Guide

CO₂ and O₂ tables: how to use them

Two tools, two different goals — and one very common mistake.

Tables are the foundation of dry freediving training. But many practitioners do them backwards, or mix them up. Here's what each one actually does.

The CO₂ table: tolerating the urge to breathe

Principle: the breath-holds always keep the same duration, but the recoveries between them get shorter each round.

The result: carbon dioxide never has time to be fully cleared. It builds up from one round to the next, and your body learns to function with that discomfort.

What it develops: bottom time and the ability to chain dives. For a spearo, it's the most rewarding quality.

Example (baseline 2 min 30 → hold ≈ 1 min 23):

The O₂ table: raising the ceiling

Principle: exactly the opposite. The recoveries stay long and constant, and it's the breath-holds that get longer progressively until they approach your maximum.

Since you start "fresh" each time, the difficulty doesn't come from accumulated CO₂ but from the duration itself: you're training tolerance to the lack of oxygen.

What it develops: maximum duration, and therefore a margin on deep dives.

Example (baseline 2 min 30, fixed recovery ≈ 2 min 15):

Calculating your times

Everything starts from a maximal dry static breath-hold, measured calmly, lying down. Let's call it Max. Then:

• CO₂ table: constant hold ≈ 55% of Max, recoveries starting around 1 min 45 and dropping toward 45 s.
• O₂ table: breath-holds from 45% to 78% of Max, fixed recovery ≈ 90% of Max.

How to progress (without breaking everything)

The right way to make a table harder depends on the table:

• CO₂ table → you shorten the recoveries (and possibly add a round). You don't touch the duration of the breath-holds.
• O₂ table → you lengthen the breath-holds. You don't touch the recoveries, which must stay complete.

And you only progress once the current session has become comfortable — typically after three or four sessions that felt easy. Between two levels, the load stays stable: that's how you build a solid adaptation rather than chronic fatigue.

The classic mistake

Breathing deeply between the rounds of a CO₂ table. It's instinctive — the discomfort rises, you want to clear it. But by clearing all the CO₂, you remove exactly the stimulus the session is trying to create. The table becomes useless.

The rule: between rounds, normal, calm breathing, neither rushed nor deep. And never hyperventilate before a breath-hold: it masks the natural alarm and seriously increases the risk of blackout.