Suggestion: Renaming ADS to FODS

  • Creator
  • #51282

    Hi guys,

    I think Aerobic Deficiency Syndrome is a misleading term and not pointing to the underlying problem.

    The underlying problem is in fact that fat oxidation is underdeveloped, and so the body is then relying on carbs instead of fat. Both forms of energy production are aerobic though.

    This is why I suggest to call it



    Happy to discuss!


  • Participant
    Emil on #51326

    I know that Maffetone admitted somethibng in that light of thought in a recent interview, that the aerobic/anaerobic dichotomy is oversimplification but convenient in explaining the whole model. All models are wrong… FODS sounds to me, though it does not need be, like a diet first approach and I think that will be rejected by a lot of athletes who adhere to a more traditional carb based nutrition.

    Dada on #51328

    I’m happy that you want to discuss this ?

    I see the point of convenience, but on the other hand the wrong dichotomy (aerobic/anaerobic) leads to the issue that people discard the theory bc “when even the name is wrong, how can the model be a good fit?” I’ve seen a couple posts like this lately…

    Hm, fat oxidation is a technical term of using fat as energy source. But I admit that some people might just read the word “fat”.

    What would you propose?

    Cheers Dada ?

    Thomas Summer, MD on #51345

    Can you eat a ketogenic diet (and be in ketosis) and have FODS? Or can you have ADS?
    Anyway, what about BDS… Base Deficiency Syndrome?;-)

    All models are wrong;-) it’s probably better to understand what it’s about!?


    Emil on #51355

    We need to up vote Base Deficiency Syndrome 🙂

    Seriously though, I find that the overemphasis on aerobic/unaerobic metabolic model undercuts the muscular-skeletal one, which is just as important in the base building for bipedal sports.

    Dada on #51390

    Thx Thomas for chiming in 🙂 (haven’t forgotten your Augustiners and Tegernseers…).

    I wounder if you could get “ADS” when you be on a ketogenic diet and then start to train. My knowledge in nutrition is quite shaky, but could you handle a lot of +Z3 training when you are on a ketogenic diet?

    I like the term BDS. For me it’s just not distinctive enough. For example, elite athletes with ADS have a huge base. No one denies that. But focus too much on carb oxidation and too little fat oxidation.

    The idea of renaming ADs came pretty much by this post:

    I mean he is right regarding the term.


    Thomas Summer, MD on #51400

    Deficiency should be understood as weakness, not as a shortage of the aerobic pathway. Your aerobic system always contributes the most to the energy expenditure, but so does the motor of a tractor compared to a Ferrari. And would you like your anaerobic system to contribute sooner or later? If that wouldn’t matter then we could hold our highest intensity forever. All the acidosis and metabolic byproducts, out of the anaerobic pathway, wouldn’t contribute anything to fatigue.
    I think we shouldn’t focus so much on the words, but more on understanding what it is about. It’s not a disease (so it’s unlikely that you find something on pubmed), but it’s a risk factor for poor athletic performance and development in long endurance sports.
    I would like Jason Koop to join the discussion. He is so much smarter than we are, so I think we could learn something;-))
    Bottom line: any term is made up. Why should we fear high intensity work?

    Jared Casper on #51429

    I’ve never heard of Jason Koop but based on that post I’m not inclined to give him much interest. He attacks the concept of ADS based solely on the name. His main arguments are that there aren’t PubMed using that name, and that we are primarily using our aerobic system doing anything over a few minutes so “obviously” Aerobic Deficiency Syndrome doesn’t exist. He says nothing about the actual content. He doesn’t argue and mention anything about spending most of your time below AeT. It’s not clear from his post if he thinks people should train above AeT more? But that is certainly what some of his followers got from that post (see comments) which I think is harmfully misleading. He seems to indicate that Phil, Scott, and Steve are advocating for no high-intensity training at all, which is just not true.

    Maybe the original idea that the name is perhaps a bit of a misnomer has some merit, although I agree with Thomas that if one of the main aerobic energy pathways (i.e. fat burning) is undertrained then the whole aerobic system is indeed “deficient”. But that post attacks the theory simply because of the name which is not doing any good for the community.

    I understand that the way the books/articles present the whole aerobic vs anaerobic dichotomy might be a bit simplistic or slightly wrong; my understand is that it usually all aerobic and the fuel of fat vs glucose is what is what we are really interested in. That said, it seems this is an area of active research with constantly changing and not-agreed-upon terminology, so a simpler model (and that’s all these all are is just models) that someone without a biochem degree can understand and that gets the point across seems preferred over a more accurate model that gets people bogged down in the details.

    russes011 on #51982

    AeT, according to UA, is the crossover point when one is using equal parts fat and carbs during exercise. I presume they like this metric because they believe that for prolonged outdoor exercise it is possibly more efficient, or simply more practical, to be able to exercise while remaining to the left of this point (more fat usage). Therefore shifting this point to the right by lots of easy training mileage is the goal.

    The amount of fat vs carbs one uses at during exercise, in general, is also determined by one’s diet. The crossover point mentioned above could be ‘confounded’, or shifted right or left independent of training status or fitness. For example, if I’m on a carb rich diet my respiratory quotient (the metric used to determine fat vs carbs) will shift towards a more carb centric result (ie shift the crossover point to the left—a more deficient AeT), independent of exercise.

    So how about anaerobic vs aerobic? This system, unfortunately, doesn’t overlap as reliably or conveniently with the above crossover point. In general, the point where lactate starts to appear in the blood is often thought to correlate (roughly) with this crossover point. There are probably too many variables to generalize here, including diet and training status, as well as the chronicity and type of each. Note this is not the point where aerobic vs anaerobic is 50/50 (equal parts of energy production). To simplify, this lactate crossover (or appearance) point may be better thought of as the point where the aerobic system loses control of the anaerobic system.

    Even when there is no lactate in the blood the anaerobic system is still in play to a significant degree. In fact, during all exercise both of these systems are always in play, and even more so for exercises that are not steady state, like trail running where the terrain is variable. During all exercise the byproducts of anaerobic metabolism, which are themselves fuels, that are built up in the cells, especially during minor to major bouts of more intense efforts, are “cleared” by the aerobic system. If the byproducts of anaerobic metabolism are too great, however, they spill into the blood in the form of lactate. Exercise can improve ones ability to clear these byproducts while they are still in the cell and prevent them from entering the blood stream; exercise can also improve one’s ability to clear these by products once they are in the blood. Therefore, simply playing housekeeper to the anaerobic system is another reason why exercise can shift the AeT to the right, at least when tested with blood lactate or ventilatory effort.

    Finally, aerobic metabolism can be fueled by either carbs or fats and which one does this best remains uncertain. The answer is probably: it depends. Nevertheless, stored fat tends to be the most practical/efficient source for prolonged efforts, depending on exercise intensity and dietary plan during these efforts.

    So what’s my point with all this fuzzy half-truth spray? I guess it is that the proof is in the details and semantics matter when arguing about these topics, and it’s important to be on the same page.

    FODS may not be the optimal name for the phenomenon we’re referring to since a shift in the AeT to the right (ie an increase in the AeT HR or an AeT HR within 10% of AnT HR) is not a fat dependent process PER SE, at least when lactate, ventilatory parameters, and likely HR drift are used to measure one’s AeT. In other words, folks who often fuel long outdoor endeavors with constant carbs like during ironman triathlons and the tour de France are not “aerobically deficient”. I believe it probably doesn’t matter if your diet is carb based or fat based when it comes to AeT and aerobic base, as long as you have become well acclimated in training to what your diet will be like during your event.

    On a different note, I think the verdict is still out on whether work below AeT, or work above AeT, or a combination of both, is the most efficient way to improve one’s ‘aerobic base’, even when things like AeT drift, 10% separation, respiratory quotient, lactate levels, and/or ventilatory rates are used as surrogates to confirm it. A balanced approach, that gets more intense and specific with time may be best. Having to achieve a certain threshold from an aerobic viewpoint before it being optimal to start polarized training seems a bit too restrictive (not sure). These points speak to the utility of calling it base deficiency syndrome: I’m not a fan because what base are you referring to? Aerobic base, anaerobic base, or perhaps both, since they can’t truly be separated—eg how can you truly developed one’s aerobic base without stressing it with enough anaerobic byproducts to make it more efficient at clearing them, which is one of the fundamental components of having a good aerobic base? (Note: I’m leaving out the fact that there is yet another enzymatic pathway [AMPK] that can develop one’s aerobic base—one that is stimulated by HIIT, and not long slow distance per se, and unrelated to the housekeeping).

    In summary, I’m not a fan of the words deficiency or syndrome, but UA’s use of the term ADS is perhaps the best compromise considering the points I try to make above.

    Sorry this as so long winded and didactic (and perhaps wrong in spots). I also want to post later about why I think Koop is both wrong and right.

    russes011 on #51989

    Dear Dada,

    I read the instagram link you provided as well as the author’s responses to the comments. I also listened to one of his podcasts. He appears to have a bruised ego because Steve didn’t have the time to do a discussion piece with him for a magazine article–so he’s attacking UA’s concept of ADS on Instagram. I don’t think a debate with this person is warranted or advised. Nevertheless, Steve or Scott having a debate with another open-minded, thoughtful, and professional person regarding the physiology and semantics of ADS would be great.

    1. The lack of peer-reviewed articles on the topic neither proves nor disproves it’s validity. ADS does possess inherent logic, however, and I presume empiric evidence based on UA’s coaching experience.

    2. Just because all movement has an aerobic component, does not mean everyone’s aerobic systems are equally developed. Compared to a seasoned ultrarunner I’m aerobically deficient, but compared to a coach potato sprinting out the door I am not. It all depends on the point of reference.

    There’s an old adage in running: “have a problem?: just run more” (as in: are you overtrained, injured, plateaued?: just run more). Countless high school cross country coaches over the decades have probably mumbled these words to complaining students: just run more. What does this mean? It means that if you have a problem with your training the answer often comes back to you having an insufficient, or inconsistent, base: ie ADS. That is, the solution to most issues is just to drop the intensity and build more mileage: simply run more. Running more, or building more of a weekly base, is often part of, or all of, the solution, regardless if you’re hurt, plateaued, or overtrained. I feel that many, if not most, coaches and athletes have experienced this phenomenon in their own careers. All that UA is trying to do (I presume) is codify this old adage so that it may be more readily communicated and measured, hence the term ADS. I commend them on their efforts–it will be, and has been, an uphill battle for them to convince many, but hey, you know something: they’re good at going uphill.


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