O₂ capacity.
Fixed recovery, increasing hold. Trains efficient oxygen utilization — the canonical O₂ progression for static-apnea freediving.
Every table below recalibrates to this number. Don't know yours? Leave it at 2:30 and adjust later.
The method.
O₂ capacity tables train efficient oxygen utilization across progressively longer static-apnea breath-holds. Recovery remains constant while hold time extends each round, teaching the body to glide deeper into the dive reflex with composure. Reserve O₂ tables for sessions when you are well-rested and well-hydrated — and only with a trained safety partner.
About this protocol.
What is an O₂ capacity table in freediving?
An O₂ capacity table is a static-apnea exercise where breath-hold duration increases each round and recovery stays constant. It trains the freediver's tolerance to lower blood oxygen and a calmer, more efficient mammalian dive reflex. Each round nudges the diver closer to a controlled hypoxic state — never beyond — culminating in a final hold that sits below the 80% personal-best safety ceiling.
How long should my final O₂ hold be?
No more than 80% of your static personal best, per the consensus safety rule across AIDA, PFI, Molchanovs, and Apnea Total. This site's three difficulty tiers calibrate the final hold to roughly 65% PB (Foundational, gentle), 75% PB (Standard, canonical intermediate), and 83% PB (Advanced, trained divers only). An absolute safety cap at 85% PB is enforced under all conditions — the final hold will never exceed that, regardless of difficulty or PB.
How long should I breathe up before the first hold?
Two to two-and-a-half minutes of calm, unforced ventilation before round 1, per AIDA / PFI / Molchanovs. The breathe-up engages the mammalian dive reflex and settles the autonomic nervous system. Do not hyperventilate — fast or deep breathing flushes CO₂ and removes the urge-to-breathe warning that protects against shallow-water blackout.
Should I train CO₂ tables or O₂ tables first?
CO₂ first. Carbon-dioxide tolerance is the foundation — it raises your urge-to-breathe threshold so longer holds become physiologically possible. Layer in O₂ tables only after four to six weeks of consistent CO₂ work, when contractions feel routine and your static PB is stable. Most freediving instructors structure a training week as two CO₂ sessions for every one O₂ session.
What is the mammalian dive reflex?
A set of automatic physiological responses — bradycardia (slower heart rate), peripheral vasoconstriction (blood shunted to vital organs), and a spleen-mediated release of extra red blood cells — triggered by breath-holding and cold-water contact on the face. O₂ tables train the body to reach a deeper, more efficient dive reflex sooner, which is the single biggest determinant of breath-hold capacity in trained freedivers.
Why does the final hold matter more than the total time?
The progressive ramp-up is just preparation; the adaptive stimulus happens at the deepest hold of the session, where the body experiences and learns from controlled mild hypoxia. Stopping the table short means losing that stimulus. Going past it risks blackout. Hit the prescribed ceiling and walk away.