ApneaCO2 Tables for Freediving: What They Are and How to Train With Them
A CO2 table is a structured breath hold workout: a series of holds at a fixed length, usually around half of your maximum, separated by rest periods that get shorter with every round. Because the rests shrink, carbon dioxide builds up in your blood hold after hold. That is the point. CO2 tables train you to stay relaxed through the very signal that makes most people give up.
Why CO2 tolerance is the key to longer holds
The urge to breathe is triggered by rising CO2, not by low oxygen. An untrained person surfaces, or breaks a hold, with most of their oxygen unused, simply because the CO2 alarm feels unbearable. Raise your tolerance to that alarm and your existing lungs instantly buy you more time. This is why CO2 tables produce such fast early progress: reviewers of the Apnea app report doubling their hold within days of starting table training.
A worked example: CO2 table for a 2:00 max
The classic format is eight rounds. Holds are fixed at roughly 50 percent of max; rests start comfortable and lose 15 seconds each round.
| Round | Breathe (rest) | Hold |
|---|---|---|
| 1 | 2:00 | 1:00 |
| 2 | 1:45 | 1:00 |
| 3 | 1:30 | 1:00 |
| 4 | 1:15 | 1:00 |
| 5 | 1:00 | 1:00 |
| 6 | 0:45 | 1:00 |
| 7 | 0:30 | 1:00 |
| 8 | 0:15 | 1:00 |
By round six the rests no longer clear the CO2 from the previous hold, and the real training begins. The last three rounds should be uncomfortable but controlled. If you are failing holds, the table is too hard; if round eight feels easy, it is too easy. Both mean the table should be rebuilt from your current max.
In the Apnea app
This is exactly what Apnea automates. Enter your max once (or take the guided test) and the app calculates the whole table for you, counts down every rest, and talks you through every hold with customisable audio coaching, so you never open your eyes to check a stopwatch. Finished sessions land in your training history, and when your max improves, your next table scales up automatically. There is a native Apple Watch app too, so you can run a table from your wrist.
How often should you train CO2 tables?
Two to three CO2 sessions per week is the sweet spot, on non-consecutive days, with at most one table per day. Adaptation happens between sessions. Pair them with one weekly O2 table once the CO2 work starts feeling manageable, and retest your max every one to two weeks so the tables keep pace with you.
Common CO2 table mistakes
- Hyperventilating during the rests. Big fast breaths defeat the purpose of the table and are dangerous. Breathe slowly and calmly, even when the rests get short.
- Doing tables in water alone. Tables are dry training. In water, a buddy is non-negotiable.
- Chasing pain every day. Daily maximal discomfort leads to burnout and stalled progress, not faster gains.
- Never updating the table. A table built on an old max stops training you. Retest and rebuild.
Safety first
Do all table training dry: sitting or lying down on land. Never practice breath holds in water without a trained buddy watching you, never hyperventilate before a hold, and never do breath holds while driving. If you have a heart or lung condition, or you are pregnant, talk to a doctor before training. Blackouts can happen without warning, even to experienced divers.
Stop building spreadsheets. Start holding.
Apnea generates a personalised CO2 table from your max breath hold and coaches you through every hold and rest with audio cues. Eyes closed, fully guided.
Free to download. 4.8 stars, 2,894 App Store ratings.