The BOLT Score For Hikers And Mountaineers

In this article and episode, we dive into the BOLT Score, a widely recommended test in the world of breathing training. We discuss what the BOLT Score measures, its relevance for hikers and mountaineers and if and how it should be used. 

​Many hikers and mountaineers are naturally drawn to breathing performance and breathing training (especially if you're heading up to high altitudes). And if you have ever gone down this rabbit hole before, you may have heard of the BOLT score.

There are many people talking about this online and sharing how using this test and improving this score can be useful for hikers and mountaineers.

Which is all well and good, but there is one big problem I see here.

There isn't often much context or nuance when this topic is talked about. And, more often than not, people get very carried away with all the amazing things improving this score can do (even though there might not be much evidence to support what they are saying).

So today, we are giving a bit of a rundown on this topic and, hopefully, giving a bit more context and nuance than what is usually presented on it.

We will cover:

• What the BOLT score is (and how to test it)
• Why people recommend this for hikers and mountaineers
• What this score is good to measure (and what it is not)
• How Hikers And Mountaineers Should Use The Bolt Score 

Breathing Training For Hikers And Mountaineers

What is the BOLT Score (And How To Measure It) 

BOLT stands for Body Oxygen Level Test.

It is recommended as a testing tool by breathing coaches around the world.

This test is very simple; it involves holding your breath after an exhalation, timing yourself until you feel the first definite urge to breathe.

So you would:
​

1. Take a normal breath in through your nose and allow a normal breath out through your nose.
2. Hold your nose with your fingers
3. Start your timer.
4. Time the number of seconds until you feel the first definite desire to breathe (or the first stress of your body urging you to breathe)
5. This isn't a 'max' test, but you just go up until you get the first need to breathe.
   
   

The number of seconds you get is your score.

The next step, which is usually recommended, is to take this score and reference it to a chart.​

The typical scoring goes:

• Under 10 seconds - you need A LOT of work (and doing specific breathing exercises will likely see 'dramatic' improvements to your health and exercise performance).
• 10-20 seconds - you need quite a bit of work (and improving will see very good improvements to your health, fitness, breathlessness, and sleep)
• 20-30 seconds -you are pretty good (but you can still see improvement in your health and fitness if you improve)
• 40+ - you are great! 

Why People Often Recommend The BOLT Score

Many people are interested in breathing training. However, improvements in breathing are hard to quantify (and improvements are usually very subjective).

On top of that, professional assessments on your breathing exist and are effective, but require appointments, money and access.

So the BOLT score can be a simple option that anyone can use, which doens't require much effort or money, and gives a clear number to measure and track.

That makes sense.

Some coaches, when presenting this, are measured and will say this score is a good way of gauging your tolerance to carbon dioxide, which can influence feelings of breathlessness during exercise, which is totally fair.

But all too often, people take this a bit too far. And they make some very bold claims about this score.

For example, people will say things like:
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• "A low BOLT score means you have 'dysfunctional breathing"
• "Improving your score will boost your physical performance, VO2 max, and endurance"
• "A better score improves sleep, mental focus, reduces anxiety, lowers blood pressure, and speeds recovery"
• "Improving your BOLT score will prevent altitude sickness and help pre-acclimatisation"
  
  

Which are some pretty big claims to make!​

So today, we are exploring these claims in a bit more detail than what is commonly presented: 

What Is The BOLT Score Useful For (For Hikers And Mountaineers)

Lets explore some of the claims:

Altitude Sickness And Pre-Acclimatisation

"Can improving your BOLT score reduce the risk of altitude sickness or pre-acclimatise you?"

No. There is zero evidence of this.

You could argue that some adaptations in your body, which help improve your BOLT score, could potentially help you at altitude...

But there is zero evidence to show that it is linked to altitude sickness or acclimatisation. Anyone saying or implying this is being really dishonest.

Dysfunctional Breathing

"If you have a low BOLT score, do you have dysfunctional breathing?"

No.

The 'dysfunctional breathing' link comes from a study suggesting that the BOLT score can serve as a screening tool.

But there are a few points which people always seem to miss here:
​

• The BOLT score alone was not seen to be an effective screen. Only when it was combined with a short questionnaire was it seen to have a good correlation as a screen
• Even with the attached questionnaire, this is not designed to 'diagnose' you with dysfunctional breathing. It is a 'screen' - which means, if you get flagged on it, it is a sign to go and get a proper assessment to look into it deeper.
• The article clearly says this is a 'sensitive screen' (and most people fail it), so if you fail, it isn't the end of the world (and it is only a sign to go and explore this further)
  
  

Ultimately, if anyone is saying, "if you have a low bolt score, you have dysfunctional breaching", they are doing you a disservice.

Exercise Performance

"Will improving my bolt score increase my V02 max, endurance or exercise performance?"

There is no direct evidence that shows there is a link to your BOLT score and V02 max, endurance or exercise performance.

The only two studies I have found that have looked at this:
​

• Saw no correlation in highly trained athletes (speed skaters)
• Saw no correlation in active students
  
  

You could definitely argue that logically improving your BOLT score could improve certain areas of exercise performance...

But there doesn't seem to be any direct evidence to support this.

Anyone making blanket statements about how improving your BOLT score will automatically improve your exercise performance is probably being hyperbolic.

Health

"Will improving my BOLT score improve my sleep, stress or health?"

I have not seen any evidence to link your BOLT score to sleep quality, concentration, mental focus, anxiety, stress recovery or blood pressure. 

Again, you could argue there is a chain of logic which might lead to some of these things... but there is no direct evidence to support any of this.

Carbon Dioxide Tolerance

This is the area in which this test makes sense.

Your drive to breathe is driven by carbon dioxide. When CO₂ builds up in your blood, your body senses it and triggers the urge to inhale.

A lower bolt score suggests your body feels the urge to breathe at lower CO₂ levels, meaning lower CO₂ tolerance.

A higher score suggests your body can tolerate higher CO₂ levels before triggering the urge to breathe.

So you can use this score as a way to track your progress if you are doing carbon dioxide tolerance training. ​

Want to learn more about carbon dioxide tolerance training? Check out this podcast episode: Carbon Dioxide For Hikers And Mountaineers 

How Hikers And Mountaineers Should Use The Bolt Score

Getting and tracking your BOLT score is not necessary for most hikers or mountaineers. You don't have to do it. I don't get my hikers or mountaineers to do it.

If you are interested in breathing training and are actively trying to improve your carbon dioxide tolerance, use it to track improvement.

Do not use the BOLT score to judge your breathing mechanics. If you are interested in this (and if you are 'dysfunctional' or not), go see a specialist who can assess you properly.

Do not use the BOLT score to assess your ability or improvement regarding exercise performance. If you want to assess this, there are hundreds of more relevant measures that will look at this directly.

Do not use the BOLT score to judge your readiness for altitude or risk of altitude sickness - it has no relevance to this.

Wrapping Up

The BOLT score is simple, cheap, and easy to use.

If you are interested in carbon dioxide tolerance, it can be useful.

Beyond that, the hype is probably overblown.

So make sure you use it in the right context.

Yours in trekking,

Rowan 

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