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by Susan Dawson-Cook

August 29, 2016

The risks of breath-holding and how to use breath-control and breath-awareness

Learning to improve control of your breathing while swimming is a valuable skill that will enable you to power off the wall, put your head down at the flags to win a race, or not panic in open water when a wave splashes in your face. Breath-control training is intended to improve lung capacity and breathing efficiency in swimmers; however, it should not be confused with breath-hold training, which can be dangerous.

Some swimmers, including college athletes and Navy SEALs in training, have lost consciousness and drowned while holding their breath underwater. A 2015 report by the Centers for Disease Control and Prevention cited 16 cases of underwater blackout, four of which turned fatal. In all cases, the victims were expert swimmers engaging in breath holding.

It’s imperative for swimmers and coaches to understand the difference between breath control and breath holding, and understand the purpose of breath-control sets, how to perform them properly, and evaluate whether they’re safe to be performed. In short, swimmers shouldn’t be holding their breath underwater.

Cokie Lepinski, a Level 4 USMS-certified coach and the head coach of Swymnut Masters in Marin County, Calif., says “Breath holding makes for not only an exhaustive experience for a swimmer, but a potentially hazardous situation. As coaches we have to constantly work against the human body’s inclination to hold our breath when our face is in the water.”

Lepinski explains that the main difference between holding and controlling the breath is in the exhale. “In fact, I talk about how important it is to exhale each time your face is in the water. ‘Breath control,’ if not properly defined, is interpreted as ‘breath holding.’”

She also reinforces proper breathing and proper terminology when giving sets to her swimmers. “Instead of saying ‘swim a 25 and only breathe once,’ I’ll say ‘swim a 25 and challenge your breathing to a different breathing pattern.’ That’s great to get someone who breathes every stroke to try alternate breathing, breathing to the other side, or breathing every fourth stroke. Or, I’ll give them a set of 50s and encourage them to have race finishes with their heads down, no breathing from the flags in.”

And Lepinski is mindful of the competitive nature of many swimmers: “What I don’t do is allow 25s swum all the way underwater or any type of competition where they check in with each other to see how few breaths they took to get across the pool.”

Other sets that Lepinski gives her experienced swimmers focus on technique to improve their off-the-wall speed and efficiency: “I also like sets where lap one is underwater dolphin kick to tolerance before the swimmer surfaces to kick or swim. Even then, I’m reminding them that they need to pay attention to the urge to breathe. I use ‘to tolerance’ quite a bit and keep a sharp eye on anyone who may be pushing the envelope.”

The Science and the Risks

Swimmer, triathlete, former college basketball player, and emergency medicine physician Kip Kircher in Madison, Wis., agrees with the distinction between hold and control. “I think that most Masters swimmers can perform breath-control activities provided they are informed of how to properly do them, breathe when necessary even if they are not in compliance with the set, and are doing them in a supervised environment.”

The primary area of concern is shallow water blackout, which typically “occurs when a swimmer is restricting breathing to the point that the oxygen content in the bloodstream becomes too low to maintain consciousness,” Kircher says. For this reason, swimmers should never stop breathing during a set. They should consciously think about slowly exhaling air when the face is in the water and then breathe the instant the lungs have been emptied and the urge to breathe strikes.

Normally, “breathing provides oxygenation of the blood to supply the brain and other organs and allows the elimination of carbon dioxide. In healthy people, the signal to the brain that creates the drive to take a breath is a rising carbon dioxide level in the blood,” Kircher says. But this process can get derailed during breath-holding exercises because “while holding your breath, you are no longer ventilating, so you lose the ability to get rid of CO2.” Rising carbon dioxide levels cause “an increasingly powerful urge to take a breath,” he says. In contrast, falling oxygen levels do not cause that same urge to breathe. Instead, oxygen levels may fall low enough to cause one to pass out without warning.

In shallow water blackout, Kircher explains, “the swimmer is either resisting the urge to breathe for long enough to allow the blood oxygen to decrease to levels too low to remain conscious, or they hyperventilate before the set, driving CO2 levels so low that they run out of oxygen before the CO2 rises enough to stimulate the urge to breathe, and they pass out. A swimmer can also get into trouble by not allowing enough time between sets for the oxygen level to rise sufficiently, so that even with a few breaths between sets, they are starting off at a deficit that quickly becomes critical.”

In order to maintain bodily functions, our blood-oxygen levels—the amount of oxygen that’s in the bloodstream—needs to stay constant. Under normal, land-based conditions, that’s not a problem to maintain; the average person usually has blood-oxygenation levels well above 90 percent. However, that 90-percent mark is critical because once that downward threshold is reached, oxygenation levels drop off rapidly, Kircher says. “The oxygen/hemoglobin desaturation curve is not linear, and as a result, a swimmer can go from adequate oxygen saturation to poor oxygenation very quickly.” And you’re unlikely to feel it as it’s happening.

The chances of experiencing a dangerous drop in oxygen levels increases greatly for swimmers with certain health conditions such as COPD, emphysema, and asthma.

How to Use Controlled Breathing Sets Safely

Although Kircher says breath-holding sets are a bad idea, he sees value in breath-control sets. “Breath-control sets could also be called breath-awareness sets. The benefit probably comes from emptying your lungs with a long, slow exhale as much as possible, ridding your body of CO2. It also gets you accustomed to the discomfort associated with needing to take a breath. In my experience, increasing the number of strokes between breaths forces you to breathe in a more controlled manner, and alters your pacing so that you can actually perform the set.”

When performing these kinds of sets, Kircher cautions swimmers to “never hyperventilate before a set to try to improve your performance. It’s fine to exhale as completely as possible, inhale as much as possible, and then go, but breathing rapidly and/or deeply several times before the set is a bad idea.”

He also urges swimmers to use common sense. “When you become hungry for air, breathe. As you become more fit and more relaxed in the water, you will be able to go longer between breaths.”

Practicing breath-control or breath-awareness sets, under the guidance of an experienced and knowledgeable coach, is a safe way to for healthy swimmers to increase their breathing efficiency and improve their performance.


  • Technique and Training


  • Breathing
  • Safety
  • Injury Avoidance
  • Stroke Technique