Aerobic Deficiency 'Syndrome' For Mountaineers

​​In this episode, we talk about the concept of Aerobic Deficiency 'Syndrome' for mountaineers and why I believe the conversation around this topic needs to change. 

Episode Chapters:
0:08 
Introduction to Aerobic Deficiency Syndrome
4:15 
The Reality of the Syndrome
8:11 
Testing and Its Implications
10:45 
Training Methodologies Explored
14:37 
The Language We Use Matters
16:13 
Conclusion and Key Takeaways
​
Episode Transcript:

​[0:00] All right, hello, hello, ladies and gentlemen. So in today's episode,

[0:04] we are talking about aerobic deficiency syndrome for mountaineers. Now, from the get-go, I'm going to be really, really, really honest. I personally believe that the conversation and the presentation around the idea of aerobic deficiency syndrome in the mountaineering community, I think it's dumb. I think the topic itself is interesting. I think the way it's presented, the way it's communicated is really, really, really bad. And in 2026, I personally think it needs to change.

[0:36] So with that being said, let's get into it and I'll kind of explain what I mean here. Now, before I go any further, let's just give a bit of background. If you haven't heard of it before, aerobic deficiency syndrome is a term coined by Phil Maffetone. Phil Maffetone, massive name in endurance world. It's been promoted over the years in the mountaineering community by some of the bigger names when it comes down to training. And if you type in aerobic deficiency syndrome into Google, you will see them pop up. Now, the whole concept around this is very, very, very simple. Now, essentially, when it comes down to our energy systems and how we create energy during exercise and during movement, we have our aerobic energy system, we have our anaerobic energy systems. In the ideal world, our aerobic energy system will provide fuel and provide energy for our lower intensity exercise. And in an ideal world, our anaerobic energy systems will provide fuel when we're working a little bit harder at higher intensities or whatever it may be.

[1:36] Now, the whole idea around this particular syndrome in quotation marks is in our training, if we spend all our time or too much time training high intensity, training short, sharp bursts of exercise, training really, really quick pace or whatever it may be, the body will naturally be training those anaerobic energy systems more. And over time, the body will get used to what you use. So more and more and more, the body will get reliant on these anaerobic energy systems. If you're living day-to-day just doing general sports, not a big deal. For an endurance athlete specifically, this is detrimental to our performance because our aerobic energy systems are designed to help us go for long durations with minimal fatigue. Our anaerobic energy systems are designed to only go for short periods. So if we're relying on them for longer periods, that's going to lead to earlier fatigue and some other consequences. And the whole idea around this, again, syndrome in quotation marks, is if you reach a point where your aerobic energy system is so under-trained to an extent, you are then deemed deficient in quotation marks.

[2:47] So how do you know if you're deficient? Well, there's a few different measures. Like some people sort of say like, okay, if you are just the type of person who you go up a little bit inclined and all of a sudden you're out of breath. Or after an hour of exercise, you feel like you need to eat. Or if you can't carry conversation during exercise. Or if you're just absolutely knackered after a certain period of training or whatever. And those are measures that are really, really, really common. Or it's often promoted that like, look, if you dive into some certain fitness assessments, you can be specifically defined as having aerobic deficiency syndrome is if you do some assessments and you realize there's a greater than 10% difference between your aerobic threshold and your own aerobic threshold. What are those? How do you test it? I'm not going to go into this. You can look it up online, whatever it may be, but it is very, very common in the mountaineering world to test these things. Now in concept at a top level sure this all makes sense and it does sound relevant for mountaineers and absolutely 100 i agree that as a mountaineer in training you need to be aware about the intensity of your training you need to be aware of the energy systems and how you're developing it as a trainer and as a whole general concept putting more focus into your aerobic energy system absolutely makes sense.

[4:07] But in practice, as much as in theory, that whole thing's great.

[4:10] In practice, there are some real issues with this topic and the way that it's presented. Now, first and foremost, and I think this is just a major issue, and it's 2026, I cannot believe we're still talking about this. Aerobic deficiency syndrome is not a real syndrome. It's not a medical diagnosis. It's not something you go to the doctor and they say, you have this syndrome, and in no way should it ever be equated like a medical thing.

[4:40] Using the term syndrome, or diagnosing someone with this syndrome in quotation marks, or curing someone from this syndrome in quotation marks, that type of language is honestly ridiculous. Now, you may think, okay, well, cool, like, why does that matter? Well, as a trainer, it may not matter so much to you. But as a coach who is working with multiple people around the world in different situations, coaches need to be aware that words matter.

[5:10] And what may sound innocent coming out of our mouth as a coach or written on paper can have genuine repercussions and consequences for so many people. This may sound a little bit wild and be like, well, come on, Rowan, no one's really thinking it's a real syndrome or whatever it may be, but it does happen.

[5:29] And one thing coaches need to be aware of is that anything sounding, even the tiniest bit medical sounding, people can absolutely hyperfixate and obsess on. And they can genuinely believe that if they've been, in quotation marks, diagnosed with quotation marks this syndrome, that there's something genuinely wrong with them, that their body is wrong, that they are broken because they have this issue and no matter what they do, they can't fix it or cure it or it doesn't change. Now, this may sound hyperbolic to some people and it definitely doesn't happen to everyone, but there are many, many, many people who fall into this category. And I can tell you from personal experience, the amount of conversations I've had with people who have fallen into issues like this. I've had conversations around aerobic deficiency syndrome and a bunch of other things that are very, very similar in the world of training and fitness. And the amount of conversations I've had with people who have obsessed about these things for years, who've genuinely felt like things were wrong with them and problems with them or whatever may be, it would scare you the amount of times I've seen this. Or if you just want to get a snapshot for yourself, you can literally go into any type of online forum related to mountaineering or just endurance sports, trail running, cycling, whatever it may be, and you'll see people bring this up. On this subject, you'll see so many people sort of using the words, I've been diagnosed with ADS, like aerobic deficiency syndrome. I'm trying to cure up my ADS. Um, um.

[6:58] You see people putting up questions online saying, hey, I'm doing this with my training and I'm worried about this. And then other people will reply saying, you have aerobic deficiency syndrome, diagnosing them online. And then these people who are just asking for help with something, all of a sudden they think they have something wrong with them. They have this syndrome, which they know nothing else about, but someone's told them that they're wrong. We see people getting so worried and hyper fixated on this one thing that I've seen people online saying they're delaying starting a training plan until they fix this thing, or they're delaying doing endurance work or strength work until this type of thing is cured or resolved. I've seen multiple people saying they've been trying to fix this issue for six months or 12 months, and they're just still worried they have this syndrome. This stuff is plastered in any community which relates to endurance sports. And we know that whenever one person is talking about this publicly online, there are always so many other people out there who are thinking the same thing. And realistically, in 2026, using this term, aerobic deficiency syndrome, it just needs to stop. It's crazy that it's still used as a term.

[8:12] So that's my issue number one. But beyond that, let's say we took out the word syndrome and we just used aerobic deficiency. And we said, look, this is something that some people run and run with. In all honesty, again, I understand it. It makes sense. Top level, it all is perfect. But honestly, I think the whole idea around testing for this and obsessing about this and having conversations about this and really, really just like keeping this top of mind, I think it's a bit silly.

[8:43] Realistically because like whether or not you have aerobic deficiency in the context of training for mountaineering it's not really going to change what good training practices are going to be for your particular sport because realistically when you look at it every single mountaineer, should be in their training prioritizing aerobic capacity work. The bulk of our training hours as a mountaineer should be focused on that. Yes, we want to do other things, but the bulk of our training should be there. And whether you are incredibly aerobically trained or whether you're incredibly aerobically deficient, the bulk of your training hours is always going to be doing this.

[9:31] On top of that, every single mountaineer out there will benefit from being intentional around controlling your intensity, especially for these sessions, making sure your low intensity is actually low. So someone who is incredibly aerobically fit, they may know how to do this already. Someone who is aerobically deficient may just have to go way slower. And again, it's not like the conversation would change if you had someone who was brand new to training or relatively new. Whether they were incredibly aerobically deficient or they were actually naturally pretty good, we would still want them to control their intensity. We would still encourage them to fit into these things. The conversations would still be the same saying, we want to develop your aerobic energy system, whether you're deficient or whether we just want to improve it. It's the same.

[10:18] On top of that, it's every mountaineer out there will get benefits from doing small amounts of targeted moderate and higher intensity work. Whether you are incredibly aerobic trained or incredibly aerobic deficient, it's still going to be beneficial. And every mountaineer will get benefits if you're just shifting away from that generic HIIT or CrossFit training and actually tailing the training towards your sport. Now, I fully, fully, fully understand.

[10:46] Some people might be thinking, oh, okay, Rowan, you just rushed over a point there. Like.

[10:52] What do you mean every mountaineer will get benefits from doing moderate and higher intensity? Because I understand some people do recommend avoiding any type of moderate or higher intensity training until you have a very specific aerobic base. And some people say until you can be trained out of this particular condition, you should either avoid entirely or very, very, very minimize this higher intensity training. And sure, that's fine. And a lot of people do this. A lot of people see success for it. But as I've talked about on this podcast before, this isn't the only way of training. You don't have to do this. It is perfectly fine. It is perfectly possible. It is perfectly legitimate to still do some higher intensity training in your week, even if your aerobic fitness is lacking, even if you are termed deficient. As long as the majority of your training volume is at that lower intensity, as long as your emphasis is still developing that. And as long as you are confidently and correctly controlling your intensity for those sessions, it's not going to be an issue.

[11:56] And I've seen people sort of say, even to the extent of even doing any amount of high intensity work, if you're aerobically deficient, it is going to be a detriment to developing aerobic capacity. It is going to slow your improvement. It is going to get in the way of things. But in all honesty, It really just comes down to training hours. As long as you're allocating your training hours properly, you're fine. The argument there is if you have 10 hours in the week and you're dedicating nine hours to aerobic capacity work and maybe do an hour of high intensity, well, yeah, if you could do 10 hours of aerobic capacity, it probably would improve that a bit quicker, but come on.

[12:34] There's room to fit multiple qualities of fitness into a training. And then you may go a bit further. And I know the next argument some people would make is they're like, well, there is some type of interference effect here. Different levels of intensity will trigger different molecular signals in the body. Different things which will conflict with each other and get in the way and whatever may be. But in all honesty, if you're worried about that, I think that really more comes down to how you structure your programming week and how you separate the sessions and introduce your intensity and this and that more than anything. You don't have to be scared of high intensity work as long as you are nailing your lower intensity stuff, which comes back to the very first thing. It's like, yeah, people with this issue have got it skewed, but everyone should be having that conversation anyway, regardless of this deficiency or not. And yeah, again, you could argue that you'll probably see better benefits from certain types of higher intensity training if you have a better aerobic base, but that still doesn't mean it's not going to be beneficial or useful to incorporate at different stages. It's just a funny conversation, I personally believe.

[13:38] And realistically, coming back to it, I understand the people who have this type of deficiency, trying to convince them to change their training methodology around and trying to convince them to leverage that lower intensity, which, you know, a lot of people don't want to do and it doesn't feel like work and it's a whole thing. I understand that using this testing can be a powerful way to identify this for certain people. So we can put a number behind it and say, you know what, look at all of this and you're deficient. We use these words and encourage them and all of that. I understand as a use for change, that can be useful.

[14:13] But we need to be aware that that is useful in certain contexts, but we need to be aware of these conversations because again, you can go online and you see people who have just been trying to fix in quotation marks, this thing for years on end. They just get obsessed about it. They get hyper-focused. They get mentally down when something's wrong with them. When realistically, it's just a case of they need to improve their aerobic fitness. They need to tailor their program and their training a little bit better.

[14:38] This kind of comes into the same category. And like I mentioned before, I've had so many conversations with this type of thing of people over the years. You know, the same category, I'm sure you've heard the term of gluteal amnesia, or like, you know, your glutes being asleep. And years ago, there was this guy who did these studies on lower back stuff, and he coined this term gluteal amnesia, saying, look, your glutes don't work, and this and that. And for years and years and years and years, people went to physios or physical therapists or trainers, and they got diagnosed with this gluteal amnesia. But it was just a made-up term. Basically, it just means your glutes need to get stronger, which is fine. But even now, 15, 20 years after this coin was termed, I have conversations pretty much every couple of weeks where people say, oh, I have glute amnesia and my glutes don't work. And they've been obsessing about this for 10 years. Or another thing is like lower cross syndrome, which is the whole concept of like, look, if your hip flexors are tight, that'll lead to weak glutes and this and that, and it ends up like pulling things out of alignment and all of that. And again, it's kind of like.

[15:41] Yeah, there is some merit to that, but the whole conversation of calling it a syndrome just messes people up.

[15:50] Words matter in the coaching scheme. And I think calling this a syndrome right now in 2026 is a bit of an issue. And even that, the whole conversation, just say that people who need more aerobic fitness just do more aerobic training. And all mountaineers need more aerobic fitness, whether you are untrained or

[16:08] super trained, I don't know. I think it's just one of these things which is just overcomplicated. I think it's unnecessary. So there we go. That's my little bit of a rant. Realistically, when it comes down to this, if you do come across this term online, the main things I want you to get out of this episode today. Number one, this is not a real syndrome. It should in no way ever be considered to have medical consequences, to be anything anywhere near a medical issue or whatever it may be. All it means is your aerobic energy system can do with a bit more work. If you are starting a training plan for mountaineering or restarting a training plan, just know you don't have to test for this. It's not a big deal. As long as you have some measure of managing your intensity and making sure you are fitting in your aerobic training, testing for this, it doesn't really matter whether you're deficient or not. You're still going to do pretty much the same training. If you do want to test for this and you do identify that you're deficient in yourself, there's nothing wrong with you. It just means you need to focus on that in your training. You need to manage your intensity, focus on your lower intensity stuff. And if you've been doing a lot of higher intensity stuff, you need to change your emphasis.

[17:14] And realistically, I know people say this, but I'll argue there are no set points where you can and cannot do higher intensity training. As long as you are always allocating the majority of your training hours to aerobic capacity, as long as you are not neglecting that, not turning everything into moderate or high intensity, you can do high intensity training at any stage. The application of that will be very different from person to person, depending on what they need, where they are with their training, what their energy can handle, and all of that. But intensity isn't a bad thing. It's just overused. Small doses, perfectly fine. So in all honesty, that's enough for me. The whole term, whenever I see it, it does drive me up the wall a little bit because it's 2026 and I cannot believe it's still being like talked about in this way. Hopefully today it's just brought maybe a little bit of just common sense to this conversation, maybe a little bit extra context for people who do have a habit of hyper-fixating on these type of things. And if you haven't seen this type of thing before, hopefully this will give you information. If you do run into it, you won't go down that rabbit hole. So with that being said, I'm going to wrap things up here. I hope that makes sense. I hope it helps a few people. Hope that was interesting, and we'll talk to you soon. Bye.

Want to get
fit, strong and resilient
for your mountaineering adventures?

Check out
​The Online Summit Program