Holding breath for several minutes elevates marker for br...(and breath-holding warm-ups. The res...)

The researchers took arterial blood samples from a catheter inserted into the artery that runs through the wrist. They took samples before the breath hold, at the end of the breath hold and at fixed intervals for the two hours following the end of the breath hold. The researchers also measured arterial blood gases. They did the same measurements on the individuals in the control group, but the controls rested on their backs for the entire experiment, without performing the breath hold or the warm-ups.

Among the findings of this experiment:

• The average breath-hold time was 5 minutes 35 seconds. The longest was 6 minutes 43 seconds and the shortest was 4 minutes 41 seconds.
• The marker for brain damage, S100B, rose in seven of the nine divers.
• The controls showed no change in S100B
• On average, S100B rose 37% within 10 minutes after the apnea ended.
• S100B levels returned to normal within two hours for all the participants.
• The divers showed signs of asphyxia, that is, blood oxygen levels fell, while carbon dioxide levels rose.

The S100B levels, while elevated, were well below levels associated with brain injury. In brain-injured patients, the presence of S100B in the blood can increase by several hundred percent.

In addition, the elevation of S100B was more transient in the divers, compared to people who suffered brain injury. The divers had a quick return to normal, while S100B levels peak in 24 hours in brain-injured patients.

The transient nature of the increase in S100B among the divers probably indicates the blood-brain barrier has been compromised, allowing the protein to escape from the fluid in the brain into the circulation. The blood-brain barrier controls what passes between the brain and the circulation. S100B would normally remain in the brain.

Other sports have also been associated with a similar transient increase in S
'/>"/>