Besides having fun, freediving has many health benefits. Freediving improves lung capacity, reduces inflammation, improves respiratory efficiency, and increases muscle flexibility. It is especially beneficial for those who regularly practice.
One of the most serious medical risks from freediving is neurological damage. The brain uses about 20% of the oxygen supply. When oxygen levels in the blood drop below a certain level, the brain will begin to starve. When the brain cannot maintain consciousness, the person will black out.
Freediving also puts people at risk for heat stroke, hypothermia, and dehydration. Freediving can be dangerous for people who have heart problems.
In order to perform freediving, a person must have a heart rate that is low enough to sustain consciousness. For most people, the average resting heart rate is 60 to 100 beats per minute.
The average freediving heart rate is below half that. The lowest reported heart rates were 14 beats per minute. These low rates cannot support consciousness, but physiologists say it’s a risk that freedivers should take into consideration.
Using MRI, the University of Bonn studied the cardiovascular effects of freediving. They studied 17 German and Austrian freedivers and recorded their electrocardiograms, blood pressure, and oxygen saturation.
They found that the blood flowing to the brain increased after the apnea period, but then returned to normal after the divers breathed. These findings suggest that freedivers may be able to pre-condition the brain to reduce the risk of neurological disorders during surgical procedures. They also suggest that freedivers could help scientists understand the physiology of marine mammals.