The question of how long a person can hold their breath, known as apnea, taps into the limits of human physiology and endurance. For most people, voluntarily stopping breathing lasts only a short time before a powerful, involuntary urge forces a breath. Highly trained athletes, known as freedivers, have developed techniques to extend this limit far beyond what is considered normal. The longest possible breath-hold involves distinguishing between the unaided human capacity and the specialized protocols used in competitive settings.
The World Record and Context
The absolute longest time a person has held their breath is 29 minutes and 3 seconds, a Guinness World Record achieved by Croatian freediver Vitomir Maričić. This time was accomplished in the category of voluntary static apnea using a pre-breath of pure oxygen. This technique saturates the bloodstream with oxygen, maximizing the body’s initial reserves and allowing for a vastly extended duration.
For a more accurate measure of the unaided human limit, the category of static apnea without pure oxygen pre-breathing is used. The AIDA men’s world record for static apnea on air is 11 minutes and 35 seconds, set by Stéphane Mifsud. Static apnea is defined as holding one’s breath while remaining stationary, usually face-down in water. This is distinct from dynamic apnea, which involves swimming a distance while holding the breath.
The Body’s Urge to Breathe
For an untrained individual, the limit on breath-holding is determined not by a lack of oxygen, but by the accumulation of carbon dioxide (CO2). As cells produce energy, CO2 is generated as a waste product that dissolves in the blood. Rising CO2 levels make the blood more acidic, a change immediately detected by specialized sensory cells called chemoreceptors in the brainstem and arteries.
This detection of elevated CO2, known as hypercapnia, triggers the powerful, involuntary urge to breathe. This signal is the body’s alarm system, designed to regulate blood acidity and expel the waste gas before oxygen levels become dangerously low. This involuntary reflex typically forces a breath after 30 to 90 seconds, long before oxygen depletion becomes a significant issue.
Because the brain’s primary breathing drive is sensitive to CO2, this protective mechanism can be circumvented. If a person hyperventilates—breathing rapidly and deeply—before holding their breath, they flush out significant amounts of CO2. This artificially lowers the starting level of CO2, delaying the point at which the chemoreceptors trigger the urge to breathe.
Maximizing Time Underwater
Elite freedivers extend their breath-hold times by consciously overriding the CO2-driven urge to breathe and by optimizing the Mammalian Dive Reflex (MDR). The MDR is an involuntary survival mechanism, most pronounced when the face is submerged in cold water, though breath-holding alone can partially activate it.
The reflex involves responses aimed at conserving oxygen for the heart and brain. A primary effect is bradycardia, a significant slowing of the heart rate, which reduces the body’s overall oxygen consumption. Heart rates can drop by 10 to 25 percent during a dive, sometimes more in highly trained individuals.
The MDR also triggers peripheral vasoconstriction, causing blood vessels in the limbs and non-essential muscle groups to constrict. This action shunts oxygenated blood toward the body’s core, prioritizing the brain and heart. Additionally, some divers experience splenic contraction, where the spleen releases a reserve of oxygen-rich red blood cells into the circulation, boosting the blood’s oxygen carrying capacity.
Divers train for years to manage the intense diaphragm spasms, known as contractions, which are the physical manifestation of the CO2 alarm. They employ mental focus and relaxation techniques to suppress the panic and discomfort associated with these contractions. The initial pure oxygen pre-breath, used in the record category, maximizes oxygen stores, allowing the diver to sustain metabolism for an extended time before oxygen saturation drops.
The Risks of Pushing the Limit
The techniques used to extend breath-hold time carry severe risks, especially when manipulating the body’s natural CO2 alarm. The most significant danger is hypoxia, a state of dangerously low oxygen levels that primarily affects the brain. Prolonged hypoxia can cause immediate loss of consciousness, seizures, and permanent neurological damage.
A specific and often fatal consequence is Shallow Water Blackout (SWB), which is a loss of consciousness due to cerebral hypoxia while underwater. This often occurs after an individual hyperventilates to delay the urge to breathe, leading to a critical drop in oxygen without the usual warning signs. The blackout can happen during the dive or, more commonly, during the ascent phase.
As a diver rises toward the surface, decreasing water pressure causes the partial pressure of oxygen in the lungs to drop rapidly. This phenomenon can quickly push blood oxygen saturation below the threshold needed to maintain consciousness. When unconsciousness occurs underwater, the body’s natural reflex to breathe returns, causing the person to inhale water and drown. For this reason, official freediving attempts are always conducted under the strict supervision of trained safety divers.