Humans are air-breathing mammals, which naturally limits how long they can remain submerged without external oxygen. Unlike aquatic animals, humans rely on air stored in their lungs and oxygen dissolved in their blood and tissues. This article explores the physiological responses, capabilities, and risks associated with staying submerged without an external breathing apparatus.
Typical and Record Breath-Holding Times
The average person can comfortably hold their breath underwater for 30 to 90 seconds, a duration that fluctuates based on physical fitness and training; however, for individuals who undergo specialized training, known as free divers, these times can extend significantly. Professional free divers achieve remarkable feats through dedicated practice. The male world record for static apnea, where a person holds their breath while stationary underwater, stands at 11 minutes and 35 seconds. The female world record for static apnea is 9 minutes and 22 seconds. Some exceptional records, like one reaching 24 minutes and 37 seconds, involve pre-breathing pure oxygen, which is a specific technique not typically used in standard free diving.
The Body’s Underwater Adaptations
When a person holds their breath, the body consumes stored oxygen and produces carbon dioxide; the accumulation of carbon dioxide, not lack of oxygen, is the primary trigger for the uncomfortable urge to breathe, signaling the brain to inhale. The human body possesses the mammalian dive reflex, activated when the face is submerged in cold water. This reflex causes the heart rate to slow down (bradycardia) and narrows blood vessels in the limbs (peripheral vasoconstriction) to redirect oxygen-rich blood towards vital organs like the heart and brain. For deeper dives, a “blood shift” can also occur, where blood moves into the thoracic cavity and lungs to prevent collapse from pressure. While the mammalian dive reflex helps optimize oxygen use, it cannot indefinitely counteract the body’s metabolic demands, and ultimately, limited oxygen reserves and increasing carbon dioxide levels dictate breath-hold duration.
Extending Breath-Holding Duration
Free divers employ various techniques to extend their breath-holding capabilities, often through rigorous training and mental conditioning. One method involves improving lung capacity and efficiency; regular cardiovascular exercise strengthens the respiratory system, and specific breathing exercises like diaphragmatic breathing and lung stretching can increase the volume of air the lungs can hold. Another technique, sometimes used by experienced free divers, is hyperventilation, which involves rapid, deep breaths before a hold; this temporarily reduces carbon dioxide levels in the blood, delaying the urge to breathe, but carries significant risks and is generally discouraged. Mental control and deep relaxation are important for prolonged breath-holding, as a calm mind and body consume less oxygen, allowing for a more efficient use of available stores. Techniques like mindfulness and focused concentration help divers manage the increasing discomfort from carbon dioxide buildup and extend their time underwater, and pre-dive preparation, including slow, deliberate breathing, maximizes oxygen intake and relaxation before a breath-hold attempt.
Dangers of Pushing Limits
Attempting to extend breath-holding beyond safe limits, especially without proper training and supervision, carries substantial risks. One danger is hypoxia, a condition where the body’s tissues and organs, particularly the brain, are deprived of sufficient oxygen; prolonged hypoxia can lead to severe consequences, including irregular heart rhythms, damage to organs like the kidneys and liver, seizures, and even permanent brain injury. Shallow water blackout is a risk, often occurring without warning; this loss of consciousness typically happens near the surface, often exacerbated by hyperventilation before a breath-hold, and can lead to drowning if the individual reflexively inhales water. Other risks include loss of motor control (LMC), where a diver experiences involuntary muscle spasms or an inability to coordinate movements due to low oxygen, which can precede a blackout and compromise a diver’s ability to surface safely. Pressure-related injuries, known as barotrauma, can affect air-filled spaces in the body, such as the ears, sinuses, and lungs, if pressure is not equalized during descent or ascent; because of these serious hazards, breath-holding should never be practiced alone, and any advanced training should always be conducted under the guidance of certified professionals.