Safety First
Never practice static apnea or breath-hold training alone. All in-water breath-hold practice requires a trained buddy watching continuously. Dry training (on land) is the exception - you can practice CO2 tables safely without a buddy.
CO2 Tables — Building Tolerance
CO2 is what triggers the urge to breathe. Your oxygen could still be adequate for several more minutes — but if CO2 has risen enough, the diaphragm contracts and the urge to breathe becomes overwhelming. Most beginner freedivers hit their ceiling because of CO2 discomfort, not actual oxygen depletion.
CO2 tables train your nervous system to stay calm at elevated CO2.
The Format
Fixed hold time → decreasing rest interval. Each round: hold, then rest. The hold time stays the same. The rest interval decreases, so each successive hold starts with more residual CO2.
Example CO2 Table
For a diver with a 2-minute working breath hold — use 50–60% of your maximum.
The table should feel uncomfortable by rounds 5–6, not be a maximum attempt every round.
O2 Tables — Working at Lower Oxygen
O2 tables train the body to tolerate lower oxygen levels. The format is the inverse of CO2 tables.
The Format
Fixed rest interval → increasing hold time. The rest is long enough for CO2 to clear. The holds get progressively longer, pushing oxygen lower each time.
Example O2 Table
For a diver with a 3-minute maximum.
Start O2 tables only after you're comfortable with CO2 tables and have a reliable training partner.
Static Apnea Practice
The most direct form of breath-hold training — floating face-down in a pool, holding your breath for near-maximum duration.
Session protocol
- 01 —Buddy in position at the wall, watching
- 02 —2–3 minutes of calm preparatory breathing (not hyperventilation)
- 03 —Full inhale, face down
- 04 —Hold until first contraction — then continue as long as comfortable
- 05 —Surface on your own terms — don't wait for rescue
- 06 —Exhale on surfacing, three full recovery breaths, OK signal to buddy
- 07 —Minimum 4 minutes rest before the next hold
Start at 80% of your maximum. Maximal attempts every session leads to slow adaptation and higher risk.
Dry Training
Dry breath holds (on land) are safe to do alone and build CO2 tolerance effectively. They're typically 20–40% shorter than equivalent pool holds, but the adaptation carries over.
Useful dry exercises
- CO2 table sets
- lying still, watching a timer, normal preparatory breathing
- Walking apnea
- hold breath while walking at a normal pace — adds mild physical stress
- Box breathing between holds
- 4 counts in, 4 hold, 4 out, 4 hold
8-Week Progression
Track every session: hold times, rest intervals, contraction point, how it felt. The data tells you when to progress.