Simulated Altitude Tents For Mountaineers

In this article and podcast we are talking all about simulated altitude tents for mountaineers.

​And I am answering the question of whether I recommend altitude or hypoxic tents for mountaineers going on a high-altitude expedition.

This is a really common situation:

A mountaineer books on a big, high-altitude expedition. The problem is, they live at sea level with no convenient access to altitude before their climb.

Maybe they live in Australia with absolutely zero mountains. Maybe they live in Texas and can get a weekend or two at a bit of altitude after some travel, but not much more and their preparations.

Whatever the situation, they are nervous about the high altitude (which is fair enough!).

They are investing so much time, money, and effort into this dream climb. And they are worried about altitude sickness, about acclimating properly and having the thin air holding them back.

So they are looking for any edge they can get.

One of the first things mountaineers will come across in this situation is the idea of simulated altitude training.

Using masks, chambers or tents to simulate the effects of altitude, and (potentially) prepare them for their climb.

I will often get the questions from mountaineers I am working with (or chatting with):

• Should I be using an altitude tent?
• Will altitude tents help me prepare for the high altitude?
• Is there anything else I can be doing to prepare for altitude?
  
  

So today, we are diving into altitude tents.​

We will cover:
​

• How simulated altitude tents work
• The claimed benefits of altitude tents for mountaineers
• What the evidence suggests 
• What climbers say anecdotally
• How to get the best results if you want to use one
• Potential drawbacks
• My personal opinion
• Good and not-so-good alternatives if you are looking for an edge at altitude
  ​

​Hypoxic Tents For Mountaineers 

How Simulated Altitude Tents Work

The process is pretty simple:

• You get into a sealed chamber (in this context, a tent)
• A generator pumps nitrogen into the chamber.
• This changes the percentage of oxygen you breathe with each breath.
• Breathing this air with less oxygen reduces your blood oxygen saturation (similar to what happens at high altitude.
  
  

The idea is that this will trigger adaptations that mimic natural altitude.

One important note: this simulated altitude is NOT the same as natural altitude.

At natural altitude, the percentage of oxygen stays the same. What changes is the air pressure. ​

Both these situations lower blood oxygen saturation, but through different mechanisms. Keep this in mind because this is an important distinction.
​

The Commonly Claimed Benefits of Altitude Tents For Mountaineers

There are countless claims out there on what a tent will do for you.

But the three big claims are :

• Altitude tents reduce the risk of altitude sickness
  
• Altitude tents can pre-acclimatise you
• Altitude tents improve endurance performance at altitude.
  
  

So what does the science say?

The Science Behind Altitude Training

The science of altitude training can be really confusing. People often present altitude tent research in very misleading ways...

There are three types of altitude:

1. Natural (terrestrial) altitude
2. Hypobaric altitude
3. Normobaric altitude
   
   

Natural/terrestrial altitude is real-world altitude (up on the mountain). This works, no question. If you can get exposure to this, this is highly recommended.

Hypobaric altitude involves changing the air pressure in a simulated environment. This has some promising evidence for reducing altitude sickness, helping with some pre-acclimatisation and improving endurance performance at high altitude.

But the problem here is that this is not what the public has access to (and is not what you will get from an altitude tend to hire/buy online).

Normobaric altitude is what altitude tents use. This involves changing the oxygen percentage but not the air pressure. And this is where the evidence gets inconsistent.

Many studies look great in the abstract (the short summary people often read at the top of the study). But when you read the details, you see major limitations:

Some studies show reduced altitude sickness risk. But they tested altitude sickness inside a normobaric environment, not on an actual mountain.

Some studies show improved endurance performance. But they tested performance at sea level. Or inside a normobaric chamber. Not on a real mountain.

Some companies cite studies about altitude training, which show all these great benefits. But the studies they are citing are on natural altitude, not the normobaric altitude that products are actually using...

It can get really confusing.

But that said, there does seem to be some evidence for some benefits that can be potentially useful.

These benefits can be from:
​

• Ventilatory adaptations
• Improved haematological adaptations (e.g. changes in the blood, like more red blood cells/haemoglobin)
  
  

Which sounds great! And could potentially be very useful for a mountaineer going to high altitude. ​

But to be clear, these are only pieces of the full acclimatisation puzzle. Even if you see these results, they would never equal 'complete acclimatisation'. And they would never guarantee a reduced risk of altitude sickness. 
​

Mountaineers Anecdotes and Experiences For Altitude Tents

Sports science can lag behind what people practice in the real world. And high-altitude research has many limitations (e.g. access/cost), which make it even harder. So, looking at anecdotal evidence can be valuable.

Even if there isn't rock-solid evidence for their benefits, many mountaineers are using altitude tents. Many report back positive experiences, and are big fans.

On top of this, many companies require these tents for people doing a 'fast acclimatisation climb'. And there are definitely people reaching the summit on these climbs! But on the other hand, there are plenty of people who are not...

There is a general 'vibe' in the mountaineering community that altitude tents help more for moderate altitude climbs (around the 4000m range).

So they may be useful for those who are only getting up to this high. Or, for those who are pushing higher and want to feel a bit more comfortable at these moderate altitudes (or, to give their body a headstart at these moderate altitudes, which would therefore have a better chance of handling the higher elevations). 
​

Best Practices for Using Altitude Tents

If you want to use an altitude tent, your main priority is exposure.

From what I have read, to see consistent results (with the adaptations we want for high altitude), you need a minimum exposure of 250 hours.

If you sleep 8 hours a night, that's about 4.5 weeks of using it every night.

For big mountain climbs (e.g. 6000-8000m), many hypoxic coaches recommend using tents for 6-8 weeks before an expedition.​

So to be clear, if you just do a few nights here and there, or just a couple of hours a week in a simulated altitude chamber, you will likely not get the adaptations you want for the mountain.

Beyond expsoure, getting the right ramp up in regards to 'simulated altitude' over time, and monitoring how the body is feeling and recovering is important. Most companies providing altitude tents will give guidelines for this.

​Or, if you want to take this a step further, there are some people who do specific 'hypoxic coaching' for mountaineers.

Note: If you are using an altitude tent, it is always a good idea to see a doctor and get your irons levels tested (as early as possible). Adequate iron is important for some of the adaptations you are chasing with a tent and low iron levels may limit your results (to a certain degree). So get tested and, if you are low, take early action to try and bring your levels up to normal. 
​

Potential Drawbacks of Altitude Tents

Beyond the potential benefits, there are some genuine drawbacks to altitude tents that any mountaineer should consider.

Sleep And Recovery

Altitude tents can impact both sleep and recovery. The generator has a certain amount of noise, and the tents can get hot and stuffy. Some people find they wake up more, or struggle to fall asleep, or just don't get quite as deep a sleep. This doesn't happen to everyone, but it is common.

If your sleep is impacted, your recovery will suffer.

In the final months before you climb, your training will be coming to a peak. You will be doing your longest/hardest training sessions. And you will likely be pushing the limits of what you can fit in and manage.

If you are under-recovering during your peak training, it can have some negative consequences:

At the most basic level, you may not be able to consolidate as many of the benefits from your training as possible.

On a more worrying level, under-recovering can put you at a higher risk of burnout or getting sick (which are the last things you want just before an expedition!).

That is not to say altitude tents will automatically cause you to under-recover, or get sick...

But it is a factor you need to consider.

Relationships

This is a big drawback which always seems to get glossed over...

If you have a partner (who you live with), sleeping in a tent for 4-8 weeks can add some serious strain to the relationship.

Because when you are leading into a big mountaineering expedition, there are already a few common 'challenges' to most relationships.

• You will be spending A LOT of hours training
  
  
• You will likely be sacrificing social events (to some degree)
  
  
• You will likely be spending weeks apart when you go to the mountains.
  
  

In the final months/weeks of training, this pressure only gets worse from things like:

• Extra training volume (so even less time to spend with each other)
  
  
• Accumulated fatigue from months of training (which can often lead to bad moods)
  
  
• Extra stress for yourself (from last-minute organisation of logistics, gear, finishing up work, etc.)
  
  
• Extra stress from your partner (who may be dealing with nerves about your safety on the mountain, or taking on a larger part of the housework or looking after the kids)
  
  

And even if you have the most supportive partner, stacking on 4-8 weeks of sleeping apart can be a genuine strain.

This issue seems to be always glossed over when people are talking about altitude tents - but it should be a serious thought for any mountaineer considering using one (at least, those who are living with a partner).

*This all may sound a bit dramatic, but I have had multiple occurences with mountaineers I have worked with who have gone through these exact struggles. 

Cost

Finally, there is cost. Hiring (or buying) a tent does require a significant financial investment. ​

Mountaineering is never a cheap sport (even more so when you are looking at big mountain expeditions) - so this needs to be considered. 
​

My Personal Opinion on Altitude Tents For Mountaineers

I personally do not recommend altitude tents for most mountaineers.

I don't actively discourage them. If a mountaineer I am working with wants to use one, I will support them. And I will do everything I can to make sure our training and programming support them through it all. But I do not specifically advocate for altitude tents.

Why?

I do not see enough consistent benefit to justify the drawbacks.

I would much rather people:

• Nail their training (and put their focus into following their programming with the best level of energy)
  
  
• Recover well
  
  
• Acclimatise traditionally on the mountain 
  
  

I fully understand that in some climbs (e.g. fast acclimatisation schedules), these are a requirement, and in that situation, definitely use them.

But if someone ever were tossing up between a fast acclimatisation schedule with an altitude tent, and a normal scheduled climb, I would recommend the normal acclimatisation schedule 100% of the time.

And if a mountaineer came to me asking how they can best prepare for a high-altitude climb, a tent wouldn't be something I would push for 98% of the time.

The small minority, in my opinion, who would get the most benefits from an altitude tent (with the least amount of drawbacks) would be a mountaineer who:

• Is single (or has their partner climbing next to them on the upcoming expedition)
  
  
• Has been through a structured training plan before and knows how their body/mind feels during a peak phase (and is confident they could stack on more 'stress' during this time with a tent)
  
  
• Is nailing their nutrition (and doing everything they can to support their energy and recovery through their food)
  
  
• Has relatively low life stress
  ​

In this situation, I would be much, much more confident advocating for an altitude tent for their preparations. ​

But that is just one coach's opinion. 
​

​Good Alternatives To Altitude Tents For Mountaineers

Even though I am not a massive advocate for altitude tents, I fully understand that many mountaineers going up to high altitudes want an edge.

They might be nailing their training, doing everything right there. But just wanting to do a bit more.

And if you think an altitude tent isn't quite right for you, what alternatives could you look at?

Well, I want to share a couple of things which might be worthwhile.

To be clear: when I am talking about 'alternatives', this is not meant to be a one-to-one replacement. What I am about to suggest will not do the same thing that altitude tents are claimed to do. They will not pre-acclimatise you. They will not make a direct difference to altitude. They would never be used to shorten an acclimatisation schedule.

But these are alternatives in the sense that if you want to explore something 'extra' on top of your training, which might give you an advantage for your high altitude expedition, these could be two good options.

Good Alternative #1: Respiratory Muscle Training

Respiratory muscle training (RMT) is essentially strength training for your breathing muscles. With this, you follow a very specific training protocol (with a particular respiratory training device) to strengthen your inspiratory breathing muscles.

This has some cool (potential) benefits for high altitude. In brief (I will go into detail on this in the future), respiratory muscle training has some evidence to suggest it can:

• Delay fatigue in the breathing muscles (which is common when exercising at high altitude)
  
  
• Delay the 'respiratory muscle metaboreflex' (essentially preventing blood from being pulled away from your working muscles to the lungs)
  
  
• Decrease dyspnea (e.g uncomfortable breathlessness) at high altitude.
  
  
• Increase blood oxygen saturation at high altitude.
  
  
• Improve processing speed and working memory during exercise at high altitude.
  
  

These are all potential benefits, and much more research needs to come out for us to 100% conclusively say a mountaineer will get these from RMT.

But here is why I am a big fan of respiratory muscle training for high altitude mountaineers:

The training protocol is realistic, with minimal drawbacks.

To get the desired results from respiratory muscle training, you do six minutes of training a day (three minutes in the morning, three minutes in the evening). You do this for about six weeks before your climb.

The only drawback is that you do need a specific respiratory training device to properly load up the breathing muscles (you cannot do this effectively by just breathing through one nostril or holding your breath).

Depending on what brand and model you get, these may cost you between $100-$200 (or more, if you get fancy).

For respiratory muscle training, in the best-case scenario, you could get all the above-mentioned benefits from the mountain.

In the worst-case scenario (if it did absolutely nothing for your high altitude performance and comfort), it would not impact your training, your recovery or your sleep. And it would be a minimal time investment.

This is why I consider it a good option.

Good Alternative #2: Working With A Dietitian Who Specialises In Mountaineers

Again, this is not a one-to-one replacement for the claimed benefits of an altitude tent. But if you are looking for an advantage at high altitude, this is a great place where a mountaineer can put their money and time.

Because so many mountaineers do not have a good handle on their nutrition (both for their training and the mountain).

So many mountaineers tend to undereat (and not get enough fuel to support their training, climbing, and recovery). And most mountaineers don't know hw to find the best balance of foods to support them.

By honing in on your nutrition with a specialist, you can ensure you are doing the right things with your nutrition to best support your energy, recovery, body composition and health (both in your training and when on the mountain).

And by working with a specialist who understands the needs, concerns and constraints of a high altitude mountaineer, you can ensure the advice is relevant for you and your situation. ​

If you want an edge for your high-altitude mountaineering, this is a great option. 
​

​'Not So Good' Alternatives for Altitude Tents

Finally, I want to cover some 'not so good' alternatives for altitude tend. A few things which I often see people recommend as alternatives, or good options for high altitude mountaineers, but which are not particularly great.

'No So Good' Alternative #1: Altitude Chambers

Simulated altitude training can be done in a tent, a chamber of with a mask (which is hooked up to a generator).

But, as we said before, if you want to get the best benefits from simulated altitude training, you need exposure time (hundreds of hours).

Altitude chambers will allow you to get exposure to this simulated environment, but only typically for a few hours a week (at most).

This might give you some positive results for sea level performance (or in some very particular aspects of fitness). But if you are specifically looking for adaptations that will help you in high altitude, this is not going to be enough time.

'Not So Good' Alternative #2: Elevation masks.

These used to be marketed as altitude masks.

A 'real' simulated altitude mask attaches to a generator that pumps nitrogen and changes oxygen percentage. These are possible to access (but fall into the same limitations as an altitude chamber).

Elevation masks are not this. Elevation mask restricts breathing (the feeling is similar to breathing through a straw).

Using these elevation masks does not change the oxygen percentage in your blood. They cannot in any way be related to altitude training. And the specific benefits they can bring do not relate very well to high-altitude mountaineers.

There is some evidence to see that these masks can help with respiratory muscle strength (which can be good!). But there are two big drawbacks here:

1. You have to wear the mask during your training sessions (which feels very uncomfortable and will limit your performance and training output during your sessions)
   
   
2. The resistance of the masks is not enough for an efficient and effective stimulus (you can get larger benefits, with less time and effort, by using a proper device)
   ​
   

These masks can have some benefits for certain athletes (and there are some specific markers of fitness they can improve). But they are more related to certain higher-intensity sports.

Want to learn more about these masks? You can check out this podcast and article: Elevation Masks.

'Not So Great' Alternative #3: Breath Hold Training

Breath-hold (also known as apnea training) has been around forever. There are some interesting potential benefits and adaptations people can get from this type of training.

But recently, some people have rebranded a particular method of breath-hold training as 'simulation of high altitude training'. In the mountaineering context, this is incredibly misleading...

Certain methods of breath-holding training can temporarily drop blood oxygen saturation (which is why people say it is a 'simulation' of high altitude).

For people who are living and training at sea level (and never needing to go up to natural altitude), this claim is fine.

But in the mountaineering context, this does not add up. (And I have seen people online saying that doing a few minutes of this a day will "pre-acclimaitise you" and "give you a headstart for high alititude").

Without even getting into the specifics of the claimed benefits (we will do that in the future), there is a very simple chain of logic which really makes me doubtful about the effectiveness of breath-hold training in the context of preparing for high altitude:

If altitude tends to require a minimum of 250 hours to get consistent results (and even then they do not fully pre-acclimatise you)...

And getting a few hours a week in a chamber is not seen as a long enough stimulus to be particularly worthwhile for a high altitude mountaineer...

How can a few minutes a day (at most) of reduced blood oxygen saturation from breath holds be expected to do anything significant for high altitude preparation?

Again, there might be some specific benefits you can get from this type of training. But as it relates specifically to preparing you for high altitude, it isn't a great option (at least, in my opinion). 
​

​Wrapping Up:

Hopefully, this gives you some good insights into hypoxic tents for high altitude mountaineers.

My opinion may change in the future. If there is stronger evidence that comes out on their benefits (consistently), I may be more of an advocate for them. ​

But for now, they have some potential benefits and some potential drawbacks. And the balance of these has formed my opinion. 

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