Breath-hold Diving Strategies to Avoid Loss of Consciousness, Speed Is the Key Factor
Authors: Clément Poiret, Marion Noulhiane, Eric Clua, Frédéric Lemaître
DOI / Source: https://doi.org/10.1080/14763141.2020.1820073
Date: 03 December 2020
Reading level: Intermediate
Why This Matters for Freedivers
This paper is a rare one because it looks at what actually happens in real competitions, not just lab physiology. The takeaway is blunt and useful: blackout risk isn’t only about “oxygen” — it’s also about how you move, especially how fast you choose to go at different phases. That makes it directly actionable for training, coaching, and even self-checking your pacing strategy.
Synopsis
Freedivers often talk about blackout like it’s purely a physiology problem: “I stayed too long,” “my O₂ dropped,” “CO₂ got me.” This study adds a different angle: your dive strategy and movement pattern can shift blackout risk, even among high-level athletes.
The researchers analysed competition videos from three international events (2018), focusing on two depth disciplines: - CNF (constant weight, no fins), and - CWT (constant weight with fins).
Instead of guessing what divers intended to do, they broke each dive into clear phases and measured what the diver actually did: 1) Active descent (when you’re still moving yourself down), 2) Passive descent (gliding/sinking), 3) Turn (tag + direction change), 4) Ascent.
For each phase they calculated time, speed, and movement count, then derived frequency (moves per second) and amplitude (how much distance you get per move, basically “efficiency”).
What they found in CNF (no fins)
Divers who had a loss of consciousness tended to show an “inefficient pattern”: - They were slower during active descent (working longer for the same progress), - Then faster during passive descent (likely compensating or affected by buoyancy/timing), - Had a longer turn, and - Were slower on ascent than divers who finished cleanly.
They also showed lower amplitude and higher frequency — a classic sign of doing more work for less progress (more “churning,” less glide), which can increase oxygen cost.
What they found in CWT (with fins)
The pattern was different: - Divers with LOC had longer total dive times, - And a noticeably faster active descent than successful divers.
Here the authors’ interpretation is practical: going down too fast early may raise overall effort and oxygen use, or reflect stress-driven pacing choices, which then pushes the diver closer to the edge later in the dive.
The big coaching takeaway
The paper basically suggests there are “safer speed windows” depending on the discipline: - In CNF, being too slow during active descent (and later on ascent) is linked with LOC risk — likely because it stretches dive time and increases movement cost. - In CWT, being too fast during the active descent is linked with LOC risk — likely because it increases early effort and may create a longer, harder overall dive.
The authors also point out limitations: they didn’t have data on buoyancy details (wetsuit thickness, ballast, exact lung volume/packing), and they didn’t measure physiology directly. But even with those limits, this is valuable because it shows that blackout risk has a technique/pacing signature, not just a physiological one.
Abstract
This study examined whether breath-hold diving strategies are associated with loss of consciousness in deep competition dives. Videos from three international competitions were analysed in constant weight diving with fins (CWT) and without fins (CNF). Dives were divided into active descent, passive descent, turn, and ascent, and phase-specific measures of time, speed, and movement count were used to derive frequency and amplitude. In CNF, divers with loss of consciousness were slower during active descent, faster during passive descent with a longer turn, and slower during ascent compared with divers who completed valid performances, and they showed lower amplitude and higher frequency. In CWT, loss-of-consciousness dives had longer total dive times and a faster active descent phase. The findings suggest that speed and movement efficiency—especially during active descent—are key strategy variables linked to loss of consciousness risk in competitive breath-hold diving.