Preventing Shallow Water Blackout

Ella with Kim Rutherford, a U.S.A. Masters Swim Coach

What is Shallow Water Blackout? “You don’t realize that you need a breath, so you just kind of go to sleep underwater,” explains Kim Rutherford. “There’s no panic. [But since] you’re underwater, at some point your body tries to take a breath. When it does, it takes in water, and that causes a drowning.”

Rutherford is a U.S.A. Masters Swim Coach in California. I asked her about Shallow Water Blackout after a swim mentor who is close to me experienced it. He is an elite swimmer who competed at the Olympic Trials in 2012 and 2016.

How could a near drowning happen to an elite swimmer? To find out, I spoke with Rutherford, who was at the pool at the time of the incident.



Shallow Water Blackout is also known as hypoxic (low oxygen) blackout. It’s like fainting or passing out underwater.

When swimmers repeatedly hold their breath for a long period of time, or hyperventilate (breathe at an abnormally rapid rate), their carbon dioxide (CO2) levels become unnaturally low. This does not allow the brain to get the signal to come back up for air.

Already low oxygen levels at the time of a blackout are dangerous for swimmers. It can take only 2½ minutes for brain damage to occur. If not rescued quickly, a swimmer could drown. Even if lifeguards are watching, it’s difficult for them to detect unconscious swimmers from above the water.

Blackouts can happen to anyone who is holding their breath underwater. This includes everyone from children playing “hold your breath” games to elite swimmers.


“Never swim alone,” Ella reports. “Always have a swim buddy.”


In February of this year, my mentor was working out at a local community pool under the supervision of Rutherford. The lifeguard on duty was aware and watching as the swimmer did repeated 75-yard (3 laps) breath holds. The swimmer informed Rutherford that he planned to do 100 yards (4 laps) underwater with no breath. After taking a series of shorts breaths, he began his underwater swim.

“I remember pushing off for the fourth lap,” the swimmer, who does not want to be named, recalled. “I knew that I was short on oxygen, so I tried to make it quick with some faster kicks. About halfway through that lap is the last thing I remember. The next thing I knew, I was waking up on deck.”

Rutherford was watching the swimmer as he did his laps. “I could see him out of the corner of my eye as he went into the wrong lane,” she said.

Since the swimmer was still coming towards the wall, Rutherford did not signal the lifeguard to blow the whistle. Instead, she called to another Masters swimmer to go down and check on the athlete. The lifeguard, meanwhile, was watching for a sign from Rutherford.

When the Masters swimmer came up from the pool, she reported that the elite swimmer was unresponsive.

“My hand went up,” Rutherford said. “The whistle blew. Everything was in place.”



The Masters swimmer was instructed to go down and pull up the swimmer. But she could not do it alone. Three additional swimmers had to help bring him up from the bottom of the pool.

On the deck, the swimmer was purple from his face to his chest. His eyes were open and fixed as two lifeguards started to do CPR and mouth-to-mouth resuscitation. After three sets of 30 compressions and breaths, the swimmer regained consciousness. He recovered fully and has returned to regular workouts.

“I did everything as quickly as possible, and I did everything right,” Rutherford said. “The timing was perfect for everyone who was involved.”


Signs should be posted at pools to remind swimmers to limit the amount of time they hold their breath underwater.


Here are tips to keep in mind for everyone who goes into a pool, whether you’re a recreational swimmer or an elite athlete:

  • Never swim alone. Always have a swim buddy.
  • Never ignore the urge to breathe.
  • Let your coach or a lifeguard know that you’re holding your breath.
  • Have a limit for yourself. (One breath hold for one lap only.)
  • Never play breath-holding games.
  • Post signs at the pool to make people aware of the dangers of Shallow Water Blackout.


Photos courtesy of the author