I do understand the point that @The_Cog is making, that general fitness is the big piece. However, we are trying to talk about the little things that can make a difference. While a 5wkg rider can beat a 4wkg rider in pretty much any event, what can a 4wkg rider do to beat other guys around the 4wkg mark?
Across my training, and riding with others I see clearly that there is something to this “durability”, repeating & recovering from higher intensity efforts over time versus a flat endurance profile. Like with two workouts at the same IF Percee versus Heseman. Neither is an intimidating workout, but you’d find people who would have a strong preference towards one over the other.
I’d say that for a lot of trained athletes who aren’t able to make large changes to their training while FTP increases might be limited, practicing durability can lead to better race performance even if they are missing 5w from more optimized training adaptation. Though a lot of that is the psychological benefit & fueling is a huge factor in my comfort zone of 4+ hours of gravel or mountain biking. In the mountains that usually means lots of sweet spot and lots of coasting.
When I first saw the new talk about “durability,” I immediately thought they were referring to repeatability, which is something that’s been discussed so many times.
I’m thinking of athletes like Alaphilippe during his '21 road worlds performance when he was able to lay out one attack after another on the final few laps until nobody else could go with him.
It seems like these foundational terms keep getting rebranded to gain new followings and so many people are eager to jump aboard!
I believe that one reason* many view these as separate abilities when they really aren’t is because of the shallow slope of the exercise intensity-duration relationship. It’s a lot easier to detect, say, a 15% increase in time-to-failure than a 2% (<5 W for many people) increase in FTP, even though they are exactly the same thing.
*Of course, the A#1 reason is overestimation of FTP due to 1) use of suboptimal tests, and 2) ego.
I don’t think that “repeatabillity” is a separate property, either.
If you are referring to truly equivalent efforts spaced closely in time, then it is a matter of how quickly you can restore cellular homeostasis, which is entirely dependent upon the exact same processes that help defend cellular homeostasis with increasing exercise intensity.
If you are referring to truly equivalent efforts spaced further apart in time (e.g., throwing down attacks late in a road race), that comes down to essentially the same thing…by being fitter (and/or smarter in how they have raced up to that point), one rider has more glycogen left than another, so appears to have more “repeatability”, when in fact they are just fitter.
“Doing the damn effort” is the only way to answer either question. But, does it really matter?
The model that I developed estimates TTE at FTP, but initially didn’t report it because it isn’t reliable. However, Tim Cusick saw value in it, so here we are.
Personally, I would suggest ignoring TTE, except in the sense of recognizing that 1) the duration that different individuals can sustain maximal metabolic steady state is variable (so that you can’t define FTP as “hour power”), and 2) training just below/right at FTP may maximize long-term progress compared to training somewhat above* (i.e., don’t be overeager).
*Although it is by far from the sole basis for my suggestion, I’m searching for a recent study in which athletes were exposed to an increased training load. IIRC, those who didn’t become too acidotic showed a significant improvement in muscle respiratory capacity, whereas those who did simply stagnated. Ring a bell with anybody?
Speaking mostly as a long-time student of the sport and not as a scientist, I think that the general approach of building fitness gradually is a good idea. Getting that message out there/across, though, could have been done without leaning on a model-derived TTE (although the latter also helps dispel the misconception that FTP is defined as 1 h power).
anecdotally, I have seen some individuals improve tremendously over the long term by focusing on the first approach; and
this would seem to align with Bishop’s hypothesis that generating too many H+ may limit increases in mitochondrial respiratory capacity (as well as that recent overreaching study I mentioned, but can’t yet locate).
I would argue that this slide supports the position of @The_Cog. TTE and its value as a training quantity via historical coaching perspectives is just a method of observation of the physiological “constants” (relative to a single training stimulus time-scale) of FTP and metabolic fitness.
Given one’s FTP will change negligibly from workout to workout, interval to interval, and metabolic fitness slightly more so, but one’s TTE can change much more significantly and is influenced by many more factors (motivation, hydration/nutrition, ability to follow instructions/pacing); threshold training progression as a function of TTE, rather than of the number FTP is set at (within reason), will be more relevant for the scale of a single training block.
This is exactly what I find the best approach to be. If we’re not working vo2max properly or anaerobic capacity of some sort, riding >FTP to improve FTP is so much more fatigue than improvement. At a certain state of trainedness it stops raising FTP anyway so you’ve either got to push the time out or bring the ceiling up. And once well trained, doing the latter seems to not work nearly as well without having done the former. Again, all old news.
Here’s a “durability” progression for a pro male I’ve been working with:
There’s not much to it: ride a lot, do longer/more threshold intervals, do all kinds of efforts throughout a ride, sometimes ride long and race at the end.
Do we have a way of separating endurance from durability? A friend of mine is an ultra runner who started running circa 2007, with races generally ranging from 50 miles to 24 hours non-stop, and he pretty much runs 10 minute miles without ever slowing down (unless we’re talking about trail or other off-road courses since then you have significant hills and footing/traction situations). That said, despite his endurance, running a sub-7 minute/mile marathon would kill him. Does he have endurance but not durability? Or does he have durability but only for ultra-endurance? Curious where, as a spectrum of athletic development, dividing lines occur.
With respect to sub and threshold work, is there any data involving a mixture of primarily sub/threshold with secondary supra-threshold? E.g. 30 minutes non-stop with 10 minutes at 97.5%, 8 minutes at 100%, 6 minutes at 102.5%, 4 minutes at 105%, 2 minutes at 107.5%, thus 18 minutes at or under FTP and 12 minutes only slightly over, for 30 minutes total. Not counting 2 minutes at 107.5%, much of the supra amount (102.5% and 105%) overlaps with day to day FTP variability as well as the imprecise nature of its original measurement. Interestingly, when I do a ride like this, I find the initial time periods, despite the lower power requirement, to be more difficult than much of the latter portion, presumably because the legs need a bit of effort to fully “warm up” (same phenomenon with strength training - the warm up weight lifts are more painful than the actual working lifts despite the significant difference in weight).
We have the Coggan Power Chart, which shows peak values for 5”, 1’, 5’, and FTP and adequate testing protocols for these numbers. We also have a couple of TTE models that attempt to go a step beyond this and allow some real time guesstimates based on historical data. I think the real story is perhaps a standardized quantification and testing protocol of what we have all known to be the biggest factor in winning, which is ability to crank the watts up at the end of a race. Endurance, stamina, durability, whatever you want to call it. Testing FTP at different levels of fatigue (hours, kJs, tss) certainly works here, but at a time when most people don’t want to even do a proper FTP test, what are the chances they want to repeat a test every 1000 kJ for 4000 kJ or every hour for 4-5 hours? The average TR user with less than 6 hours to train per week is just simply not interested, and this metric has no value unless they plan on doing races lasting longer than a couple of hours. This has huge value for elite riders, but they are already doing this in some form, even if it’s not standardized between riders, coaches, or teams.
Again, I don’t see how that is a distinct entity. Fatigue resistance during endurance exercise is fatigue resistance, regardless of how you attempt to quantify it.
In the vein of “extraordinary claims require extraordinary evidence”, what physiological properties could explain differences in “durability” between athletes that wouldn’t also contribute to differences in maximal metabolic steady state power (a.k.a., FTP)?** What is the evidence that any such differences 1) actually exist, and 2) actually contribute to differences in “durability”? Most importantly (since this is not a question related to health or longevity), why might it even matter in the first place? That is, if such questions were answered and “durability” were proven to be the “new must-know metric in pro cycling. . . now seen as the defining marker of monument champions and grand tour greats” (to quote Jim Cotton’s breathless article on Velo…as if it is somehow a new idea that long races are largely a battle of attrition?), what would one do with that information? How would it influence the training practices of those who, e.g., race the Spring Classics?
At least we’re no longer talking about how CLMs are going to revolutionize training for endurance sports…
**The funny thing is, I can actually think of several potential adaptations, none of which I have seen suggested by those championing the concept of “durability”.
This all feels so mechanistic. I understand that in broad strokes and by any evidentiary model this is how we define things, but it feels a bit reducto ad absurdum.
In a purely mechanistic simple model as long as fuel is flowing the machine keeps working. Keep the flow at ‘steady state’ it should run forever.
If we complicate the model and talk about physical strain there is a duty cycle to the machine based upon the ‘durability’. Assuming everyone has the exact same machine, we could then sort of statistically say it all comes out in the wash. More machines, the longer the system functions.
Add more complication in secondary artifacts, like different fiber types, crossover fiber types, ‘fitness for purpose’ and you can start to tease out the ‘specificity matters’ into the model.
Add in tertiary tendon and flexibility, blood plasma, cooling, hydration, repair, nutrient availability and the effects on the hormonal system, stress responses and how say elevated cortisol effects performance both physically and psychologically. I think most people know that generally your mind is going to stop you well before your body has to. ‘generally’.
I think I’d call it resilience anyway, not durability. I don’t know, I’m sure I’m full of and I’ll get smacked down shortly. Like some flat-earther saying, but I ‘feel’ like it’s flat, you know…
Now more coffee.
edit
Okay 20ozs of Kenyan Mukurwe AA in front of me…
I guess I can see that for what I guess I’d call metabolic training given a peak vo2max fitness the best bet for this ‘durability’ could well simply translate to raising ftp. If a rising tide lifts all ships (and each ship is a mitochondrion) then having more ships reduces load per ship. man this coffee is good. (it’s just coffee I promise).
So if I’m following, something like the following argument:
Fatigue resistance = having more glycogen remaining at the end of a long event so you can push higher watts in the decisive moments that are required to win
Having more glycogen available at the end of an event is enabled by using more fat for fuel during the earlier part of an event (eating carbs also plays a role obviously)
Being better able to use fat for fuel also correlates strongly with maximal metabolic steady state power
So someone with high FTP (measured correctly) also has high fatigue resistance
This conceptually right? More to it than this? Maybe also ability to clear lactate/H+?
and I’ll get smacked down shortly. Like some flat-earther saying, but I ‘feel’ like it’s flat, you know… 
