Claim Check: "Breath-Hold Tests Measure Your Health"

The claim

Some breathing programs and apps say a timed breath-hold, often called the BOLT score, shows how well your body tolerates carbon dioxide (CO2) and how fit or healthy you are. A research paper describes the claim this way: according to its proponents, the score reflects the body's sensitivity to carbon dioxide. [4] The same score is also known as the "control pause" in the Buteyko method. [5]

The short answer

Mixed to insufficient evidence. A timed breath-hold can mean something in a hospital or research setting, in specific patient groups, with trained staff. We found no good evidence that a home breath-hold score measures your general health, fitness or "CO2 tolerance" in a way you can act on.

What studies found

1. Does breath-hold time track CO2 sensitivity?

   Promising in one patient group; small

   In 43 people with chronic heart failure, breath-hold time was inversely related to a separate CO2 test, and the authors called the breath-hold a reliable and safe method in that group. [6]

2. Is it the same in healthy people?

   Mixed

   In healthy men with and without obesity, CO2 sensitivity did not differ between groups, yet breath-hold time was lower with a higher BMI. [7]

3. Does BOLT predict fitness?

   No good evidence of benefit as a fitness measure

   In 49 elite speedskaters, no significant correlation with performance tests. [4] In 28 active students, BOLT was not significantly associated with aerobic capacity or exercise levels, and the authors urged caution if it is used for fitness. [5]

4. Can it screen for lung disease?

   Promising but limited

   In 293 adults, breath-hold times were lower in those with abnormal spirometry. At one cut-off, sensitivity was 90.43% and specificity 55.06% for identifying normal spirometry. The authors suggest a rule-out step before spirometry, pending external validation. [8]

5. Can it flag risk in COVID-19?

   Insufficient evidence; hospital use only

   In 50 hospital patients, breath-hold measures were linked to worse outcomes. [9] In a later 110-patient study, the positive predictive value was 9/48. [10]

Why one number can mislead

Breath-hold time is not a fixed trait. In 78 young adults it fell during a handgrip task and rose during other tasks. [11] So a single reading is hard to interpret. Spirometry, a standard lung test, measures how much air you breathe out and how fast, and doctors use pulmonary function tests to help diagnose conditions such as asthma and emphysema. [12]

Practice and "improving your score"

Proper evidence not found that raising your breath-hold time improves health. We searched PubMed for BOLT, breath-hold test, CO2 tolerance and breath-hold training, and found no trial testing that. In one small Buteyko asthma trial (60 people) the control pause was the primary outcome. [13] A number that changes is not proof that the number itself matters for health.

Hyperventilation is considered a major risk factor for hypoxic blackout during breath-hold diving, because it delays the point at which a person has to breathe. [14] Do not do this. Details of the method are on the Buteyko page.