Science / Functional Breathing Technique / Measure Your Bolt Score

Measure your BOLT Score and Reduce Breathlessness During Exercise

by Patrick McKeown

The Body Oxygen Level Test (BOLT): Easy Steps to Assess and Improve Your Breathing

The BOLT score (Body Oxygen Level Test) is a subjective measure of breathlessness. It gives feedback on functional breathing and exercise tolerance.

In this chapter you will learn:

  • How to hold your breath to measure your BOLT score
  • Why a higher BOLT score reduces the feeling of breathlessness
  • How to increase your BOLT score for better health and exercise performance
Measure your BOLT Score and Reduce Breathlessness During

As far back as 1975, researchers noted that the length of time of a comfortable breath hold can be used to determine relative breathing volume during rest, and breathlessness during physical exercise [1,2].

The Body Oxygen Level Test (BOLT), which involves an easy breath hold after exhalation, is a useful and accurate way to measure this relative breathing volume.

The ideal BOLT score for a healthy adult is 40 seconds. In the book, Exercise Physiology: Nutrition, Energy, and Human Performance by William McArdle and colleagues, the authors observe: “If a person breath holds after a normal exhalation, it takes approximately 40 seconds before the urge to breathe increases enough to initiate inspiration” [3].

The lower your BOLT score in seconds, the greater your breathing volume is likely to be. The greater your breathing volume, the more breathlessness you will experience during exercise.

How to measure your breathing using the BOLT score

To get an accurate measurement, it’s best to rest for ten minutes before measuring your BOLT score. Read the instructions carefully first. And have a timer to hand. On a day-to-day basis, we recommend taking the test first thing in the morning, but if you’re ready to try now, go ahead.


  • Take a normal breath in through your nose and allow a normal breath out through your nose.
  • Hold your nose with your fingers to prevent air from entering your lungs.
  • Start your timer.
  • Time the number of seconds until you feel the first definite desire to breathe, or the first stresses of your body urging you to breathe. These sensations may include the need to swallow, or a constriction of the airways. You may also feel the first involuntary contractions of your breathing muscles in your abdomen or throat, as your body gives the message to resume breathing. The BOLT is not a measurement of how long you can hold your breath, but simply the time it takes for your body to react to a lack of air.
  • Release your nose, stop the timer, and breathe in through your nose. Your inhalation at the end of the breath hold should be calm.
  • Resume normal breathing.

What will my BOLT score be?

Many people begin with a low BOLT score. In people with asthma, anxiety, and panic disorder, the BOLT score may only be 10 to 15 seconds. If your BOLT score is low, don’t worry. Even elite athletes often begin with a low BOLT score. The exercises in the OA™ quickly help you improve.

The BOLT score is influenced by several factors:

  • Chemosensitivity to carbon dioxide (CO2)
  • Constriction in the airways or lungs (narrow airways impact breath-hold time)
  • How uncomfortable the diaphragm feels during the breath hold
  • Anxiety and other psycho-emotional influences like fear of suffocation

If you have a breathing pattern disorder, you won’t be able to hold your breath for long. But with daily practice of breathing exercises, breathing will normalize. Your breathing rate will slow too. When your BOLT score is 40 seconds, the typical breathing rate is 8 to 10 breaths per minute.

How your BOLT score relates to breathlessness during sports

The first time you measure your BOLT, you may be surprised to find your score is lower than expected. But remember, even elite athletes can have a low BOLT score! Your BOLT score can easily be improved with a series of simple breathing exercises that incorporate into your existing way of life or exercise regime.

Your BOLT score in seconds — what to expect

BOLT is below 10: Your everyday breathing is noisy, irregular, and labored. You sigh or yawn a lot and sleep is disrupted, leaving you fatigued. Breathing exercises for breathlessness will dramatically improve your health and performance.

10-20: Your breathing may be compromised by a blocked nose, wheezing, or coughing. Your sleep is disrupted. Your energy and concentration are poor. Breathing exercises to increase the BOLT score will improve sleep quality, reduce breathlessness, and enhance health and fitness.

20-30: Your normal breathing is quiet, calm, and effortless. A BOLT score of around 20 seconds is good. But there are benefits for health and fitness if you can improve it even more.

If you exercise regularly at a moderate intensity, it’s normal for your starting BOLT score to be around 20 seconds. Each time your BOLT score increases by five seconds, you will feel better. You’ll have more energy and your breathlessness during physical exercise will lessen.

By practicing the breathing exercises, you will reduce your sensitivity to CO2. You will see a progressive increase in your BOLT score. And you will “reset” the breathing center in your brain, meaning less breathlessness during rest and exercise. The aim of the OA™ program is to increase your BOLT score to 40 seconds, and this can be realistically achieved.

Improving your BOLT score is an important key to attaining greater physical endurance too. When your tolerance to carbon dioxide improves, you can achieve a higher VO2 max and enhance performance. The Oxygen Advantage® program is all about increasing your BOLT score and maximizing your potential!

How to increase your BOLT score

It’s a breath hold after the exhalation — here’s why

When someone tells you: “Hold your breath,” the normal instinct is to first take a big breath in. But breath holding after inhalation is an unreliable way to test the breathing. Lung capacity differs from one person to the next. And some people are much more competitive than others!

How does the Body Oxygen Level Test (BOLT) work?

Scientists have shown that breath hold time can be used to measure sensitivity to carbon dioxide (CO2). When you hold your breath, you prevent oxygen from entering your lungs. At the same time, you prevent excess carbon dioxide from being expelled into the atmosphere. As your breath hold continues, carbon dioxide accumulates in your lungs and blood. Oxygen levels slightly decrease.

CO2 provides the main stimulus to breathe in. As CO2 increases in your lungs and blood, your brain reacts, prompting your breathing muscles to begin breathing. This means that the length of your comfortable breath hold is influenced by how much carbon dioxide you can tolerate —your “ventilatory response” to carbon dioxide [1].

When you have a strong ventilatory response to carbon dioxide, you’ll reach your threshold sooner. You’ll have a shorter breath hold time. When you have a higher tolerance and reduced ventilatory response to carbon dioxide, your breath hold will be longer. A low BOLT score just indicates that your breathing receptors are especially sensitive to carbon dioxide. Your breathing volume will be larger, as your lungs work to remove carbon dioxide. You’ll be in a sort of vicious cycle, in which you’re habitually breathing more air than your body needs, yet you feel constantly breathless.

The good news is, you can use the breathing exercises in the OA™ program to normalize tolerance to carbon dioxide. When your tolerance to CO2 is normal, your BOLT score will be higher. You will be able to maintain calm breathing during rest, and lighter breathing during physical exercise.

The link between your BOLT score and asthma symptoms

Breath-hold measurements have been used to study the onset and endurance of breathlessness (dyspnea) and asthma symptoms [4,5]. The result that comes up again and again is that the lower the breath hold time, the greater the likelihood of breathlessness, coughing, and wheezing, during rest and exercise.

Continue learning

References and notes:

  1. Stanley et al. concluded that, “The breath hold time/partial pressure of carbon dioxide relationship provides a useful index of respiratory chemosensitivity.”

Stanley, N.N.,Cunningham, E.L., Altose, M.D., Kelsen,S.G., Levinson, R.S., and Cherniack, N.S. Evaluation of breath holding in hypercapnia as a simple clinical test of respiratory chemosensitivity. Thorax.1975;30():337-343

  1. Japanese researcher, Nishino, acknowledged breath holding as one of the most powerful methods to induce the sensation of breathlessness, stating that the breath hold test, “gives us much information on the onset and endurance of dyspnea (breathlessness).” This paper notes two different breath hold tests as providing useful feedback on breathlessness. According to Nishino, because holding of the breath until the first definite desire to breathe is not influenced by training effect or behavioral characteristics, it provides a more objective measurement of breathlessness.

Nishino T. Pathophysiology of dyspnea evaluated by breath-holding test: studies of furosemide treatment. Respiratory Physiology Neurobiology.2009 May 30;(167(1)):20-5

  1. McArdle W, Katch F, Katch V. Exercise Physiology: Nutrition, Energy, and Human Performance. 1st ed. North American Edition. Lippincott Williams & Wilkins; Seventh, (p289) (November 13, 2009)
  1. The Department of Physiotherapy at the University of Szeged, Hungary conducted a study that investigated the relationship between breath hold time and physical performance in patients with cystic fibrosis (CF). Eighteen patients with varying stages of cystic fibrosis were studied to determine the value of the breath hold time as an index of exercise tolerance. The breath hold times of all patients were measured. Oxygen uptake (VO2) and carbon dioxide elimination was measured breath-by-breath as the patients exercised. The researchers found a significant correlation between breath hold time and VO2 (oxygen uptake), concluding that, “The voluntary breath-hold time might be a useful index for prediction of the exercise tolerance of CF patients.” To take this one step further, it makes sense that increasing the BOLT of patients with CF corresponds to greater oxygen uptake and reduced breathlessness during physical exercise.

Barnai M, Laki I, Gyurkovits K, Angyan L, Horvath G. Relationship between breath-hold time and physical performance in patients with cystic fibrosis. European Journal Applied Physiology.2005 Oct;(95(2-3)):172-8

  1. Results from a study of 13 patients with acute asthma concluded that the magnitude of breathlessness, breathing frequency and breath hold time was correlated with severity of airflow obstruction and, secondly, that breath hold time varies inversely with the magnitude of breathlessness when it is present at rest. In other words, the lower the breath hold time of asthmatics, the greater the breathing volume and breathlessness.

Pérez-Padilla R, Cervantes D, Chapela R, Selman M. Rating of breathlessness at rest during acute asthma: correlation with spirometry and usefulness of breath-holding time. Rev Invest Clin.1989 Jul-Sep;(41(3)):209-13

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