Holding breath for several minutes elevates marker for br...( BETHESDA Md. (August 4 2009) Divers...)

BETHESDA, Md. (August 4, 2009) Divers who held their breath for several minutes had elevated levels of a protein that can signal brain damage, according to a new study from the Journal of Applied Physiology. However, the appearance of the protein, S100B, was transient and leaves open the question of whether lengthy apnea (breath-holding) can damage the brain over the long term.

"The results indicate that prolonged, voluntary apnea affects the integrity of the central nervous system, and may have cumulative effects," the Swedish researchers said. The release of S100B into the blood suggests that holding one's breath for a long time disrupts the blood-brain barrier, they said.

The concern is that repetitive exposures to severe hypoxia (lowered oxygen supply), such as that experienced by individuals training and competing in static apnea diving events, could cause neurological damage over time. The researchers recommended further research on free divers that would begin early in their careers and follow them for years to monitor their neurological function.

The study is "Increased serum levels of the brain damage marker S100B after apnea in trained breath-hold divers: a study including respiratory and cardiovascular observations." The researchers are Johan P.A. Andersson, Mats H. Linr and Henrik Jnsson, of Lund University in Sweden. The American Physiological Society published the study.

There is a tradition of breath-hold diving in Japan and some other parts of the world that goes back hundreds of years, although the occupation has been dying out. These divers harvest seaweed, shellfish and other growth from the sea bottom, diving dozens of times per day. Some divers routinely dive to depths of 90 feet on a single breath while others dive in the 15-30 foot range.

More recently, breath-hold diving has become a competitive sport. Competitive events include how long div
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