Mind-Body Relationships in Elite Apnea Divers During Breath Holding, A Study of Autonomic Responses to Acute Hypoxemia
Authors: Marco Laurino, Danilo Menicucci, Francesca Mastorci, Paolo Allegrini, Andrea Piarulli, Enzo P. Scilingo, Remo Bedini, Alessandro Pingitore, Mirko Passera, Antonio L’Abbate, Angelo Gemignani
DOI / Source: https://doi.org/10.3389/fneng.2012.00004
Date: 21 March 2012
Reading level: Intermediate
Why This Matters for Freedivers
This paper gives a rare peek into what “mental control” might look like in the body during apnea. It suggests that trained divers can keep the heart’s control systems unusually steady early in the breath-hold, while emotional arousal shows up more clearly through skin conductance. If you coach or train, it’s a reminder that performance isn’t just lungs and CO₂ tolerance—your nervous system strategy matters, and it may change across different phases of a single breath-hold.
Synopsis
Freedivers often describe breath-holding as a mind–body skill: you’re managing sensations, emotions, and physiology at the same time. This study tried to measure that more directly by looking at two “windows” into the autonomic nervous system during a long, dry breath-hold in elite apnea divers:
- Heart-rate variability (HRV) from ECG, which reflects how the heart is being regulated moment-to-moment.
- Skin conductance (SC), which reflects sympathetic “arousal” to sweat glands and is strongly tied to emotional activation.
Fourteen elite male apnea divers were tested in a quiet room with eyes closed. First they recorded 5 minutes of relaxed normal breathing. Then each diver did a prolonged breath-hold (no hyperventilation beforehand) at sub-maximal inspiration. The clever part is that the breath-hold was split into two phases based on oxygen saturation behavior: - a normoxic phase, where oxygen stayed fairly stable, - and a hypoxic phase, where oxygen started dropping fast and the urge-to-breathe ramps up.
Instead of focusing on just “heart rate went down” (which doesn’t always happen in dry apnea), they looked at patterns in HRV and SC—including frequency measures and more advanced “complexity” style metrics. Then they used a statistical technique (factor analysis) to see whether these different measures cluster into a few underlying control systems.
What they found (in simple terms)
- Heart rate itself didn’t change much across phases. That can sound surprising until you remember this was dry apnea with no cold face immersion, and breathing stopping alone can change HRV patterns even when average heart rate stays similar.
- During the early (normoxic) phase, the “breathing-related” HRV components dropped sharply—basically because normal breathing rhythms that modulate the heart were suspended.
- As the breath-hold progressed into the hypoxic phase, involuntary breathing movements tend to reappear and become more regular. Many HRV features shifted again, consistent with that return of rhythmic respiratory drive and increasing strain.
- Skin conductance activity increased, especially later, suggesting that the emotional/drive component of the breath-hold (air hunger, internal stress) shows up clearly in the skin’s sympathetic pathway.
The most interesting idea
Their factor analysis suggested that, in trained divers, the early breath-hold phase may involve a kind of “decoupling” where the heart’s regulation looks less driven by the usual central/autonomic patterns, while skin conductance becomes a clearer readout of the central emotional drive. In plain language: elite divers may keep the heart-control side relatively “quiet” early on (useful for performance), while the emotional arousal signal shows up elsewhere—and then hypoxia changes the picture again.
This doesn’t mean divers can “control hypoxia,” but it supports a more realistic training view: the breath-hold is not one single state. It evolves. Early on, you can ride relaxation and control; later, physiology and survival signals take over, and your job becomes managing the response without making it worse.
Abstract
Voluntary breath-holding is a psychophysiological condition in which mental control of ventilation is accompanied by cardiovascular and emotional-autonomic changes, especially as oxygen levels fall. This study recorded ECG-derived heart rate variability and skin conductance in 14 elite apnea divers during free breathing and during a prolonged dry breath-hold. The breath-hold was divided into a normoxic phase and a hypoxic phase based on the oxygen saturation time course. Multiple HRV metrics (time, frequency, and nonlinear measures) and skin conductance response features were compared across conditions. Factor analysis identified latent components describing autonomic balance, information/complexity-related dynamics, and central nervous system drive, and suggested that autonomic control of the heart and skin are modulated differently across breath-hold phases. The findings support the idea that trained divers show distinct autonomic patterns during breath-holding that may relate to learned emotional control and phase-specific physiology.