How to Measure Your BOLT Score

The Body Oxygen Level Test (BOLT) is a simple breath-hold test from the Oxygen Advantage Method that gives you direct feedback on your breathing volume, CO2 tolerance, and breathlessness during exercise. 

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

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, the greater your breathing volume is likely to be. The greater your breathing volume, the more breathlessness you will experience during exercise.

In this article you will learn how to measure your BOLT score, what your result means, and how to improve it for better health and exercise performance.

How to Measure Your BOLT Score

For an accurate measurement, rest for ten minutes before testing. Have a timer to hand. On a day-to-day basis, we recommend taking the test first thing in the morning.

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 to prevent air from entering your lungs.
3. Start your timer.
4. Time the number of seconds until you feel the first definite desire to breathe, or the first signs of your body urging you to breathe. These may include the need to swallow, a constriction of the airways, or the first involuntary contractions of your breathing muscles in your abdomen or throat. 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.
5. Release your nose, stop the timer, and breathe in through your nose. Your inhalation at the end of the breath hold should be calm.
6. Resume normal breathing.

Why the BOLT Is a Breath Hold After Exhalation

When someone tells you to 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 breathing.

Lung capacity differs from person to person, and some people are more competitive than others. Holding after a normal exhalation removes these variables and gives a consistent, objective measurement.

How Does the BOLT Score 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 and prevent excess carbon dioxide from being expelled.

As the breath hold continues, CO2 accumulates in your lungs and blood, and oxygen levels slightly decrease.

CO2 provides the main stimulus to breathe. As CO2 increases in your lungs and blood, your brain reacts and prompts your breathing muscles to begin breathing.

The length of your comfortable breath hold is therefore directly influenced by how much carbon dioxide you can tolerate, your ventilatory response to CO2 [1].

When you have a strong ventilatory response to CO2, you reach your threshold sooner and your breath hold is shorter.

When you have a higher tolerance and reduced ventilatory response, your breath hold is longer.

A low BOLT score indicates that your breathing receptors are especially sensitive to carbon dioxide. Your breathing volume will be larger as your lungs work to remove CO2.

You end up in a cycle of habitually breathing more air than your body needs, yet feeling constantly breathless.

The Oxygen Advantage breathing exercises normalize tolerance to CO2. When your tolerance to CO2 is normal, your BOLT score will be higher, and you will be able to maintain calm breathing during rest and lighter breathing during physical exercise.

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 score is low, do not worry. Even elite athletes often begin with a low BOLT score. The Oxygen Advantage exercises 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 will not be able to hold your breath for long. But with daily practice of breathing exercises, breathing will normalise and your breathing rate will slow. When your BOLT score reaches 40 seconds, the typical breathing rate is 8 to 10 breaths per minute.

Your BOLT Score in Seconds: What to Expect

Below 10 seconds: Your everyday breathing is noisy, irregular, and laboured. 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 to 20 seconds: 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 to 30 seconds: Your normal breathing is quiet, calm, and effortless. A BOLT score of around 20 seconds is good, but there are significant benefits for health and fitness if you can improve it further.

If you exercise regularly at a moderate intensity, it is 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 will have more energy and your breathlessness during physical exercise will lessen.

40 seconds: This is the target. By practising the breathing exercises, you will reduce your sensitivity to CO2 and progressively increase your BOLT score. You will reset the breathing centre in your brain, resulting in less breathlessness during rest and exercise. When your BOLT score reaches 40 seconds, breathing is light and slow during rest and moderate exercise, and the nervous system is well balanced.

Improving your BOLT score is also an important key to greater physical endurance. When your tolerance to carbon dioxide improves, you can achieve a higher VO2 max and enhance performance.

How Your BOLT Score Relates to Breathlessness During Sport

The BOLT score is not just a health indicator. It directly predicts your breathlessness during physical exercise.

The first time you measure your BOLT, you may be surprised to find your score is lower than expected. Even elite athletes can have a low BOLT score.

Breath-hold measurements have been used extensively to study the onset and endurance of breathlessness (dyspnoea) 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.

For athletes, a BOLT score below 20 seconds typically corresponds to disproportionate breathlessness during moderate-intensity exercise. A score above 30 seconds generally reflects efficient breathing patterns, good CO2 tolerance, and better endurance.

Improving your BOLT score is one of the most practical steps you can take to reduce breathlessness and improve athletic performance across all sports.

How to Increase Your BOLT Score

Your BOLT score can be improved with a series of simple breathing exercises that integrate into your existing lifestyle or exercise routine. The key practices are:

• Nasal breathing during rest, sleep and low-intensity exercise — the nose adds natural resistance and trains CO2 tolerance over time
• Paced breathing at 4.5 to 6.5 breaths per minute to activate the parasympathetic nervous system and reduce breathing volume
• Breath-light exercises — breathing slightly less than your normal volume to gently and progressively raise CO2 tolerance
• Breath hold exercises after exhalation during walking or light activity to simulate altitude training and build CO2 tolerance
• Using MyoTape during sleep to maintain nasal breathing overnight, reducing nocturnal over-breathing

With consistent practice, most people see meaningful improvement in their BOLT score within a few weeks. The Oxygen Advantage app includes guided breathing exercises with a breath pacer to support your practice. Download the free app.

The Link Between Your BOLT Score and Asthma

Breath-hold time has been used clinically to assess breathlessness severity and airflow obstruction in asthma. Studies confirm that the lower the breath-hold time, the greater the breathing volume and the more severe the breathlessness [4,5].

For every 5-second increase in BOLT score, you can expect a noticeable reduction in exercise-induced asthma symptoms. Restoring full-time nasal breathing and reducing breathing volume are the two most effective steps for people with exercise-induced asthma.

Start Improving Your Breathing with Oxygen Advantage

The BOLT score is the foundation of the Oxygen Advantage method. It is the starting point for understanding your breathing, tracking your progress, and connecting your breathing patterns to your health, sleep, and athletic performance.

To learn the OA method for yourself, please see our online breathing course, become a certified breathwork instructor, or find an Oxygen Advantage instructor near you.

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 NN et al. Evaluation of breath holding in hypercapnia as a simple clinical test of respiratory chemosensitivity. Thorax. 1975;30:337-343.
2. Nishino acknowledged breath holding as one of the most powerful methods to induce breathlessness, and noted that holding the breath until the first definite desire to breathe is not influenced by training effect or behavioural characteristics, making it a more objective measurement of breathlessness. Nishino T. Pathophysiology of dyspnea evaluated by breath-holding test. Respir Physiol Neurobiol. 2009;167(1):20-5.
3. McArdle W, Katch F, Katch V. Exercise Physiology: Nutrition, Energy, and Human Performance. 7th ed. Lippincott Williams and Wilkins. 2009. p289.
4. Researchers at the University of Szeged, Hungary, studied 18 patients with varying stages of cystic fibrosis and found a significant correlation between breath-hold time and VO2 (oxygen uptake), concluding that voluntary breath-hold time is a useful index for predicting exercise tolerance. Barnai M et al. Relationship between breath-hold time and physical performance in patients with cystic fibrosis. Eur J Appl Physiol. 2005;95(2-3):172-8.
5. A study of 13 patients with acute asthma found that breath-hold time varies inversely with the magnitude of breathlessness, confirming that the lower the breath-hold time, the greater the breathing volume and breathlessness. Pérez-Padilla R et al. Rating of breathlessness at rest during acute asthma: correlation with spirometry and usefulness of breath-holding time. Rev Invest Clin. 1989;41(3):209-13.