Don't Hold Your Breath

Abstract

Competitive breath-holders can float face down in a pool for more than 4 minutes, and the world record is 11 minutes 35 seconds. That can't be good for their brains, right? To find out, researchers at Lund University in Sweden had nine trained breath-holders lie face-up on a couch and hold their breath to mimic the so-called static apnea pool competition. The breath-holders started with their normal warm-up routines: hyperventilation and “lung packing” (using tongue and throat muscles to force extra air into the lungs). Then they stopped breathing for an average of 5.5 minutes. The volunteers' blood oxygen levels dropped by almost 80%, and concentrations of the protein S100B—a standard marker for brain damage—increased by 37%, the researchers reported online 2 July in the Journal of Applied Physiology . S100B is normally found inside brain cells and fluid but seeps into the bloodstream when an injury disrupts the brain's protective blood-brain barrier. The breath-holders' concentrations were lower than those seen in stroke or traumatic brain injury patients, and the levels recovered after 2 hours. “We probably only saw a temporary opening of the blood-brain barrier,” says researcher Johan Andersson, but he warns that it is unclear if repeated barrier openings might produce long-term brain damage. Ralph Potkin, a pulmonologist at the Beverly Hills Center for Hyperbaric Medicine in Los Angeles, California, calls the findings “disconcerting.” But John Fitz-Clarke, a diving physiologist at Dalhousie University in Halifax, Canada, says that “it's way too premature to draw any conclusions about brain damage” from these findings.