Holds and breath training

CO2 tolerance training: breath holds for the urge to breathe

By GyroscopeUpdated November 15, 202613 sources

Family

Holds and breath training

Breaths

Holds, no set pace

Carbon dioxide

Rises

How well tested

Unknown

Risk

Some

CO2 tolerance training is holding your breath on purpose, again and again, to get used to the urge to breathe. It comes from freediving, where CO2 tables string holds together with shorter and shorter rests. Holds do get longer with practice, and some divers end up less bothered by carbon dioxide, but nobody has tested whether it makes ordinary people calmer. The risk is blacking out, so it belongs on dry land, sitting or lying down, and never in water.

The online pitch is that the urge to breathe feels like panic, so if you train your body to tolerate more carbon dioxide, you’ll panic less and feel calmer all day. It’s easy to feel progress, too, since hold times climb fast. But in one Greek study, beginners’ holds got 46 percent longer in two weeks while their body’s response to carbon dioxide didn’t change at all. Longer holds can mean you’ve learned to sit with the alarm, while the alarm itself stays the same.

What it is and where it comes from

Freedivers train with two kinds of tables. In a CO2 table, the holds stay the same length the whole time and the breathing breaks between them get shorter and shorter, so carbon dioxide builds from one hold to the next. In an O2 table, the breaks stay the same and the holds get longer. Freediving Instructors International describes each table as eight short holds with limited recovery, “meant to be done as ‘dry land’ breathing exercises.” It says one or at most two sessions a week works best, and never a CO2 and an O2 table on the same day.

“Air hunger” drills are the gentler cousin, and they come from the Buteyko method. You breathe a little less than you want, through your nose, until you feel a slight, tolerable hunger for air. Buteyko Clinic International also teaches many small holds of 3 to 5 seconds, with 10 to 15 seconds of normal breathing between them, for coughing or calming the mind.

How to do it

If you train holds at all, these are the rules we’d keep.

1. Dry land only. Sit on a chair or the floor, or lie on a bed. Never in or near water, including the bath.
2. No big breaths first. Breathe normally before each hold. Divers Alert Network says hyperventilating before a hold raises the risk of passing out by delaying the urge to breathe.
3. Keep holds comfortable. A CO2 table keeps every hold the same and shortens the rests. Pick a hold you can repeat easily, well short of your longest.
4. Stop if you feel strange. Lightheaded, tingly or far away means the session is over. Breathe normally.
5. Once or twice a week. That’s the limit Freediving Instructors International gives, and never with O2 tables on the same day.
6. Someone nearby. Even on dry land, have someone in the room the first few times.

A simple way to picture it

It’s like living next to a railway line. The trains are just as loud as ever, but after a few months you stop jumping when one goes by.

What happens in your body

When you hold your breath, carbon dioxide builds up and oxygen falls. Rising carbon dioxide drives most of the urge to breathe, which is why lowering it first with big breaths delays the urge. Training holds teaches you to put up with that urge for longer. Meanwhile oxygen keeps falling, and Divers Alert Network warns that it can drop far enough to knock you out before the urge to breathe arrives. What happens when you hold your breath walks through the whole sequence, and carbon dioxide covers the chemistry.

A finger oximeter can’t warn you in time. In a Swedish study of seven men holding their breath during light cycling, finger sensors lagged ear sensors by about 15 seconds. When the ear showed oxygen at 78 percent, the finger still showed about 95. Your blood stays nearly full of oxygen for a long time, and once oxygen falls below about 60 mmHg, saturation drops steeply. oxygen.guide explains that curve in what the oxygen number means.

What the evidence shows

Most of the research is on divers, and it doesn’t all agree. In New Zealand in 1987, 34 underwater hockey players breathed less in response to rising carbon dioxide than 28 dry-land athletes did, which means they were less bothered by it. Their breath holds weren’t any longer, though. In France in 2001, eight trained divers were also less sensitive to carbon dioxide than eight non-divers. But in Croatia in 2008, 11 elite breath-hold divers who’d done about 76 training sessions that season responded to carbon dioxide the same way as 9 people who didn’t dive.

The Greek study tested training directly. Beginners did five maximal holds a day, two minutes apart, for 14 days. Their holds got about 46 percent longer, and their response to carbon dioxide didn’t change. The authors concluded that dulling it takes more than two weeks of training.

Nobody has tested whether CO2 tables or air hunger drills make ordinary people calmer. The closest work is on panic disorder, and it goes about it a different way. In a 2010 trial, 41 people with panic disorder spent four weeks learning to breathe slower and shallower with a carbon dioxide monitor, which brought their low carbon dioxide back to normal. Their panic improved about as much as with four weeks of cognitive training. When the same kind of training was tried in 2022 with 80 veterans with PTSD, their hyperarousal symptoms didn’t improve compared with a waiting list.

Who should skip it

Everyone should skip holds in water. The Red Cross, the YMCA and USA Swimming call passing out under water after hyperventilating “hypoxic blackout,” and StatPearls notes it can happen in any body of water at any depth. A CDC report found 16 people in New York State who blacked out underwater from breath holding between 1988 and 2011, and four of them died. All but one of the pool cases happened with a lifeguard on duty. Divers Alert Network says dedicated one-on-one supervision is critical even for laps underwater in a pool. Is holding your breath bad for you has the rest of that report.

Never do holds after fast breathing, like Wim Hof rounds, and never while driving. Skip breath-hold training if you’re pregnant, or have epilepsy, heart disease or blood pressure you take medicine for. Buteyko Clinic International adds an aneurysm, heart problems in the past three months, uncontrolled hyperthyroidism, a known brain tumor, kidney disease and sickle cell anemia, and says anyone with those should never hold past the first urge to breathe. The breath hold test times one comfortable hold, which is all most people need.