Great info, much appreciated! Yes, because of my spotty on-again/off-again exercising history, I’m back at the point where just increasing my training is going to help. But I need to be more conscious about it this time and keep the intensity down so that I stick with it. That’s the plan, anyway, which is why I’m trying to get this HR vs ventilatory marker question a bit more settled in my head.
After writing the stuff below, I just found a paper that says that ventilatory thresholds match lactate thresholds. It’s here:
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0163389
“Lactate threshold tests can be a valid and reliable alternative to ventilatory thresholds to identify the workloads at the transition from aerobic to anaerobic metabolism.”
Funny how they put it in reverse of what a person training might want, because they are the researchers usually looking at lactate! But your experience agrees with what they report.
This may also be useful or interesting if you have not seen it:
https://link.springer.com/article/10.2165%2F00007256-200939060-00003
“Lactate Threshold Concepts: How Valid are They?”
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My MAF HR is 131 bpm (180 – age), but I use 135 as my TftNA Zone 1 top HR (from using an estimated max HR of 180). I’ve been only nose-breathing while biking (mostly bike trainer) and jogging the last couple of weeks, and my “labored but comfortable” nose-breathing is matching that HR pretty well.
My “labored but uncomfortable” nose-breathing (where I’m having to consciously keep my mouth shut) is about the top of my Zone 2 (144 bpm), so the TftNA Zones seem to be about right for me now. I’m going to watch both as I train this winter and hope the HR creeps up with the same breathing along with increased pace (please). I think it’s going to be a very slow process for me.
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I really don’t understand what reason is behind that 50 bpm difference you mention between biking and uphill hiking/running (why such specificity?). I looked at some of the literature on lactate thresholds, but it’s a big, confusing (to me) field! (The papers appear to be mostly about AnT, what seems to be called the “MLSS”, maximum lactate steady state, which can be maintained for 30-60 min). I know some of the physiology but certainly not to the detail required.
They do mention how it is commonly known that heart rate at threshold (I think it was both AnT and AeT) is lower in cycling than in running (presumably on cycle ergometers and treadmills). But it wasn’t 50 beats with such a difference in perceived exertion!
Maybe it’s about “poor” recruitment/poor efficiency (with poor being relative to that amazing hiking AeT you have)? But you said you have significant previous experience biking, and the brain remembers that stuff. With that hiking AeT, your ST fibers must be aerobically very efficient, meaning they can process a high lactate delivery from themselves and from any working FT fibers. So what recruitment pattern would cause a high lactate load at a lower exertional stress/lower physical load of pushing bike pedals vs. hiking?
Is that “poor economy”, where the brain recruits larger units to do a lower work load, and maybe it’s much higher FT recruitment during cycling? That sounds like the opposite of what is normally said, that one has to do a load causing high perceived exertion to maximally recruit and that novices are training that at the beginning, leading to quick strength gains that are due to neurological reasons and not muscle fiber development. Instead you are highly trained and have low perceived exertion on the bike.
Yes, the muscle mass use (higher for hiking—stabilization and bodyweight support) would explain the disconnection between heart rate and exertion. (i.e., your CV system is efficient and can provide a lot of O2 to working muscle, and you need less on the bike). So that should mean you do have less muscle working on the bike. But that would explain heart rate but not lactate levels. Why is it that with fewer working motor units/muscle fibers, those fewer fibers are generating much more lactate or generating lactate in such a way that it is not metabolized by your other fibers/ST fibers, which the hiking AeT shows are very highly trained and efficient at doing exactly that?
I don’t get it! Well, clearly I may not have the framework correct and am not looking at this correctly either.
Maybe it is max strength? And that on the bike max strength is limiting, which is not true on the hikes? But I imagine you are plenty strong and not the stereotyped weak-marathoner but more of an all-around strong mountain athlete.
Maybe it is just economy and that biking economy is much different than running economy, but that runs into problems as above.
Lactate is reported to be a major heart fuel during exercise, so maybe your heart, which is not working hard when biking relative to its capacity, is not removing much lactate, leaving more for the other tissues to process (and so get overloaded). I don’t know if that is a reasonable possible explanation or not, and still I would think your ST fibers could handle the load, as they seem to be very good at it based on your hiking AeT.
Lactate is also a pH buffer, protecting against (instead of causing) acidosis (because it takes protons to create lactate from pyruvate, which is what happens in the body). So maybe that’s one use here, and so you need the lactate during the less-trained activity (cycling)?
It’s an interesting problem. I do realize that the main point, however, is that you said your breathing follows your AeT and not your HR. Maybe I can ponder lactate use during my long slow runs (which turns into walking during uphills or I quickly move out past AeT). For me, they are slow!
Thank you for the info on your direct experience!
René
