Voluntary apnea in diver - from the genesis to consequences

Abstract

Introduction: Voluntary apnea under water is becoming increasingly popular not only among athletes but also fitness enthusiasts eager to test their physical and psychological limits. Furthermore, voluntary apnea bears some similarities and differences with involuntary sleep apnea, which is highly instructive from a scientific point of view. Methods: We discuss breath-hold dive from a strategic perspective, starting with the surface time, followed by descent, bottom time, and ascent, and then finishing with the resting on the surface. The ambient and body challenges are discussed, along with the triggered physiological body actions and expected consequences. Results: The voluntary apnea is an intrinsically instable state triggering multiple physiological and psychological reflex actions of the human body, with the explicit aim to compensate for ceased breathing and/or to resume breathing. The external challenges the human faces include absent air, ambient pressure, and cold. Different phenomena and their consequences are discussed in depth, such as lung packing, blood centralization, Valsalva, diving reflex, nitrogen narcosis, arrhythmia, and others. Conclusions: The human excellence under water and in apnea shows not only autonomic regulatory fitness of the diver but also demonstrates pathophysiological boundaries. The reflex pathophysiology of the human body in apnea diving offers instructive insights into the pathophysiology of sleep apnea, the involuntary counterpart of voluntary apnea.