I haven’t played around with all of Golden Cheetah’s models, but I used it solidly for the past year and I’ve come to the personal conclusion that the CP model is not consistent, reliable, or repeatable. YMMV.
And yes, WKO4’s model is black box and proprietary. Which is not ideal because we don’t know how it works, but it’s consistently been the most accurate when it has good data.
@trianta Yeah, I’m on a quest to find this out too. In other works, “what happens during Dirty Kanza 200?” so to speak. It’s sounds like you’re a Golden Cheetah guy, and that’s cool. So forgive the WKO reference here (because I can’t be bothered to care about the differences between to two, I just want to understand some physiology), is what you and I are looking for what WKO is trying to get at with their “Stamina” metrics?
(this might be off-topic for this thread, happy to take it elsewhere)
the thing is -if I’m not mistaken- that it (GC) has a variety of models to chose from, but I am not an expert to judge them (and it seems even experts have a hard time on agreeing on things)
I can imagine how WKO4 may take advantage of the actual athlete data they have in Training Peaks, so it is quite possible that you’re right then
GC vs WKO4 is definitely a competition to watch (soon the former will also have a planning function too)
Perhaps we’ll agree that GC is the least user friendly then 
Have you done any long events? Because models are just that, and as you probably know, or might guess, that means sometimes a model will accurately predicate outcomes and sometimes it will not. I have an engineering degree and have been involved with modeling other stuff my entire adult life, wish I had more time to play around with this stuff. My WKO4 trial expires soon, and Golden Cheetah user experience is a hot mess. I’m pretty good around software and while WKO4 is better than GC, its not user friendly but at least there is a stack of YouTube videos if you are willing to invest the time.
Yes, I like them.
How much time? I’m kind of lazy.
I’ve probably watched at least 10 hours worth of webinars and probably double that just messing around in the app, and I would say I just turned the corner on getting what I want out of the product.
Truly marginal gains.
Hahahahha…well played!!
@stevemz said “steep learning curve” and “solid 6 months of time” above: The Myth of FTP - #23 by stevemz
The “problem” with WKO4 is that to use it’s full power, you pretty quickly run into the fact you actually need to have some serious coaching skills to understand what is going on and put it to effective use. It is like a sophisticated software tool for analyzing race car performance data. An engineer can look at the data and then build a faster car, retest and repeat. But just buying the software does not make you an engineer 
There are fundamentals of power-based training, and then there are the details and science behind the training.
Lactate threshold is an inflection point in your blood lactate level; riding at higher power than your lactate threshold causes the lactate in your blood to spike beyond your ability to process it, and riding below your lactate threshold lets your body process lactate as fast or almost as fast as it is produced. It is interesting because this blood lactate level corresponds to time-to-exhaustion; at a power below this, you can ride for quite a long time, and at power above this, your time is extremely limited. When you are riding at your lactate threshold, blood lactate levels are still growing, trending toward exhaustion, and on average after about an hour you will exhaust. But note that there is no duration in the definition of lactate threshold; you might exhaust at that power in 40 minutes, or 70.
In some studies, lactate threshold is defined as a specific quantity of lactate in the blood (4 mmol/l), which muddies the water even further because it ignores individual variation in how much lactate a person can tolerate while processing as much as is generated (c.f. the lactate threshold test @Jonathan did). Also confusing things, maximal lactate steady state power is the power you can hold for a long duration with a steady blood lactate level. It is highly correlated with lactate threshold, but testing MLSS directly involves a series of steady state tests (duration of 30 minutes per test) over a few days, which is different from the ramp testing involved in lactate threshold testing. In the study I found comparing them, there is no statistical difference (although MLSS is still a few watts higher than LT).
FTP is a functional (read: practical) way to estimate threshold power. It is defined specifically as the power you can hold for 60 minutes. If your time-to-exhaustion at lactate threshold is longer than an hour, however, then your FTP will be higher than your power at LT. It can also be referred to as CP60, literally the maximum power you can hold for 60 minutes. On average, CP60 is 95% of CP20 (the maximum power you can hold for 20 minutes), but individuals vary. TrainerRoad has, to my knowledge, always recognized this and encouraged people to adjust their FTP after a 20-minute FTP test if intervals weren’t hard enough or were too hard.
So… FTP is a decent estimate of LT, LT is very close to MLSS, and LT and/or MLSS are extremely useful anchors for training intensity. The ramp test and CP20 are decent estimates of FTP, and there are a lot of opportunities to “adjust FTP to taste;” sweet spot intervals are a good way to judge if your tested FTP is too high or too low.
@matthew.weigel thank you!
I think that for very long events these models mostly break down because of all sorts of fatigue (there something like a dozen theories concerning fatigue).
My events are not races per se but have control points and time limits to go through them, and they typically range from 200 to 1000 KM. AFAIK the biggest obstacles are things like saddle sores, sleep deprivation, and being able to ride up the 7th steep, long climb at a reasonable rate.
I know a dozen or so people who are slower than me in any 100-200k distance, but who kick my butt in the longer ones because of, you guessed it, grit.
Didn’t know about the stamina “metric” in WKO4, thanks I’ll check it out
No it’s not. Very few people can hold their FTP for an hour. Attempting to train your aerobic systems based on the power that you can hold for an hour would be a fools errand because at those intensities ‘most people’ are not aerobically limited there, their muscular endurance is the limiter. Coggans puts out a hard hour efforts NP as being a reasonable estimation of FTP, not the definition.
But right below that it also says:
the most direct estimate of your sustainable (threshold) power will be obtained by simply doing a time trial of an hour or so
Like literally the whole rest of my post is talking about the differences between CP60 and LT and how you can’t measure LT with a 60 minute test… but yes Coggan has published things with only his own name attached referring to FTP as CP60.
Feel free to define FTP as LT or as CP60 or CP20*.95 as you like… but don’t expect all three tests to yield exactly the same result. At the same time, I wouldn’t expect huge differences in the results of consistent training using any one of the three numbers as your anchor for defining what easy vs. hard looks like.
yes these are the common interpretations of this science you speak of and is / was based very much on Dr. Coggans past statements and writings. Which is why I was bringing up that article and his comments on that link in my OP. Have you read it?
While you can be super technical regarding FTP, I see it as my tipping point.
Since I bought my powermeter, I am very good at pacing uphill now. If I exceed my FTP, I am going to blow, if I keep under or just on FTP, I will get to the top.
I did. I strongly agree that LT is rarely going to be FTP (haha when this came up in some of the polarized training threads, I argued precisely that, and that the distinction between LT and FTP led to some interesting possible interpretations of how sweet spot work relates to LT and polarized zones).
But what does that mean for training, and getting faster / riding longer / having better results? I think having a practical estimate of my threshold is more valuable than having no estimate, since I’m not going to pay to regularly perform LT testing (and I have enough experience with the imperfections of HR training that I think infrequent LT testing, and going off HR instead of power, is also a step down). And I’m always ready to adjust my FTP based on how workouts are going, so even a bad estimate of LT can be made better just by putting it into practice.
Funny thing is that a relevant “feature request” appeared on the GC google group today. Is this the what you mean by “stamina” in WKO4?
Funny timing. Yes, it seems like they’re trying to get at a similar thing. So the argument is this would be useful for longer events, although they don’t put a hard number or range on “longer”. What it is not designed to address is multi-day endurance events (I think). That seems way more complicated.
WKO4 product manager has a nice way to think about it: you want to move the curve up (increase FTP), but also train to stretch the curve to the right. They are both important.
Even with the same FTP, however, there can be subtle differences between individuals in stamina
- Tim Cusick
@trianta Your friends and their so called grit…grrrrrrrrr 
You must figure out a way to beat them.