It is fun to discuss!
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Itâs your list so modify last bullet point (perhaps with some criteria) if you want. It is only straightforward if you know what youâre looking for. What would you need to look for as a relatively inexperienced self-coached athlete a few years ago to get it? Thatâs what I mean by criteria.
I would add âMoxy may or may not identify LT1â and âBreath count may or may not identify LT1â (I think that was carytb point aboveâŚbreath count not same as talk test)
Like you have done in the list, using term âLT1â informally. Hoping no one starts up with âbut gas isnât lactate, or HRV isnât lactate, so using wrong termsâ. Disambiguating constantly is too much.
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Rr is so easy these days since cadence is measured by your garmin.
How many revolutions for 1 full breath? And you know rpm.
6 in, 6 out at 90 rpm is 15 breaths/min
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I have all the gadgets, so Iâm a little biased.
Moxy doesnât really help find lower threshold based on my experience with three Moxys. It may help find upper threshold if you use one Moxy on a non-working muscle.
Data from a metabolic cart has been hit or miss for me for lower threshold. Finding the workload for an RER of 1.0 is pretty easy though if thatâs your upper threshold.
Lactate testing for me correlated well with alpha1 of 0.8 for lower threshold.
Xert has my lower threshold right around where I can start to feel a difference in breathing effort.
WKO and Golden Cheetah both give reasonable results given the different foundation for the softwares.
My Garmin watch even has a reasonable FTP.
I found that the feeling of +/-10 watts around lower threshold feels very different. Iâm lucky I guess in that the sensation for me is quite different at those intensities.
All these things line up well for me. I just use a three zone model since I have a good idea of my boundaries.
I typically do a lot of testing every couple months.
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And here is another one for the list, in fact it goes hand in hand with my field testing comment.
A week ago I did 2.5 hours total with 130 minutes at .71 IF and roughly 10 minutes warmup & cooldown:
and this is what Garmin said:
Garmin estimates that by running machine learning (ML) algorithms on HRV, HR, and power-to-HR. And doing some calculations related to EPOC and VO2max.
And zones (per @redlude97 request after I originally posted):
Another recent one at .75 IF
Take out the outliers and traffic stops, its around .74 IF for an hour:
A bit of glycolytic/anaerobic stimulus on that one because at the beginning I didnât do a good job controlling power thru an intersection, and then a little extracurricular above threshold fun around 30 minutes and again near the end of the 100 minutes.
This is Garminâs view:
and zones:
In general those Garmin 530 training benefit summaries have been pretty darn accurate.
And FWIW, Xert has my lower threshold power at 191W which translates to .7 IF.
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LTP represents the lowest possible value for Threshold Power when all Endurance Energy reserves have been depleted.
It has it at 189w for me. And its a bit high. Itâs more like 180w in normal temperature. But I havenât been riding outside in 3 months and the longest indoor ride Iâve done this season is 2h30m
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updated the post for ya
You can see why I use Friel HR zones⌠but some use Coggan, and some use their own zones. From talking to my coach (he has over 50 athletes), HR zones can vary quite a LOT and therefore need to be individualized.
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Interesting. Idk my Ftp at the moment, anywhere from 240-255 I would sayâŚ
Your LTP is 68% of your mFTPâŚIâm at 78%-80%.
This type of rider profiling is key IMOâŚ
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Thatâs not bad, though. Less than 10 watts off and it gives you an idea of where to start âlookingâ for your lower threshold. And thatâs only from power data. I like it.
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The WKO mFTP is 268-269W after a strong push for 32 minutes at 276W where I ran out of road and daylight. So it wasnât a max effort to failure.
Xert LTP is 70% of 272 which is 'what my coach gave me for not going to failure" estimated FTP.
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My curves. Riding a lot. And since Oct 2020 (actually since spring 2020 but I did not have a la device yet) riding a lot @LT1
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Tried this for the first time today. This is a transition/rest week after finishing 16 weeks of building so have been playing around with all sorts of various benchmarks/tests - I have done a ramp test, a 1hr time trial, and now this AeT all within the past 7 days.
Using this method and a cutoff of 0.75, I got a VT1 heart rate of 149.75 bpm, with a fairly wide margin of error mind you. I took the raw data that the HRV app gives you (in a CSV file in dropbox), and plotted DFA alpha1 as a function of HR, fit a linear trend line, then solved for HR value at DFA alpha1 of 0.75:
This is in keeping with the value I would use from RPE, and is also my HR that I can literally sustain for all-day bike rides (longer than 20 hours at a time). I had also done a 1-hour time trial the day before this, and this HR value for VT1 is 83% of my LTHR (based on max 1-hr HR, VT2 HR, and RPE, all of which agree to within 1bpm), and 76% of my max HR.
During the testing protocol, I noticed that changes in on bike position had a significant impact on measured DFA alpha1 (see figure below). Despite only having 1 artifact removed during the whole test, you will note that points A, B, and C below are significant outliers. Point A is when I first switched from the hoods to the drops. Point B is when I read an email on my phone.
Point C is interesting because itâs when I deliberately tried to vary my heart rate significantly by intermittently breathing very slow, then quicker than I needed.
As expected, there is poor correlation as to my power output at this threshold. Within the past week week alone, my power output during an interval at least 10 minutes long that had an average HR of 150 has been anywhere between 201w and 233w. This was true even when you removed the impact of any cardiac drift by solely focusing on intervals within the first hour of a workout, when drift was less than 1%. Major confounding variables here seem to be caffeine intake, time of day, sleep quality the night before, as well as how fatigued I am from recent workouts.
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How about this ?
Of course it will work reliably all the time and produce valid data. Take a look at the power meters. That is the future of any sports data gadget. Something between meh, at least it is consistant and random number generator.
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We were using noninvasive tissue lactate monitoring in pediatric ICU about 10 years ago. I donât recall what mechanism they were using for this at the time, but Iâve always been surprised that we hadnât seen this used in sports wearables yet.
Iâm guessing this company is using some sort of electrochemical biosensor to detect lactate with their product - Biosensors based on electrochemical lactate detection: A comprehensive review - ScienceDirect
My guess is they are taking advantage of the correlation between sweat lactate levels and serum/tissue levels, and actually measuring sweat levels - https://pubs.acs.org/doi/10.1021/acssensors.1c01009
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Reading through I saw this didnât have an answer so hear are my .02
HR staying stable is more or less the oxygen required at the workload is stable and your heart is able to deliver it. Decoupling later in a ride (when itâs not the slow component) I would assume to be that your muscles are requiring more oxygen. Why would that be? I think itâs because as you fatigue you start accessing less aerobically trained motor units to provide the wattage. Less efficient = more oxygen usage.
If by fractional utilization you mean higher % of vo2max at LT1 and LT2. HR is only one variable of cardiac output. Your heart can also increase itâs stroke volume which would deliver more oxygen per pump. Also blood volume contributes to stroke volume; its one of the first things to return after time off and base training. So you could produce more watts at the same heart rate. This could mean your vo2 max has increased but its not a definite. Vo2 max is measured by how much oxygen is USED and not how much oxygen CAN be delivered. Its the reason vo2max is measured higher in XC skiing vs running, then biking, then swimming. More muscles being used means more oxygen demand. Itâs like having a lambo in bumper to bumper traffic.
So when you are increasing your fractional utilization you are increasing your ability to consume that oxygen that is being delivered to your legs. That can be capillary density, thinner/longer muscle fibers?(fuzzy on that bit), type 1 fibers, or more mitochondria density.
So although heart beats and stroke volume are important, more beats or bigger strokes are pointless if oxygen utilization is unchanged.
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Whoa whoa whoa!
Wait no youâre right. 
Although up till recently I wasnât coaching for profit anyway, and never really intend on âmaking a livingâ from it. Itâs a side gig/passion play, and it is fair to say I learn more than Iâve ever given here anyway.
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