Breath Hold Training For High Altitude Mountaineers And Hikers

In this episode, we explore breath-hold training for high-altitude mountaineering and hiking, breaking down some of the claimed benefits of this breathing training method and exploring its relevance and effectiveness for high-altitude preparations.

Inside, we answer the questions:
​

• What is breath-hold training?
• Can breath-hold training be considered another form of altitude training?
• Does breath-hold training reduce the risk of altitude sickness?
• Can breath-hold training preacclimatise you?
• Is breath-hold training an effective way to improve your respiratory muscle strength?
• Is breath-hold training useful for improving carbon dioxide tolerance?
• How does breath-hold training affect the release of EPO (and how can that affect my fitness and preparations for high altitude)
• Does breath-hold training improve aerobic or anaerobic fitness? ​

Does Breath Hold Training Help Prepare For High Altitude?

​Today, we are talking about breath-hold training for high-altitude mountaineers and hikers.

This type of training is becoming more and more popular in the world of mountaineering and hiking. If you have ever explored the rabbit hole of breathing training before, you have probably come across this.

Now, the whole topic of breath-hold training or apnea training is a very murky subject.

It is very niche. There is not a huge amount of research (and even less so when looking at high altitude specifically). And the research that does exist is often conflicting.

There is no massive body of evidence clearly pointing one way or another (as is common in any niche subject).

And whenever we find one of these fields in the training world where the evidence is thin, it often becomes the wild west.

Because it is 'murky', we see people making very big claims about this type of training for hiking, mountaineering, endurance performance, and high altitude.

To give you some examples of this, here are a few direct quotes I have pulled from articles and videos on the subject:

• "Proven by published scientific research to increase hemoglobin concentration in your body"
• "Prepare your lungs and legs for exertion at high altitude"
• "This will get you more acclimated to less oxygen being available to our bodies"
• "In as small as 3 sessions of this, I have noticed it makes a huge improvement to my ability to perform at high altitude" 
• "Your body will make physiological adaptations, at no matter what elevation you are training, as if you were already at altitude" 
• "Breath-hold exercises will help improve respiratory muscle strength"
• "These exercises promote the strength and endurance of your respiratory muscles, and stimulate the release of erythropoietin (EPO), which boosts red blood cell production and enhances oxygen-carrying capacity."
• "One of the best ways to prepare your body for this type of exertion"
• "This can simulate altitude training at home" 
• "We demonstrate the breath holds that have the potential to help you pre-acclimatise or avoid altitude sickness entirely."
  
  

Those are some VERY big claims.

But when you actually dive into the research and look deeper, a lot of what is being said does not really stack up.

That does not mean breath-hold training has no benefits. That does not mean it has no place. But the way it's discussed is often hyperbolic.

The problem is that when everyone is saying the same thing over and over again, anyone who is interested in the subject only hears one side of the story.

They hear this is the new best thing in the world for high-altitude hikers and mountaineers. It will be your 'secret weapon'.

What they do not hear is context. They do not hear nuance.
They do not hear limitations.​

So today I want to zoom out and give a bit of a broader and more nuanced take.

What Is Breath Hold Training?

The origins of this idea come from observing free divers. Free divers go underwater and hold their breath for sport. Elite free divers show certain adaptations in their bodies from repeated breath-holding.

People looked at them and thought:

"If we could replicate some of these adaptations on land during exercise, that could be beneficial for other sports."

So the concept of breath-hold training involves combining exercise with breath-holds to try to produce some of these adaptations.

There are dozens of ways people approach this.

The main method promoted to hikers and mountaineers is holding your breath after an exhalation.

You breathe out. You hold.

Some people do this sitting in a chair. Some do it walking. Some progress to running or interval training.

(There are other variations, such as holding after inhalation or using hyperventilation first, but the hold after exhalation is the most commonly promoted in our world).

Now the basic idea is this.

If you hold your breath after a passive exhalation:

• Carbon dioxide builds up in your body
• Oxygen saturation drops

The increase in carbon dioxide is 'hypercapnia'.
The drop in oxygen is 'hypoxia'.

Together, they disturb the blood's acid-base balance. pH drops. This stimulates certain adaptations.

That is the theory.​

Now let us move into the big claims.

The Claimed Benefits Of Breath Hold Training For High Altitude Mountaineers And Hikers ​

Using Breath Holds For Altitude Training

A lot of people talk about breath-hold training as a way to prepare for high altitude. They claim it can be considered a form of altitude training, it can reduce the risk of altitude sickness, and it can pre-acclimate you.

In fact, when we are talking about breath-hold training, some people have coined an approach to this as 'simulation of high altitude training'

'Technically, in a general population context, you could argue that this name makes some sense because you are creating temporary hypoxia.

But in the mountaineering context, that terminology is VERY misleading.

Let me be clear.

• 'Simulation of High Altitude Training (breath holds)' does not equal Altitude Training (natural altitude)
• 'Simulation of High Altitude Training (breath holds)' does not equal 'Simulated Altitude Training (tents/chambers)
  
  

The names are very similar, but in no way does a mountaineer want to get this confused.

The names sound similar. The mechanisms are not the same. The impact is not the same. The results are not the same.

Let us zoom out for a second and talk about altitude training more broadly.

There are three main categories.

Number one is terrestrial altitude training. This is natural altitude. Going to the mountains. Living and/or training at natural high altitude.

Obviously, that is effective for preparing for altitude. If you have the opportunity for this in your preparations, it is the gold standard. But it is not accessible or practical for most people.

Number two is hypobaric altitude training. This simulates altitude by reducing air pressure in a sealed chamber. This closely mimics natural altitude, but it is not commercially accessible (and is typically limited to pilots, military or scientific research).

Number three is normobaric altitude training. This keeps air pressure the same but reduces oxygen concentration. This is what altitude tents, chambers, and masks use (and what is typically what mountaineers and hikers will use when doing 'simulated altitude training').

Now, when we look at normobaric simulated altitude training, there are some positive adaptations you can get. There is evidence showing some improvements in endurance and some potential benefits for altitude performance.

But here is the critical point.

To see consistent and meaningful adaptations for high altitude performance, the typical minimum effective dose is over 250 hours of exposure.

That usually means sleeping in an altitude tent for eight hours a night for four to five weeks.

Even then:

• It is not full acclimatisation
• It does not eliminate altitude sickness risk
  
  

So here is the problem:

If you need hundreds of hours in a hypoxic environment to see consistent results, and even then it is not full acclimatisation, how can minutes of hypoxia from breath holds be considered equivalent?

Yes, you can see a drop in blood oxygen saturation during breath holds.

Yes, technically, that is hypoxia.

But the magnitude and duration are not comparable to prolonged exposure.

There is one study looking at six weeks of breath-hold training that showed no change in altitude sickness symptoms.

It had limitations. It is only one study. But it certainly does not support the claim that breath-holding pre-acclimatises you or reduces altitude sickness risk.

In my opinion, breath holds can NOT be considered another form of altitude training in the mountaineering context.​

They are not a replacement for natural altitude. They are not equivalent to tents or chambers. They cannot be considered a pre-acclimatisation strategy.

Using Breath Holds For Respiratory Muscle Strength

Strengthening inspiratory breathing muscles can have potential benefits at altitude.

Research has shown that it may potentially:
​

• Delayed onset of premature fatigue of inspiratory muscles
• Delayed respiratory muscle metaboreflex onset (i.e. blood isn't pulled away from working muscles to the breathing muscles) 
• Improved clearance and tolerance to anaerobic metabolite products
• Decreased perception of dyspnea (breathlessness) 
• Increased SaO2 vValues
• Improved processing speed and working memory during exercise at altitude
  
  

*All of these have some evidence in a high altitude environment (though still needs more research)

This area is genuinely interesting.

But the tricky thing about our breathing muscles is that they are naturally strong! And to effectively strengthen them further, they need a significant amount of load to improve.

Evidence suggests that to effectively strengthen inspiratory muscles, you need around 30 per cent or more of your 'one repetition maximum' (of your inspiratory breathing muscles) as a training stimulus.

(And using less resistance may feel difficult, but it is not an effective training stimulus.

Most of the research achieving these results uses specific respiratory training devices that allow targeted and progressive loading.

It is hard to see that breath-holding will provide enough training stimulus to effectively reach this type of load (and progress it over time).

There is one study often cited showing improvements in respiratory muscle strength from breath-hold training.

But that study involved:
​

• Elite swimmers
• 3x 30-45 minute treadmill running sessions per week, doing repeated maximal breath holds (a lot of time and intensity)
• Close monitoring of hypercapnia levels with individual adjustments on breath holds to ensure that specific levels were reached.
  
  

This doesn't seem very practical for most hikers or mountaineers to incorporate (and the study doesn't seem to have been replicated).

There may be some benefit, but most of the evidence points towards the use of a respiratory training device as the standard for improving respiratory muscle strength.​

(Not to mention using a dedicated inspiratory training device requires MUCH less time and effort to see consistent results - with the typical training protocol involving 6 minutes per day, for 6 weeks). 

Using Breath Holds For Carbon Dioxide Tolerance Training

Carbon dioxide tolerance training is an interesting subject, and this is where breath-holding makes the most sense.

A very simplified breakdown of this:

Carbon dioxide is a normal part of breathing:

• During breathing, we inhale oxygen and breathe out carbon dioxide
• Our muscles use oxygen and produce carbon dioxide
• During exercise, we need more oxygen, and we produce more carbon dioxide

Carbon dioxide in the blood is one of the stimuli that affects our respiration. 

• When carbon dioxide builds up, this leads to quicker breathing, which then leads to less carbon dioxide (because we breathe it out)

Theory of Why More Carbon Dioxide Could Be Beneficial At High Altitude:

• An increase in our blood carbon dioxide leads to our hemoglobin (which carries the majority of oxygen in our blood) to 'dump' more oxygen (which is good for exercise!)
• Carbon dioxide can dilate (expand) our blood vessels.

Both of these, in theory, can be beneficial for both exercise and high altitude.

The idea of carbon dioxide tolerance training is that we expose the body and mind to the buildup of carbon dioxide. If we do this in a gradual and progressive way, we can allow the body to be less 'sensitive' to carbon dioxide (meaning, it will take longer for our breathing to speed up).

In theory, this has two big benefits:

1. You will be able to accumulate more carbon dioxide before you need to 'breathe it off' (which will positively affect your hemoglobin and blood vessels)
2. You will be better able to sustain slower/steadier breathing (which will lead to less anxiety, help you feel more comfortable, and, potentially, allow for better oxygenated blood).

In theory, this all sounds pretty good!

And it can be pretty safe to say that breath-hold training can be an effective method of improving carbon dioxide tolerance.

But saying this, there are a few big caveats to be aware of:

While the theory sounds good, there is currently no direct evidence linking carbon dioxide tolerance training to improvements in altitude performance, reduced risk of altitude sickness or better acclimatisation.

On top of this, well-trained endurance athletes frequently have lower chemosensitiviy (e.g. sensitivity to carbon dioxide) without any specific breath-hold training or other carbon dioxide tolerance training, which suggests that good endurance training will improve carbon dioxide tolerance regardless.

Breath Hold Training And EPO Release

EPO (erythropoietin) is a hormone that stimulates the bone marrow to create red blood cells, which carry oxygen to tissues. 

One claim about breath holds is that they will increase EPO levels (and therefore, will increase red blood cells, hemoglobin, and endurance performance).

Breath holds have been shown to increase EPO levels temporarily.

One study (which always gets quoted) saw an increase in EPO by 24% after a series of breath holds (which peaked after about three hours and returned to baseline shortly after).

So the theory is, if you regularly do breath holds and continually spike your EPO levels, it will lead to an increase in red blood cells (and your oxygen-carrying capacity in the blood).

But this is where this theory falls apart:

Many studies on intermittent altitude training (simulated altitude training in a tent, chamber or mask) show an increase in EPO.

This is common.

What is NOT common this rise in EPO, always leading to a rise in hematological response (e.g. turning into a change in the red blood cells/hemoglobin).

Studies of 'traditional' simulated altitude training have examined this and concluded that changes in oxygen-carrying capacity in the blood are determined by the severity and time spent in hypoxia.

This puts some doubt as to whether spending seconds/minutes of hypoxia will be enough of a stimulus to see actual change to the red blood cells or hemoglobin. ​

So while it is true that breath holds can increase EPO, there doesn't seem to be any strong evidence that this will automatically lead to any further adaptations that will help a high altitude mountaineer or hiker.

Breath Hold Training And Aerobic Fitness

A common claim is that breath-hold training will improve aerobic capacity and aerobic fitness.

Aerobic capacity is the single most important aspect of fitness for a high altitude mountaineer or hiker, so this is important.

*To be clear, a higher aerobic capacity does not automatically mean a reduced risk of altitude sickness. But better aerobic capacity will lead to reduced fatigue and exhaustion (which are risk factors for altitude sickness) and better performance on the mountain.

There are some individual studies that show breath holding can have positive benefits to help aerobic capacity.

But the body of evidence does not support this.

One systematic review on the subject did not see any consistent benefits from breath-hold training for aerobic performance.

It did see some potential benefits for 'anaerobic performance (e.g. higher intensity), which might be relevent for high intensity intermittent sports (e.g. team sports, combat sports, racket sports) or for those who are doing higher intensity continuous sports (such as sprinting in swimming, athletics or cycling).

But high-altitude mountaineering and hiking are not anaerobic activities; they are not high-intensity sports or races, so these particular benefits are not particularly relevant in this context. ​

Are Breath Holds An Effective And Relevant Training Method For High Altitude Mountaineers?

Breath-hold training is an interesting area of training.

It might be beneficial to do so, but a lot of the claims commonly made about it are dubious.

Breath-hold training does not simulate high altitude training (in the mountaineering and hiking context), pre-acclimatise you or do anything to reduce altitude sickness.

Breath-hold training does not seem like it will reliably increase your aerobic fitness or be an efficient method of improving your respiratory muscle strength.

Applying Breath Hold Training As A Mountaineer (My View)

I don't think most mountaineers should be doing breath-hold training.

It isn't the magic technique many people make it out to be, and I believe your time, effort and concentration would be much better served focusing on other areas of training.

However, if you really want to explore this in your training, please make sure you are smart about it.

A few important notes:

Always make sure you are following a structured and progressive training program already (where you will get the majority of your performance increases)

Never think breath-hold training will replace (or speed up) an acclimatisation schedule.

Never think breath-hold training is a good thing to "replace your cardio" with

Never let breath-hold training negatively impact your other 'normal' training sessions (e.g. take up so much time or energy that it affects or limits your other sessions)

If adding this into your training week, I would usually recommend keeping them to:
​

• Your warm-ups (e.g., do some breath holds while going through a slow cardiovascular warm-up)
• During walking training sessions (e.g. neighbourhood walking, loaded pack walking or something similar where this can easily be incorporated)*​

*Just don't do this while actually hiking or on any type of terrain that requires thought/stability (in case you get dizzy).

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