabet test to assess where I am at on the scale. You can feel the boundary.
ISM Z2 is in the same ball park as Friel Zone 2 I guess? But where to ride, for me it depends on weekly volume. For me, since december I tried to do weekly volumes between 12-15h (before it was 10-13h). One intensity session a week (zwift race) and shorter endurance rides at a higher Z2 level. For longer or when little fatigue dropping in I use normal Z2.
In intervals.icu I made my own zones. Z2 is normal endurance, Z3 is my endurance+.
Time spend from 4th December:
End of the week I will receive my Lactate Pro so I will assest some home lactate testing to see where my LT1 is. As a century or granfondo rider my primary goal is to become more aerobic. So bigger base and shift LT1 to the right.
I myself have used lt1 to mean the range from inflection to +1 mmol, but even in the graphic i posted it listed the first inflection as lt1. However it did use the same ballpark range we are all talking about as z2.
In the context of this thread, i do not follow an ism training model since i try to spend the vast majority of time in z1 and trend towards z3, z4 and z5 as intensity targets and just use some z2 work as variety of my endurance training. I have noticed threshold work moves the needle of changing the slope of my lactate curve while z2 just moves it to the right. When i do enough volume of z1, that also shifts the curve to the right so that’s why im tending toward intensity that is more specific to my events of short and middle distance tris.
On the curve above ,LT2 just looks like a random point on a straight line!
Yes I think so too, well not random, it is just the generic 4 mmol by the look of it, so wouldnt take any notice of that point on the graph.
LT2 is supposed to be MLSS, a “steady state.” You are correct, it doesn’t look at all steady on that graph, just the point where 4mmol is, but no evidence that this is actually MLSS for the test subject.
The thing is, if your exertion goes above MLSS, the steady state will quickly fall apart. I think it is very difficult to capture that entire curve in a single test, because there needs to be appreciable time (5-10 min) between steps for lactate to stabilize, and the wattage steps need to be large enough to get you from resting all the way up to north of MLSS. What makes more sense is to do a first “coarse” test covering the entire curve with fairly large wattage steps (e.g., 25-30w), and then go back and do separate finer tests (steps of 5-10w), one just targeting LT2, and the other optionally targeting LT1. The idea would be that for LT2, you could start a little below where you think it is, and progress very slowly with little change in lactate, until you go over MLSS and then boom, LT rises a lot.
If you think about doing two or three tests like this (depending on whether you want to drill down for both LT1 and LT2, or just LT2), on three separate occasions, it would get pretty uneconomical for any commercial service to offer. So the “standard” is just does a one-time test which is basically a Rorschach blot. People with a home testing kit are not limited to this.
Has anyone read ISM’s PDF called “The Scientific Preparation and Monitoring of the Elite Athlete”? Lots of great info. His zones are clearly defined, but you can’t use his system with power-only measurements. I’m pretty confident I can get very close with power and lactate measurements, though.
When everyone has reliable lactate and breath data at home, we can finally have some nuanced discussions.
Metabolic Map
Comparison:
Zones:
Monitoring:
That is how i felt when trying to visually eyeball lt2, but when i entered my data in to one of the free online curve analyzers the results were pretty good. The key is to have 2 points above lt2, but i am not sure how to do that without having the last point just being until failure and not worry about it being the full 5 or 8 minutes in the protocol since your purposely finding a point where you are no longer in equilibrium.
Which one do you suggest?
Did you previously perhaps do Z2 mixed with Z4-5 as the intensity targets, and if so have you seen any difference after moving to mostly Z1 but possibly integrating quite some Z3 in there? Perhaps a reduction of VLaMax, so becoming more of a tempo (LD triathlete) physiology?
For the most part, yes. I have an inherently moderate vlamax… not high enough to be a sprinter, too high to excel at threshold work. Avoiding tge middle zone and doing z2, z4, z5 (more 5 than 4) made threshold efforts completely miserable and running off the bike was really affected.
So there were two different adjustments i made… first was doing more z1 and controlling z2. This allowed better compliance and volume so my curve moved to the right, but percent of ftp for z2 didnt really move. I’ve since been favoring more z1 as my “go to” endurance pace… for me that is staying below 70% of ftp or 120 bpm. The second change was adding more middle zone at 85-95% of ftp. Those blocks lowered lactate at those power targets more than you’d expect from a shift to the right of my curve. Im not doing full lactate profiles as often these days, but mostly spot checking after 20 minute intervals. Z3/lower z4.
Racing last year was ok… i didn’t have my fitness that i had pre-covid, but my overall volume wasnt what it used to be so that was expected. Racing though was far more predictable and the warmed over death feeling after the first hard effort was no longer there. Running off the bike was much closer to predicted pace.
So tl:dr… yes, for me working the middle zones seems to have more of an effect on substrate utilization. (ISM has said z2 increases lactate metabolism and fatty acid oxidation at similar rates)
who’s graphics are these? specifically the first one
Those are straight from an ISM presentation from like 2012-2013. You can find the PDF online quite easily.
