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In the context of the article I don’t believe it matters. The point of that table is that years of high volume zone2 training results in greatly improved lactate clearance.
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Agree. But he waffles on that a bit. I listened to multiple podcasts to see if he made a firm statement. Seems he is clear that 3 min steps is not good. But sometimes indicates 5 is OK. Then maybe 7 would be better. 10 does seem to be what he would prefer.
I have pretty good data using 5 min steps. Am going to try 10 next go around and see if it is any better. For lactate step testing to define LT1
Lt2, MLSS, etc are another kettle of fishes. I’ve come to think LT2 is not worth talking about as its so hard to define from data.
The take home is the important part and also agree with Brian - a lot of riding in and around LT1, without even worrying about the precise number, is very valuable. It just works. But it’s not exciting and not amenable to 45-60 min workouts. But if you want to really get good at riding a bike for longer durations at higher wattages, just do it.
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Absolutely Mark, slow rolling in zone2 is not exciting and the results come slowly but definitely worth it.
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Good article. Thank you.
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I would say its more so that LT2 is just so hard to define that it’s not something that he’s going to really focus on. His main key, seems to be that the best athletes have high fat burning capabilities AND high lactate consuming capabilities and that this is optimized through training right at LT1, or high Z2 in a 5 zone model.
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I thought his other point is that attempting to define LT2 is pointless, you are better off identifying key efforts (like a decisive climb) and using lactate to measure progress on efforts at those target durations. Along the lines of critical power terminology, he suggest an 8 minute decisive climb has a CP-8 power (or PDC-8) and LT-8 lactate. And using LT-8 as another measure of progress.
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I’ve never really paid much attention to this chart in i.icu. Really describes it pretty well. With the pandemic full into “happy hard” no man’s land. And after the TdF more refined with plenty of time at LT1 (which is full in tempo power zone for me).
138bpm is my LT1 heart rate. Training volume was pretty much constant in all the years (18-20h).
However, 2017 was a very strong racing season. Across the board in 3 to 12h events. My high end (5min power) was much higher. Interestingly, I never did any vo2max work in 2017. This started in 2018 when I tried polarized. In 2017 I did plenty of threshold (sst & actual threshold).
I guess the main reason for the successfull 2017 season was weight. I was not much lighter but sufficient to make a difference when there is a lot of vertical. And in my races there is always a lot of vertical. Haven’t gotten to that race weight again since then. I tried but failed.
Only had one true race in 2020. A 5h race. Data showed that I had collected so much time at threshold as never before. This was interesting to note because I only rode tempo/no man’s land for most of the season (of course, taking into account how I felt). Almost no threshold or above.
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The length of stages has not been clearly specified in any of the interviews.
I think the preferred length is 10 minutes per stage.
In the Scientific Triathlon podcast, San Millan was asked about lactate production vs.
lactate utilization in his test protocol, but the question was not answered.
You can have “low” lactate value because either
a) you produce little lactate
b) you have high clearing ability (ie, you produce more, but you also utilize more)
The question about how lactate clearance / production is measured using his protocol
was never answered.
Similar testing protocol has been used by the Norwegian triathlon team.
Arild Tveiten has explained the protocol in some of his interviews.
One of the consequences of longer stages (in a testing protocol) is that
the “anaerobic threshold” will be at much lower lactate values than you would
have at shorter stages. The threshold can obviously be determined in tens of
different ways. But, it would not be uncommon to see “anaerobic threshold” occurring
at values of around 2.5mmol/L when measured using long stages. This implies that
if you measure your threshold using short stages, your threshold is probably too high
and that you train too hard.
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I’ll look for that - thanks.
Expect ISM is looking at more than a steady value by using ten minute steps and not just calculating LT1.
Definitely like the concepts he puts forward and have found value in spending more time at and near LT1 for my own training.
The reason for long stages is that in short stages (say, 1-3 minutes)
you don’t know which stage (intensity) lactate is coming from.
In a 10-minute test stage you know that all lactate was produced in
that stage.
Understand that but thanks.
To avoid derailing the ISM thread on methods, we have discussed lactate testing protocols and some forum members have posted results in this thread. Have a look and do feel free to comment or add more data if you like:
Here is some info from David T on how that chart is constructed:
Each ride has a power vs HR curve created by breaking the ride up into 1 minute segments, adjusting for HR lag and calculating average power and HR for each segments. These are the data points used for the decoupling related charts on the activity power page. Only segments with 100% moving time are kept.
The traces for the comparison chart are created by bucketing the power-HR segments for all matching activities into power buckets and averaging the HR.
Forum post: New compare page with power vs HR chart - #64 by david - Announcements - Intervals.icu Forum
Here is a chart showing my current z2-z3 border (7 zone model: endurance-tempo) and comparison to previous years:
notes, starting from left curve to right:
- 2019 was a year with detraining from May-August, followed by TR traditional base 1 and 2 and finishing with an attempt at polarized. Laid the foundation for 2020.
- 2018 was a mix of TR SSB early in the year, with outdoor riding and a short block of TR’s traditional base in Sept/Oct
- 2020 transitioned to more aerobic development
- 2021 continued the aerobic development
- 2017 was peak fitness with a lot of work in middle zone and anaerobic capacity, starts diverging from 2020-2021 around 82% HRmax
Will be interesting to compare once a full year of 2021 data is available.
I’ve just done my own heart rate vs power analysis. What I wanted to look into is how my LT1 heart rate vs power differs for the first two hours of ride vs the second half. Drift is not considered in the respective i.icu plot (I guess).
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I like that chart, but probably because my improvements are super obvious, although it gets super messy close to threshold with the inclusion of shorter VO2max intervals that drift through the threshold hr range.
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Nice pay off!
I’m pleased that averaging close to 8 hours/week has delivered results. Mine looks better if I remove some years and don’t screen grab the short interval noise above threshold:
- 2018 threshold training approach (TR)
- 2019 detraining and curve moves to the left
- 2021 after a year of “ISM-like” zone2 training approach (FC)
2021 is a small improvement on 2020, and either year would have shown a solid shift to the right.
And comparing 2021 to 2017:
I’m pretty confident that by the end of year my coach will get me to surpassing my previous best year.
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You could be a posterboy for your coach with these improvements 
Just stumbled across this paragraph from one of Andy Jones’ papers on critical power
Decided to plug in my own numbers (CP 345w, 6min power 400w), which gave me an estimated LT of 290w… which is very close to what i’ve been seeing with my dfa-a1 testing.
Probably makes a good rule of thumb for those without lactate or HRV testing to nail down that ISM zone 2 power
New ISM interview on FastTalk about the race season.
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My figures are 6min - 280W CP-. 230W which would put my LT1 then at 180W. Xert LTP has me at 183W and my DFA/A1 is around 185W. So it’s basically as accurate as the other methods at least for me then.
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