O2 Table (Apnea)

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Breathe In

Cycle 1 of 4

30 seconds per cycle

1 minute 30 seconds total

inhale

hold

20s

exhale

A breath-hold endurance drill from freediving that extends the hold after a full inhale to train the body to work with less oxygen.

Cadence: 2 bpm
Difficulty: advanced
Family: Train
For: Performance

How to practice

1.Sit or lie down on dry land. Never in or near water, never standing, never while driving.
2.Take a few relaxed breaths, then draw a full but unforced inhale, around 80–90%, not a strained cram.
3.Hold with a relaxed throat and body, staying calm and still as the urge to breathe builds.
4.Release at your planned time (well before any real distress) and recover with full, calm breaths.
5.Keep the recovery interval the same each round and extend the hold time only gradually across the table.
6.End the session at once if you feel faint, see spots, tingle strongly, or your vision starts to narrow.

When to use this

As dedicated, seated dry-land apnea training for freedivers and spearos who want to extend comfortable hold time and tolerance to low oxygen. Not a calming tool, and not a daily practice.

Benefits

Extends comfortable breath-hold time
Improves oxygen efficiency
Builds mental calm under stress
Supports endurance sport

Mechanism

A full-inhale hold loads the lungs with oxygen; as the hold continues, oxygen saturation gradually falls (mild hypoxia) while CO2 rises. An O2 table keeps the recovery interval constant and lengthens the holds, taking you progressively deeper into low-oxygen territory to train tolerance and trigger the mammalian dive response, a slowed heart rate, narrowing of peripheral blood vessels, and spleen contraction that releases extra oxygen-carrying red cells. As CO2 and acidity rise, haemoglobin also releases its oxygen to the tissues more readily (the Bohr effect). Because you are genuinely lowering your oxygen, O2 tables carry more risk than CO2 tables and demand more caution.

Evidence

Apnea physiology is well documented: the dive response, spleen contraction, and elevated red-cell counts in trained divers are real and measurable. Transfer of breath-hold training to non-diving sports is more mixed and less proven. This is genuine hypoxic stress, so treat O2 tables as a specialised freediving drill with hard safety limits. Not a general fitness or health practice.

Lineage

O2 tables sit alongside CO2 tables as the two staple 'dry' training tools of competitive freediving, formalised within apnea coaching and organisations such as AIDA. They grew out of the static-apnea discipline, where divers train to hold a single breath as long as safely possible.

Variations and progression

Classic structure: hold the recovery interval constant and lengthen each hold across the table (the mirror image of a CO2 table).
Shorter, more conservative tables for those newer to breath-holds; longer tables only with a coach.
Run tables with a partner or coach watching, since the low-oxygen end is where blackouts happen.

Master CO2 tables first (they carry less blackout risk) and build a calm, controlled baseline hold. Increase hold times in small increments over weeks, logging each session, and only when the table stays relaxed throughout. Never take breath-holds into the water without a trained buddy and a qualified instructor.

Practice next

Common mistakes

Jumping to O2 tables before CO2 tables. O2 tables push oxygen lower and sit closer to blackout.
Hyperventilating before the hold to extend it, which masks the warning signs and raises blackout risk.
Chasing maximum holds or personal bests every single session instead of building slowly.
Practising near water or completely alone, where a blackout would be dangerous.

FAQ

What's the difference between an O2 table and a CO2 table?

A CO2 table keeps the hold length fixed and shortens the rests to build tolerance to air hunger; an O2 table keeps the rests fixed and lengthens the holds to build tolerance to low oxygen. O2 tables are more demanding and sit closer to blackout, so approach them more cautiously.

Is this dangerous?

On dry land, seated, with conservative times and no hyperventilation, most healthy people tolerate it, but the oxygen drop is real, which is exactly why the water and health rules below are absolute.

How do I know I'm pushing too far?

Stop well before distress. A blackout can arrive with little warning; dizziness, tingling, tunnel vision, or confusion mean stop immediately.

Safety

NEVER practice breath-holds in or near water (even shallow water) because a shallow-water blackout leads to silent drowning. Never train breath-holds while driving.
Always train seated or lying down on dry land, somewhere you could safely rest if you did black out.
Skip this entirely if you are pregnant, or if you have cardiovascular or heart disease, high blood pressure, epilepsy, or any history of fainting or blackouts.
Never hyperventilate to extend a hold; stop the moment you feel faint, tingle strongly, see spots, or feel chest pain or a pounding heart.
Learn from a qualified freediving instructor and always use a trained buddy before doing any breath-holds in water.

Breathwork is a complement to (not a replacement for) professional medical care. If you have a heart, respiratory, or blood-pressure condition, are pregnant, or feel unwell, check with a clinician before practising breath-hold techniques.