Introducing the BOLT (Body Oxygen Level Test): A Simple Guide to Understand and Boost Your Breathing

The BOLT score, your personal breathlessness indicator, is a fascinating and user-friendly method to gauge your breathing efficiency. Not only does it provide insights into your everyday breathing habits, but it also tells you about your body’s ability to tolerate physical activity. Take the test and discover more about your breathing.

In 1975, scientists found that the duration one can comfortably hold their breath can be used to evaluate resting breathing volume and breathlessness during physical activity [1,2].

The Body Oxygen Level Test (BOLT), as simple as holding your breath after you exhale, is a reliable tool to assess this relative breathing volume.

For a fit adult, the ideal BOLT score is 40 seconds. In their book, “Exercise Physiology: Nutrition, Energy, and Human Performance,” William McArdle and his colleagues note that “After a normal exhalation, it typically takes around 40 seconds before the urge to breathe gets strong enough to trigger inhalation” [3].

Here’s something to remember: the lower your BOLT score (measured in seconds), the more likely you are to have a higher breathing volume. And the higher your breathing volume, the more likely you feel breathless during exercise.

How to measure your breathing using the bolt score

For the most accurate results, resting for ten minutes is ideal before calculating your BOLT score. Ensure you have the instructions clearly understood and have a timer ready. I suggest making the test a morning ritual, but if you feel eager to try it out right now, feel free!


Here’s your step-by-step guide:

  1. Initiate the process by taking a standard breath in through your nose, followed by a regular breath out through your nose.
  2. Use your fingers to hold your nose, ensuring no air slips into your lungs.
  3. Get your timer started!
  4. Keep a note of the seconds that pass until you experience the first undeniable urge to breathe or the initial signs of your body insisting that you need to breathe. These signs might be a necessity to swallow or tightening of your airways. You may even notice the first involuntary movements of your breathing muscles in your abdomen or throat, signalling your body’s desire to restart breathing. Remember, BOLT isn’t about how long you can withhold your breath but rather the time it takes for your body to respond to air deprivation.
  5. Once you feel these signs, let go of your nose, stop the timer, and breathe in through your nose. The inhalation following the breath hold should be calm.
  6. Continue with your normal breathing pattern.

Give it a go, it’s easier than you think!

What does my BOLT score mean?

It’s quite common for individuals to start off with a low BOLT score. For those dealing with conditions like asthma, anxiety, or panic disorder, the initial BOLT score might be just around 10 to 15 seconds. If you find yourself in the same boat with a low score, don’t fret. Interestingly, even some top-tier athletes kick off with a low BOLT score. The exercises in the OA™ program are designed to swiftly guide you to improvement.

Several factors can affect your BOLT score, including:

  • Your body’s chemosensitivity to carbon dioxide (CO2)
  • Any narrowing or constriction in your airways or lungs (this can influence your breath-hold duration)
  • The level of discomfort your diaphragm experiences during the breath hold
  • Psychological and emotional factors, like anxiety or fear of suffocation

If you’re dealing with a breathing pattern disorder, it might be challenging to hold your breath for extended periods. But don’t lose heart, regular practice of breathing exercises can normalise your breathing over time. As your breathing rate gradually slows down, your BOLT score will rise. For instance, when your BOLT score reaches 40 seconds, your average breathing rate would typically be between 8 to 10 breaths per minute. Keep at it and you’ll see improvements!

Understanding the connection between your bolt score and breathlessness during physical activities

When you initially calculate your BOLT score, you might be taken aback to see it’s lower than what you had anticipated. However, don’t let that discourage you. You’d be surprised to know that even high-performing athletes can start off with a low BOLT score! The good news is, your BOLT score can be enhanced quite effortlessly with a set of straightforward breathing exercises that can easily be integrated into your current lifestyle or workout routine.

What does your BOLT score mean?

BOLT below 10: If your BOLT score is less than 10, you might notice your everyday breathing is heavy, uneven, and requires effort. You might be sighing or yawning excessively, and your sleep could be disturbed, causing tiredness. Don’t worry, by performing exercises for breathlessness, you can drastically boost your health and performance.

Between 10-20: If your score is within this range, your breathing might be disrupted due to a stuffy nose, wheezing, or coughing. You might be experiencing interrupted sleep and have low energy and focus. By engaging in breathing exercises designed to elevate your BOLT score, you can improve your sleep quality, decrease breathlessness, and enhance your overall health and fitness.

Between 20-30: With a BOLT score in this range, your usual breathing is likely quiet, relaxed, and easy. Having a score of around 20 seconds is considered good, but there’s always room for improvement for better health and fitness.

If you’re someone who participates in moderate-intensity exercise regularly, a starting BOLT score of around 20 seconds is pretty standard. For every five-second increment in your BOLT score, you’ll notice positive changes like increased energy and reduced breathlessness during physical activities.

With consistent practice of the breathing exercises, you can decrease your CO2 sensitivity. As a result, your BOLT score will gradually increase and you’ll be able to “reset” your brain’s breathing centre, which means less breathlessness during rest and exercise. The ultimate goal of the OA™ program is to boost your BOLT score to 40 seconds, a goal that is achievable with dedication.

Improving your BOLT score is also a crucial step towards achieving better physical endurance. As your body’s tolerance to carbon dioxide improves, you can increase your VO2 max, which ultimately leads to enhanced performance. The Oxygen Advantage® program is all about improving your BOLT score and helping you reach your maximum potential!


How does the body oxygen level test (bolt) work?

Research has demonstrated that your breath-hold duration can be an indicator of your body’s sensitivity to carbon dioxide (CO2). As you hold your breath, the intake of oxygen into your lungs is temporarily paused. Simultaneously, the excess carbon dioxide is held back from being released into the air. As your breath-hold extends, CO2 starts building up in your lungs and blood, and oxygen levels slightly dip.

CO2 is the primary trigger that signals your body to breathe. As CO2 levels rise in your lungs and blood, your brain responds by initiating the breathing process. This implies that your comfortable breath-hold duration is dependent on how much CO2 your body can bear – this is referred to as your “ventilatory response” to CO2.

If your body’s response to CO2 is strong, you’ll hit your tolerance threshold quicker, resulting in a shorter breath-hold time. On the other hand, if you have a higher CO2 tolerance and a lower ventilatory response, you’ll be able to hold your breath for longer. A low BOLT score simply signifies that your breathing receptors are particularly sensitive to CO2. As a result, your breathing volume will be larger as your lungs work to expel the extra CO2, creating a kind of loop where you’re constantly breathing in more air than needed while still feeling perpetually breathless.

But, don’t worry! By practicing the breathing exercises in the OA™ program, you can normalise your CO2 tolerance. Once your CO2 tolerance reaches a normal level, your BOLT score will improve. This will allow you to maintain calm breathing at rest, and more controlled, lighter breathing during physical activity.

The link between your bolt score and asthma symptoms

The utilisation of breath-hold measurements has been pivotal in researching the onset and persistence of breathlessness (also known as dyspnea) and symptoms of asthma. A recurring finding is that a shorter breath-hold duration often corresponds to a higher likelihood of experiencing symptoms like breathlessness, coughing, and wheezing, both during periods of rest and physical activities.

How to improve your bolt score

Work with an Oxygen Advantage instructor like me and learn simple exercises to help you improve your BOLT score. Breathwork coaching can help you improve your functional breathing.

Try this to boost your BOLT score up to 20 seconds. Concentrate on nasal breathing. This applies to when you’re resting and while partaking in light physical activities. Another strategy is to practice seated breathing exercises where you deliberately inhale less air than your body demands. Ensure that your inhalations are brief and gentle, while keeping your exhalations relaxed and effortless.

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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