Let's move on to physiology. The human body has an amazing ability to adapt to being underwater. One of the key aspects is the mammalian diving reflex, or "diver's reflex". This is an instinctive reaction to immersion that involves a reduction in heart rate (bradycardia), constriction of blood vessels (vasoconstriction) to conserve blood in vital organs, and an increase in blood pressure. This reflex helps conserve oxygen and protects the body from potential underwater hazards.
There are air spaces in the ears, and to prevent painful pressure on the eardrums, freedivers use pressure equalization techniques. One of the most preferred methods for freediving is the "Frenzel method". Unlike the Valsalva maneuver, the Frenzel method does not require active use of abdominal muscles, allowing the freediver to remain more relaxed during the dive. This pressure compensation technique is thoroughly studied in the
courses at our freediving school.