When you take a breath, oxygen is drawn in to your lungs and carbon dioxide is exhaled. Normally, it is a completely automatic process occurring thousands of times a day. However, when you hold your breath, carbon dioxide begins to build up with nowhere to go. At a certain point, the carbon dioxide crosses the blood-brain barrier and your brain becomes aware that you’re no longer getting fresh oxygen. This triggers a drive to breathe and you may feel lightheaded, weak or dizzy. If you continue to hold your breath, the body will start to use up all the oxygen in its system and can cause a seizure or even pass out. This is referred to as hypoxia.
The average person can only hold their breath for about 30 to 90 seconds without training. Professional free divers spend years preparing for their breath holds, but even they would admit that it’s an incredibly difficult feat.
The longest-held breath was 11 minutes 54 seconds by Branko Petrovic of Serbia. He achieved this in a static apnea competition, which doesn’t allow the use of oxygen in preparation for the dive. The Guinness World Record for longest breath hold underwater is 24 minutes 3 seconds, held by Aleix Segura Vendrell of Spain. He used what is called an oxygen-assist. This involves breathing pure oxygen for a set period of time prior to the dive. You can read more about his record-breaking feat here.
