WEDNESDAY, Aug. 5 (HealthDay News) -- Divers who hold their breath for several minutes have elevated levels of the protein S100B, which is a marker of brain damage, according to a study published online July 2 in the Journal of Applied Physiology.
Johan P.A. Andersson, Ph.D., of Lund University in Sweden, and colleagues had nine trained breath-hold divers perform a protocol that mimicked procedures they use during training and competition, including pre-apneic hyperventilation and glossopharyngeal insufflation so they could perform static apnea. The researchers also used six non-divers as controls.
The average breath-hold time was five minutes, 35 seconds. The researchers found that S100B levels increased in seven of the nine divers but none of the controls. S100B levels rose 37 percent, on average, within 10 minutes after apnea ended, and levels returned to normal within two hours for all study participants. The researchers also note that the elevated levels of S100B were still well below those associated with brain injury and that the elevation was more transient in divers than in people who suffered brain injury.
"It is not possible to conclude that the observed increase in S100B levels in serum after a maximal-duration apnea reflects a serious injury to the brain, although the results raise concerns considering negative long-term effects," the authors write. "At least, the results indicate that prolonged, voluntary apnea affects the integrity of the central nervous system, and do not preclude cumulative effects."
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