The Body Oxygen Level Test (BOLT)

Measure BOLT

As far back as 1975, researchers noted that the length of time of a comfortable breath hold served as a simple test to determine relative breathing volume during rest and breathlessness during physical exercise (1,2).

The Body Oxygen Level Test (BOLT) is a very useful and accurate tool for determining this relative breathing volume.

The ideal BOLT score for a healthy individual is 40 seconds. In the book entitled 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).”

In short, the lower the BOLT score, the greater the breathing volume, and the greater your breathing volume, the more breathlessness you will experience during exercise.

Measure your BOLT Score now
To obtain 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 on hand. You can measure your BOLT now:

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. 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 the body gives the message to resume breathing. (Note that 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.)

4. Release your nose, stop the timer, and breathe in through your nose. Your inhalation at the end of the breath hold should be calm.

5. Resume normal breathing.

How the Body Oxygen Level Test (BOLT) Works

When you hold your breath, you prevent oxygen from entering your lungs and prevent excess carbon dioxide from being expelled into the atmosphere. As the breath hold continues, carbon dioxide accumulates in the lungs and blood while oxygen levels slightly decrease. Since carbon dioxide is the primary stimulus for breathing, the length of your breath hold time is influenced by how much carbon dioxide you are able to tolerate, or your ventilatory response to carbon dioxide.(1)

A strong ventilatory response to carbon dioxide means that your threshold will be reached sooner, resulting in a lower breath hold time. Conversely, a good tolerance and reduced ventilatory response to carbon dioxide results in a higher breath hold time.

When your BOLT score is lower, your breathing receptors are especially sensitive to carbon dioxide and your breathing volume will be greater as the lungs work to remove any carbon dioxide in excess of programmed levels. However, when you have a normal tolerance to carbon dioxide and a higher BOLT score, you will be able to maintain calm breathing during rest and lighter breathing during physical exercise.

You may find that the first time you measure your BOLT, you are surprised that your score is lower than expected, but remember that even elite athletes can have a low BOLT score! The good news is that your BOLT score can easily be increased with a series of simple breathing exercises incorporated into your existing way of life or exercise regime.

A common starting BOLT score for an individual who exercises regularly at a moderate intensity will be approximately 20 seconds. If your BOLT score is below 20 seconds, depending on genetic predisposition, you will probably find you experience a blocked nose, cough, wheeze, disrupted sleep, snoring, fatigue and excessive breathlessness during physical exercise. Each time that your BOLT score increases by five seconds, you will feel better, with more energy and reduced breathlessness during physical exercise.

The aim of the Oxygen Advantage® 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. As we have already seen, having an improved tolerance to carbon dioxide means you are able to achieve a higher VO2 max and improved performance. The Oxygen Advantage® program is all about increasing your BOLT score and maximising your potential!

How Your BOLT Score Relates to Breathlessness During Sports

The truth is that the vast majority of individuals, including elite athletes, have a comfortable breath hold time of about 20 seconds, often less. However, to achieve your full potential, a BOLT score of 40 seconds should be the goal.

Breath hold measurements have also 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 both rest and exercise.