There are a lot of freedive myths out there, and the internet is especially rife with misinformation. Here, we debunk the most common misconceptions,  all corroborated by the most up-to-date scientific research.

Freediving causes brain damagefalseA scientific review concluded there was no evidence of brain damage resulting from competitive freediving. In fact, the opposite appears to be true: other studies have shown that cognitive function improves after extended apnea. The dive response means that even when your body is in a hypoxic state overall, your brain remains well oxygenated, and will be right up until the very end of a breath-hold (divers should be stopping your dive before this stage anyway!).
Competition freediving has had many fatalitiesfalseIn over 100,000 competition dives and millions of training dives, nobody has ever died from hypoxic blackout when basic safety protocols have been followed. Most deaths which are called “freediving” deaths are spearfishermen who dive alone. There have also been high-profile sled (no limits) accidents, resulting from mechanical failures and the extreme depths, which are far greater than those in competition freediving. AIDA suspended ratification of the No Limits discipline in 2012 due to risk concerns. In competitive freediving disciplines, there has been only one fatality (Bahamas, 2013). It was in a depth discipline, and was not due to a hypoxic blackout. Sports such cycling, running and scuba diving actually have a higher fatality rate than competitive freediving.
Breath hold is all about your lung capacityfalseMost of your oxygen (>50%) is stored in your blood, in haemoglobin. 13% is stored in muscle in myoglobin, and up to just ~35% in the lungs. Breath hold is about how well you conserve the oxygen you have, and this comes down to the dive response. Big lungs can help, especially at the elite level… but they’re not the most important thing.
People in their physical prime (20s-30s) have the best breath holdfalseThere are too many world champions and record holders past their 50s for this to be true: and they are still improving! The reasons aren’t yet confirmed, but it is hypothesised that long-term training effects more than compensate for any decreases in physical performance, and that the slowing metabolic rate that comes with age is actually an advantage.
All hypoxia, and thus freediving, is bad for youfalseIn fact, the opposite is true! There are many benefits associated with controlled hypoxia, as seen in altitude training. The body becomes better able to use the oxygen it has and is more tolerant to hypoxic states, as well as having a natural increase in EPO leading to higher production of red blood cells. As an added bonus, freediving also improves cardiovascular and pulmonary efficiency, as well as elasticity of the chest and diaphragm, increasing your lung capacity.
A blackout means you have run out of oxygenfalseA blackout is actually another oxygen conservation adaptation, essentially a form of forced hibernation. Humans have this mechanism to slow the rate of oxygen consumption in the brain (it accounts for over 20% of the body’s oxygen use) and increase survival time in a low-oxygen environment. There is generally another 3-4 minutes of oxygen remaining following a blackout before the body’s vital processes are under threat, which is why it is so important that active safety is always there to bring a diver to the surface immediately.