Aerobic base training vs. supplemental swim training | Uphill Athlete

Aerobic base training vs. supplemental swim training

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  • #7144

    Does UA have any general guidelines for supplemental training in addition to the exercise found in the 24-week mountaineering program? I’m in week four of my program and had VO2 and metabolic fuel tests performed; my AeT is at 107. I also recently completed a half ironman, and would like to continue swimming to at least maintain my current capabilities, but even at my slowest swim pace I’m above AeT.

    Overtraining concerns aside, will this additional exercise above AeT hinder my aerobic endurance adaptation? I think that you had advised against HIIT in a separate forum post, but I’m not sure how much this would relate to swim training.

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    Anonymous on #7150

    Hi Benjamin,

    Do you have some more information about your test? More specifically, do you know at what heart rate your anaerobic threshold is? How big a gap is between AeT and AnT?

    If you divide your AeT HR by your AnT HR, and then multiply the result by 100, you’ll see what percentage of AnT is represented by AeT. If AeT is less than 90% of AnT, then you should continue to work on building up your aerobic capacity by keeping all activity below AeT (even if it’s very slow.) This applies to all activities, no matter how slow.

    For example, I don’t bike very much. But when I do, my AeT on the bike is far lower than when I’m running or skiing. Even though the HR of AeT is much lower while biking, I still stick to that relatively low HR, because I want to keep things aerobic.

    This can be frustrating, I know. But slowly, over enough weeks and months, you’ll find that your AeT will gradually rise. As a rough rule of thumb, once AeT is 90% or greater of AnT, then it’s time to start adding some intensity, but not before.

    If you add intensity before that point, then (to quote Scott J) “you’re putting icing on a cake that isn’t fully baked”.

    I hope that helps clarify things.

    Scott (S)

    Anonymous on #7175


    As you may have read in our book and on this website; specificity of training trumps non-specific training every time. There will be almost no transfer of training training effect from swimming to foot borne mountain sports unless your fitness is at a very low level, when any aerobic activity will help. It is IMPOSSIBLE to optimize training for two different training goals in the same training period. This is why elite athletes specialize and we are awed when an athlete competes in the summer and winter Olympics in two different sports. It is so rare!

    Even though I doubt the high intensity swimming training itself will have a major negative effect on your running aerobic base (here’s the specificity issue again) it will not doubt reduce the time and energy you have available to train for other training.

    Assuming your test was on a treadmill running and so you really do not have an idea of what your swim AeT is. You could test this in a pool by doing blood lactate testing and that would help inform your swim training just like it does your run training. With an AeT of 107, unless you are 70 years old, you would benefit greatly from a prolonged aerobic base building period to elevate both the AeT HR and pace.


    benjamin.connel on #7199


    This is helpful, thank you. My AnT is 156 bpm, which puts me at a ratio of ~67%. I’m assuming that I have a relatively well-developed anaerobic capacity from my powerlifting/HIIT background. Since I’ve recalibrated my aerobic runs, my pace to keep a HR of 107 bpm is somewhere around 13:30 min/mile… painfully slow but something I can work with nonetheless!

    I recognize the potential for overtraining though by incorporating swimming into my weekly routine. The aerobic workouts would definitely take precedence if I’m feeling overly fatigued.



    lionfish90 on #7208

    Scott Semple: You said, “[M]y AeT on the bike is far lower than when I’m running or skiing.”

    How did you determine that? Is your breathing at that point “labored but comfortable nose-breathing”, labored uncomfortable nose-breathing (which for me means have to much more consciously keep from mouth-breathing), or unrelated to breathing and more about heart rate or perceived exertion based on a lactate or other lab test?

    Ben: What is your breathing like at your AeT of HR 107? Good luck with the slow runs; I’m there myself!

    Thank you,

    Anonymous on #7218

    Hi Rene,

    I have a lactate meter. I do my own tests for a bunch of different things, including spot tests during workouts.

    When I was biking a lot several years ago, my bike AeT and weight-bearing AeT were similar. But now that I rarely ride my bike and do so only for recovery, my general bike fitness has declined substantially.

    To find my bike AeT, I did some spot tests this summer, zeroing in on 2 mM. I found that my AeT on the bike was almost 50 bpm lower than my weight-bearing AeT.

    Having my own meter has provided a great education. Near the top of the list has been the lesson that aerobic training is super-specific.

    After a couple decades in the mountains, I’m metabolically much more efficient at striding uphill than at any other activity. I have decent uphill fitness, but I’m a powerless biker and a very slow runner in the flats.


    lionfish90 on #7239

    Scott Semple: Awesome, thank you! You are in a great place to answer a burning question–

    **In your experience, is nose-breathing a reliable AeT monitor for multiple training activities based on your lactate testing?

    **In other words, Would you say your breathing more closely follows what your lactate level or what your heart rate is saying about current (or average) intensity of effort when running and biking? (given that the HRs are so different at AeT)

    I don’t mean for my blah-blah-blahing below to mask that main question 🙂 .
    I’m a flatlander who does a couple of 1-week mountain trips per year (only talking Class 2/3 up to easy 5th, mostly in the Sierra). I try to replace much running with biking b/c of sore knees, niggling pains from impact, nursing a torn meniscus that flares if I run too much. Not surprisingly to me looking at my training logs, my fitness has not been good enough for even these relatively straightfoward objectives; it’s obvious to me my training has been much too haphazard and flaky. So I am (re)committing to Transition/Base consistency for next summer’s trips.

    One truth is that some people (such as myself) are far enough on the unfit side of the spectrum that the reality is I do not necessarily need to sweat the details but just need to sweat–put in the effort and be consistent. THEN I can worry about these things. The basic message of TftNA I need to take is 1) stay at/below AeT for long hours, 2) include strength training at all stages (general, max, ME), and 3) be consistent. Together, these mean have a plan but don’t be beholden to it and remember–to be consistent (train again tomorrow), I can’t train too hard today (Death by Threshold).

    What you say (50 bpm lower!) is some serious specificity! The human condition, sometimes a bummer. Or, more optimistically, I suppose one could be happy about how malleable our physiology is, how adaptable to a wide range of demands (given the time, commitment, and effort to train for them), and how trainable different specificities are (just not really at the same time!).

    Thank you for your insights on gauging intensity to remain at/below AeT in multiple modes (biking, running, and rowing, in particular).

    Anonymous on #7257

    Hi Rene,

    Here’s a long answer…


    Good question. The answer: Yes. Given a proper warm up*, I find nose breathing almost always correlates to ~AeT.

    Another thing that I’ve learned is that central adaptations (of the heart and lungs) aren’t necessarily coincident with peripheral adaptations (of the locomotive muscle). This is my anecdotal explanation about the difference between my current weight-bearing AeT versus bike AeT.

    For example, my weight-bearing AeT has been in the low-180s for the last several years, while my last spot test on the bike at ~2 mM (~AeT) was in the low-130s. However, although the lactate samples are similar, the levels of exertion are very different. On foot, I have to limit the amount of training I do at AeT, because it’s quite stressful. On the bike however, in the 130s, I can stay there quite pleasantly for hours.

    My weight-bearing AeT intensity is much closer to my anaerobic threshold, while my AeT on the bike is far from it. The training stress seems to directly correspond with the percentage of AnT that is being used. Conveniently, this makes something like Training Peaks (which measures training stress relative to AnT) quite useful, but not in the way that it’s advertised.**

    Also, the amount of muscle mass being used for weight-bearing sports would put a greater demand on the heart and lungs, so that is also probably a factor in the difference in heart rates. (Although peak heart rates seem to be the same.)


    I hear ya about the flat lands; I grew up in Saskatchewan. I also hate flat runs lasting longer than an hour, so I can empathize with the challenge. Flat runs really tighten up my hips as well.

    If you don’t have a long training history, then you’ll benefit from any type of training. And if you have injuries, then whatever you can manage is what you should do.

    I think that Scott J. would agree: The theory and recommendations are just theories and recommendations. They all have to be adapted to the individual, whether that’s the method, the volume, or the intensity. Don’t use that as an excuse to avoid specific training, but staying healthy and motivated is the top priority. Do what you can, and do it as consistently as you can.

    I hope that helps.


    * For me, a proper warm up is nice and easy for ~20′ followed by a gradual 10′ ramp up to AeT. I don’t like to exceed AeT during a warm up, but that could be because most of my events are ~2+ hours, so AnT is not really required.

    ** Training Peaks markets their metrics as creating and measuring fitness, but for me, that’s not the reality. The metrics are, however, very good at tracking fatigue.

    Anonymous on #7266

    I had another thought on this: as I mentioned, nose breathing seems to consistently correspond to AeT given a proper warm up.

    That being the case, if you have to choose, I would recommend going by ventilation rather than a metric, whether that be heart rate, power, or pace. Ventilation is a real-time reflection of our current fitness in the current activity while a metric is a past-time reflection of where we were last week, last month or last year.

    Fitness tests that identify thresholds per metric are snapshots for the day that the test was done. With chronic training, those metrics will continue to be relevant, but after a long lay off or with a change in sport, they’re much less reliable.

    Ventilation, on the other hand, is always a here-and-now reflection of where we’re at. This is especially helpful in races. In the past, I was a slave to my heart rate during races, but it’s been much more effective to learn what my breathing feels like at various intensities, and then target those ventilation rates for a desired intensity.

    lionfish90 on #7268

    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:
    “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:
    “Lactate Threshold Concepts: How Valid are They?”

    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.

    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!

    Anonymous on #7269

    Sorry for the confusion. I think it’s fair to say that I’m an untrained cyclist.

    I only biked seriously for the summer of 2014. Before 2014, almost no biking since I was a kid, and after 2014, only for recovery. In contrast, I’ve been putting in hundreds of hours per year climbing and skiing in the mountains for 18 years.

    I could be wrong, but my guess is that the huge difference in time-spent is the reason that I have such different levels of efficiency in each activity.

    lionfish90 on #7278

    Yes, I got a little carried away ? . I’m amazed, like many before me, by the specificity of training. Even now, many of the factors responsible for why general training or cross-training does not transfer to specific sports are still unknown. Like here:
    “…Using sprinting performance as an example, exercises involving bilateral contractions of the leg muscles resulting in vertical movement, such as squats and jump squats, have minimal transfer to performance. However, plyometric training, including unilateral exercises and horizontal movement of the whole body, elicits significant increases in sprint acceleration performance, thus highlighting the importance of movement pattern and contraction velocity specificity….”

    I mean, what the hell, that’s been known for probably over 2000 years, even in an organized way, such as in ancient armies. I guess I am mostly surprised at how this lack of transfer appears to be true metabolically as well, as your example shows. But how else could it be? Clearly, some aspect of biking is taxing your system in a quite specific way which all of your prior training has not done much to optimize. On the other hand, you can tool along for hours because of that other training, while I would keel over way before. (And presumably, you could sharpen that with a sport-specific training period that would be possible only because of the previous work you have already put in to be prepared for hard, sport-specific training.)

    How little do we actually know about physiology that we do not have a straightforward explanation of the pathways involved to explain that, other than saying, “Ah, it’s the neural aspects and highly specific contraction velocity control”? I’m in science, so I feel I have some understanding of how difficult it is (and then some) to figure out exactly how something works in a biological system with all its complex and multi-layered interactions, but sheesh.

    Anyway, I can’t lose sight of the perhaps the main message of TftNA for me, which is that I have had way too much inconsistency (which I knew, just not the magnitude), too many rest days, too much giving up and time off, and some of that is from exercising too much in that “no man’s land” area: going too hard to recover well to go again tomorrow, too hard to efficiently train aerobic capacity, and not hard enough to at least efficiently train the anaerobic side of things.

    So thank you for confirming the recommendations here and in the book on using ventilatory markers as a good way to monitor intensity!

    Best wishes, and Happy Holidays!

    lionfish90 on #7279

    Oh, and to get back to the original poster on how his other training would relate to his swim training, I also ran into this, which may be interest (or frustration):
    Modelling the transfers of training effects on performance in elite triathletes.
    “…Swimming appears to be a highly specific activity, which does not gain nor provide benefits from/to other activities (i. e. cycling and running). The present study shows that cross-transfer training effects occur between cycling training and running performance in elite triathletes. A similar cross-training effect does not seem to occur for swimming performance.”

    Anonymous on #7297

    Hi Rene,

    One more thought: I love getting into the details and technicalities of training as well, but I sometimes do it too much when what I really need is to get out the door. Until I added consistency, gradualness, and modulation into my program, it didn’t really go anywhere.

    I’d say regardless of what they theory says, if you put those things into place first, you’ll see progress. You can fine tune things as required later on.


    benjamin.connel on #7352

    Sorry for the delay in response. Breathing at 105 BPM is actually fine; it’s the extremely slow 16-18 min/mile pace that’s driving me insane.

    I got testing done at a place local in Seattle called PotentRx. There’s another post that makes me question my results (Vo2 Max/AeT-AnT…..). I might get re-tested at the place that Scott Johnson recommended to verify.

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