Competitive swimmers who hold their breath to...

Competitive swimmers who hold their breath to improve their performance may be increasing their risk of drowning, doctors have warned.

Researchers from the University of Virginia School of Medicine in Charlottesville, Va., described the case of a 19-year-old male member of the school’s swimming team who nearly drowned during training.

He was using a form of training known as “hypoxic,” which involves swimmers holding their breath for a number of laps to build tolerance to the lack of oxygen they experience during races, the researchers said.

Near the end of a three-hour workout, the swimmer was found motionless on the bottom of the pool after he attempted to swim the last 125 yards without breathing. He was rescued by a lifeguard and later recovered.

“Hypoxic training is commonly employed by competitive swimmers, but as our case illustrates, it may be dangerous,” the researchers said in a letter to the New England Journal of Medicine.

“We believe that prolonged ‘hypoxic’ lap swimming carries with it the potential for drowning, particularly in the highly motivated person,” they said.