Off the top of my head…dehydration, caffeine, acute fatigue, increased cadence, increased respiration rate, using more upper body muscle, increased stress (either life stress or even just riding on a busier street), and heat. I’m sure there’s more. And then there’s other things that can keep your HR low that aren’t increased fitness to further muddy the waters.
We know about heat and hydration, mentioned those already. And also what is “acute fatigue” if not the muscle fiber explanation. Why does it take more blood to deliver the same power when you get tired?
Bottom line is many many coaches use how far and how hard you can ride before your HR starts drifting, and changes in that (all else equal), as being indicators of increased fitness. And remember, coaches often figure out things that work based on careers that are basically 1,000s of experiments even if they are wrong about the “why.” Sometimes they’re ahead of the physiologists in that respect.
So if all these coaches use it, my guess is it probably works to some extent, and the complicating factors you note dont change that even if they do make it more complicated. I don’t think Joe Friel is some kind of crazy outlier here.
Then the question is, if it does work, why does it work. What is it correlated with such that it appears to have value? Otherwise If it has literally zero validity then why does it often appear to work? Or are you saying that all these people are perceiving a pattern where none can exist? Forget about using it to “measure your base” specifically, let’s leave that aside.
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That’s what I was really asking Old: if the explanation isn’t true then why does it seem to work or is it all just noise. I find the latter hard to believe. Curious what he thought about the former. Happy to hear from you also though!
“Many, many coaches”? No one paid any attention to “decoupling” before Friel proposed looking at it about 10-15 y ago (based, apparently, on a misunderstanding of physiology, equating mitochondrial uncoupling to cardiac drift). Since then, it’s simply been follow the leader.
It’s all just noise. Cardiac drift is a long-recognized phenomenon, as is the fact that it is attenuated by training. The leap of faith is equating absence of drift as completion of “base”, but given that no one can even explicitly define what the latter is, well, hopefully people can see the problem.
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Interesting. So you are saying it is just noise, that Friel and those who follow are not actually seeing anything at all, because there’s nothing there to see. Wouldn’t be the first time.
If so, fine, and that interesting. Good to hear these views! I’m not trying to be argumentative, just trying to figure out what you’re saying. You have this way of pointing out the weakest part of someone else’s statement and when the weakest part is tangential, it’s hard to know what you think the conclusion is.
As I said, I’m trying to ignore the part about completing base. Is it an indicator of fitness or is it not. Sounds like you think it’s not, Just noise, and that’s helpful.
Sorry, our replies keep crossing 
Okay @Captain_Doughnutman gave you the technical answer here is a layman’s way of looking at it.
Let’s say you go out for a hard ride with very little base (but you’ve got fresh legs and you’re reasonably athletic), you might do well on the first ride and think I’ve got this, but over a short number of weeks you’ll burn out from continuous hard rides cause your body isn’t used to dealing with the repeated load. You’ll quickly loath the next ride cause you’re worn down, tired, grumpy. sore and generally miserable to be around. This a big subjective cause some people can handle more load than others.
Now if you have a solid base, you go for that same ride and you’re able to go for that ride and your body can adapt to it and keep going the next ride and the next ride without burning out as quickly.
In terms of the more physical adaptations your body makes, they are buried in the table @Captain_Doughnutman shows. You are training your body to burn fat for fuel (so you don’t bonk as quickly from lack of glycogen), you are teaching muscle fibers that can act as either fast or slow twitch fibers (called intermediate fast twitch fibers) to act like slow fibers (this takes a long time), etc.
In terms of how to measure how good your base is, that is somewhat subjective because its a season over season thing, but things like chronic stress load can give you a sense of how much continuous load you’ve given your body over the weeks. There is no finish line here, but it also limited by how much time you have before an A race.
You can also measure your progress quite well using a power curve. Here is me at the beginning of the season verse later on. You can see I am faster in every single time range from earlier in the season and can hold over 200 watts for an hour now verse 137 at the start of the season.
If you are new to cycling, you are better to invest more time in base than anything else. So that you don’t peak to early, when you get closer to an event you can do more race like specific training.
Yes, maybe your sprint won’t improve as much as if you specialized, but you’re entire power curve will improve with base training, your recovery will be better and your body (ligaments, tendons, muscles, cardo system) will be ready for the harder challenges with less likeliness of breaking down and you will be a much stronger rider.
One final thought, if you do nothing but base training, you’re not likely to win a sprint finish, but for a longer event you’re also not likely to get dropped completely either. When you are first starting out you want be able to handle surges from hills, etc. and recover. Base training does this very well.
Hope that helps!
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As you fatigue your carb stores deplete. You rely more on fat. Fat produces less energy per liter oxygen. For the same power output you have to deliver more oxygen to the muscles (heart rate, breathing, blood flow go up)
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If you’re not looking at cardiac drift - sorry, “uncoupling” - to determine when “base” is complete, what are you using it for? To see that you’re getting more fit? Doesn’t your power output already tell you that?
references?
Thought Friel was pretty clear about the same in this 2008 article:
While there is little on this in the scientific literature, the limited research available appears to indicate that when aerobic endurance improves there is reduced heart rate drift relative to constant outputs (power and speed). And, of course, the reverse of this is that when heart rate is held steady during extensive endurance training, output may be expected to drift downward.
Just a simple observation, and a simple tool. Use when appropriate. I’m glancing at it right now, because my fitness is down coming off a 3 months resistance training, lack of riding mostly due to smoky air, and there is no reason to subject myself to testing. At this point I can simply do long rides to zone2 HR, most recent 3 hour z2 ride had 20% decoupling LOL, and pay attention to how I feel while also taking quick post-ride glances at decoupling to gauge increasing fitness. At some point it will be obvious its time to throw down a mark and test, but until then decoupling is simply a practical tool to use along with other practical tools (like RPE, hrTSS, etc.). IMHO the perma fit crowd is reading way too much into decoupling, I think we agree on that.
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ah okay i see where our disconnect was. I think it still would be useful even though we have power, no? For sure you can see your power going up but not every ride is a max effort and this just gives you another measure to track.
But that is provided that it does in fact change with fitness. If all it shows is “you have been exercising” then that’s not super helpful.
Aerobic decoupling as discussed by Friel, et. al. is really only half of their discussion. Efficiency Factor - power (or pace for runners) at a given HR is the other half. Neither alone nor in combination is good enough to say, “your base is adequate” without also knowing what you’re training for. The base someone needs to finish a half-Ironman is quite a bit different than the base one needs to qualify for Kona, so the EF goal would be different, as would the decoupling goal ride or run length.
You can do “base” training forever and continue to improve your EF as long as it will go up and decoupling remain zero for longer and longer times with that type of training and keep getting faster and faster. That’s probably what everyone SHOULD do in the absence of goal events… but eventually performance suffers because you lack specificity toward goal events, so we move to Build and Peak/Specialty type training.
I don’t think many would dispute that if you are going faster or putting out more power for a longer duration at the same HR, your fitness/base have improved. Anyone claiming to have an absolute answer (or claiming that Friel said he did either) about “when is my base finished” is misguided. The question is, “When is it good enough to achieve my goals?” Now you can examine mostly objective pace, power, HR, and duration metrics to work with to answer that question pretty well.
Start here.
I believe that the central governor at work. Your brain stops you from doing one more rep by reducing the recruitment of muscle fibers in a given muscle group. It’s this decrease in muscle fiber recruitment that causes you to experience fatigue in your muscles. But it’s not your muscles that are tired. It’s your brain’s effort to protect your muscles and body from further damage. (Part cut and paste above).
I believe, as it shuts down muscle fibers due to above, your system needs to work harder to recruit new fibers.
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Friel is not listed as an author?
I’m wondering about the expression of “stop! you’re ruining your base” when in the midst of a traditional base, someone starts to go harder in a group ride.
Is it possible to “ruin” a base built with the sweet spot approach?
Basically every workout that leads to aerobic adaptations is you base. Z2, SS or threshold workout contrubute to your “base”. You cannot ruin your base other than with detraining. Your training composition my lead to different adaptations than purely Z2 but these still will be adaptations to your base.
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I agree with what you say but I would like to add something out of my own experience. I recently had to reduce the number of hours (from 15hrs to 9hrs) I ride my bike per week, and therefore I started doing more long SS intervals in less hours. My short power (and here by short I mean anything from 10 minutes to 2 hours) is better than ever.
However, this weekend I did a not too hard not too easy 3hrs 30 minute ride but I had not ridden more than 2 hours in a row for a month. While I felt really good during the ride the fact is after the ride in the afternoon/evening I was feeling much more tired than when I was doing 15hours per week and long rides regularly.
This is personally what I understand by “base”, the capacity to ride for hour after hour and day after day without tiring. Take any world tour cyclist and sure their FTPs are great but I am sure there are out there some amateurs that could match their race pace for a couple hours. However there is absoloutely no chance any could do 250 km or a Tour de France at that level.
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