Measure Your Breathing Volume Capacity

One of the primary determinants of how fast and how long you can run without stopping is your lung capacity. Nearly every runner has found breathlessness to be the limiting factor in running faster at one time or another, so improving your lung capacity and aerobic breathing can have significant performance benefits for distance runners.

However, as important breathing metrics and lung capacity are for runners, we rarely do anything to measure or monitor changes and improvements in our breathing.

Fortunately, the BOLT Score Test is a practical way to measure your breathing volume, which can help you chart your aerobic fitness progress from your training.

Performing the BOLT Test is simple, and can be a great way to quantify improvements in your cardiovascular fitness. In this guide, we will cover how to do the BOLT Score test, how to interpret BOLT scores, and why you should care.

We will look at:

  • What Is the BOLT Score Test?
  • How Does the BOLT Score Test Work?
  • How the BOLT Score Test Works
  • Why Does Your BOLT Score Matter?
  • What Is a Good BOLT Score?
  • How to Increase Your BOLT Score

Let’s get started!

What Is the BOLT Score Test?

The BOLT Score Test, which stands for the Body Oxygen Level Test, is a breathing assessment popularized by Patrick McKeown, the creator of Oxygen Advantage which measures your relative breathing volume during rest as well as breathlessness during exercise.

While it’s natural to assume that a test that’s related to respiration and breathing would involve an assessment of how long you can hold your breath, the BOLT Test is not a measurement of how long you can hold your breath per se, but of how long it takes your body to react to a lack of air coming in.

According to McKeown, the scientific rationale for the BOLT Score Test dates back to 1975 when exercise physiology researchers observed that the length of time individuals could comfortably hold their breath before feeling the urge to breathe was an effective and practical test to determine relative breathing volume during rest and breathlessness during exercise.

And thus, the BOLT Score Test was born.

A sign next to a yoga mat and bed that says inhale exhale.

How Does the BOLT Score Test Work?

When you do breathing tests that involve measuring how long you can hold your breath, various factors other than just your lung volume and function come into play, which can conflate your results.

For example, someone who has greater willpower or motivation can push through longer than someone whose tidal volume and lung function may be just as good but who doesn’t feel like persevering through the same level of discomfort.

In this scenario, the differences in motivation and willpower can affect the results. When performed properly, the BOLT Test circumvents these types of variables.

With the BOLT Score Test, the time the measurement stops should be taken as soon as the first urge to breathe is felt.

Therefore, as long as you are being honest with yourself and the sensations you are feeling, rather than being competitive and trying to push through as long as possible, you can get a more accurate assessment of your relative breathing volume and breathlessness during physical activity.

A woman performing the BOLT Score test by holding her breath and covering her nose.

How To Do the BOLT Test

Performing the BOLT Score Test is simple and requires no equipment aside from a stopwatch, though, in a pinch, you can try to count seconds in your head.

Before doing the BOLT Score Test, you should rest quietly for at least 10 minutes, avoiding any physical exertion.

  1. Sit upright in a comfortable position.
  2. Take a normal breath in and out through your nose.
  3. As soon as you’ve exhaled through your nose, pinch your nose to prevent any air from entering your lungs and start the timer.
  4. Keep the timer running while you hold your nose and do not breathe.
  5. As soon as you feel the first sensation that your body wants you to breathe, stop the timer. Sensations you might feel include involuntary contractions of the diaphragm, the desire to swallow, a constriction of the airway, or a mental urge to resume breathing.
  6. The BOLT Test is now over, and you should let go of your nose and resume normal breathing.

Note that because you aren’t holding your breath even a second longer than your body would want you to take a breath, your first inhalation after the BOLT Test is over should be completely relaxed and normal.

If you feel like you’re gasping or taking a big breath, you pushed past the point of the first sensations of breathlessness and your BOLT score will be inaccurate.

A man with his eyes closed breathing calmly.

How the BOLT Score Test Works

When we breathe, we inhale air that has oxygen for our lungs to extract and use, and we exhale air that has a higher concentration of carbon dioxide. Carbon dioxide can be seen as the waste product of respiration.

Any time you hold your breath, you prevent this gaseous cycle, so oxygen levels in the lungs and blood decrease slightly while carbon dioxide levels increase.

Studies show that carbon dioxide concentration is the primary stimulus for breathing.

Therefore, Your BOLT Score Test score or the length of time you can hold your breath before feeling the desire to inhale is dependent upon your ventilatory response to carbon dioxide or the concentration of carbon dioxide your body can tolerate.

The more sensitive you are, or the stronger your ventilatory response, the quicker your carbon dioxide threshold will be met and the shorter your hold time will be. This will result in a lower BOLT score.

The converse is also true: the better your tolerance to carbon dioxide and the more minimal your ventilatory response to carbon dioxide, the longer it will take to feel the urge to breathe and the higher your BOLT Score Test score will be.

A woman out of breath from running with her hands on her knees.

Why Does Your BOLT Score Matter?

So, why does any of this matter? How does your sensitivity to carbon dioxide affect your athletic performance as a runner?

As mentioned, a lower BOLT score indicates that your breathing receptors are especially sensitive to carbon dioxide. Practically, this means that your breathing volume will be greater or your respiration rate will be faster because the threshold by which the lungs are being signaled to work to remove any excess carbon dioxide by breathing is quite low.

For example, using simple numbers that have no physiological bearing but just to make a point, if your carbon dioxide tolerance is only 20%, it would mean that your lungs would be triggered to breathe harder and faster any time carbon dioxide levels in the blood or lungs would rise above 20%.

If, however, your tolerance to carbon dioxide is higher and your ventilatory response is less sensitive—say, 30%, you’ll be able to carry on with normal breathing (not huffing and puffing or breathing super fast) at higher intensities (relative to the individual with lower tolerance to carbon dioxide) during exercise, where carbon dioxide levels naturally increase.

One study found that breath-hold time correlates with VO2 max and anaerobic threshold.

A woman doing breathing exercises by covering one notril.

BOLT Score Meaning

The lower your BOLT score, the more breathlessness you will experience during exercise because your body is more sensitive to carbon dioxide. This means you’ll be breathing more to expel even small excesses of carbon dioxide.

What Is a Good BOLT Score?

Of course, any sort of test is only valuable when you know how to interpret the results. The BOLT score is simply the number of seconds you lasted before you felt the first inkling to breathe.

According to The Oxygen Advantage, a good BOLT score is 40 or above. However, many athletes start out with BOLT scores around 20, so if you are well below 40, don’t feel discouraged.

You can increase your BOLT score and reduce your sensitivity to carbon dioxide with breathing exercises.

A woman out of breath from running.

How to Increase Your BOLT Score

Much like how strength training makes your muscles stronger, you can gradually increase your BOLT score with breathing exercises like the Wim Hoff method, breathing through your nose, and box breathing.

For example, try performing a simple box breathing exercise a few times a day:

Inhale for 4 seconds, hold the breath for 4 seconds, exhale for 4 seconds, and hold completely exhaled for 4 seconds.

Box breathing can also be used to reduce anxiety, and it can help your body get better at breathing more efficiently.

High altitude training may also increase your oxygen-carrying capacity, which can reduce breathlessness during exercise.

As runners, we just love our data, don’t we?

The BOLT test is just another test to tack on to the list of challenges we make ourselves face to track our improvement and work towards our peak performance.

If you are interested in seeing how you stack up with your fitness, you can take a crack at the Cooper Fitness Test or the Army Combat Fitness Test!

Or, you may want to sneak in a lifestyle challenge with The 75 Hard Challenge. Good luck!

A woman looking toward the trees with her arms spread wide.

Amber Sayer

Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, and contributes to several fitness, health, and running websites and publications. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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