Extraordinary breath-holding

How it works

The urge to breathe does not come from lack of oxygen. It comes from rising carbon dioxide, which sensors in the brainstem detect². An untrained adult holds for 30 to 90 seconds before the urge wins¹. The body still has plenty of oxygen at that point.

Freedivers train three things. They learn to tolerate carbon dioxide, so the urge arrives later and hurts less. They enlarge their lungs with stretching and with “packing”, gulping extra air after a full breath². And they use the diving reflex. Cold water on the face slows the heart and shifts blood away from the limbs, which cuts oxygen use⁴. Face down in water, lying still, a trained diver can go past 10 minutes.

The record for static apnea, breath-holding at rest in water, is 11 minutes 35 seconds on ordinary air, set by Stéphane Mifsud in 2009¹. Breathing pure oxygen first loads the blood and lungs with far more oxygen. In that category, Budimir Šobat of Croatia held for 24 minutes 37 seconds in 2021¹. Both were done with safety divers watching. Breath-holding alone in water causes blackouts and drownings every year². Do not try long holds in water.

History and culture

The Bajau of Southeast Asia, often called sea nomads, have dived for food for centuries. They spend hours a day underwater and dive tens of metres on one breath³. A 2018 study found their spleens are about 50% larger than those of a neighbouring farming group³. The spleen stores oxygen-rich red blood cells and squeezes them out during a dive. The size difference is linked to a gene variant, PDE10A, and it is present even in Bajau who do not dive³. It is one of the clearest cases of recent natural selection in humans.