From the pages of the Santa Cruz Sentinel:

"On Friday, September 27th, 2002, a 26-year-old man died swimming in the UC Santa Cruz pool. The man, an experienced swimmer, was doing laps underwater as part of a breathing exercise, a university spokeswoman and a lifeguard said. At about 7:30 p.m., a lifeguard saw that the man was still underwater but no longer moving. University fire officials and a crew of paramedics attempted to revive the man for more than a half-hour before pronouncing him dead at the scene.

Three lifeguards were on duty Friday evening, a head lifeguard said. The pool was filled with other swimmers as well as the school's water polo team, which was practicing for a meet Saturday, said Elizabeth Irwin, university spokeswoman."

While the coroner has not yet released the cause of death, it can be assumed that this is yet another case of Shallow Water Blackout.

I have written and warned about the dangers of underwater swimming many times since my son Wolf, nearly lost his life in our backyard pool in 1997. Nevertheless, since 1997, I am aware of six deaths that have come under strikingly similar circumstances as the one in Santa Cruz last week. Here's another recent example from the pages of the Washington Post.

"...On Friday, August 11th, 2001, Kyle Hurdle, a 21 year-old member of the US Naval Academy swim team drowned in a Newport News, VA pool. Hurdle was doing breath controlled laps at the pool when he went to the bottom. Lifeguards jumped in, pulled him out and performed cardiopulmonary resuscitation until a medic arrived. Hurdle was taken to Riverside Hospital and pronounced dead a short time later.

Tragically, no stories explain the cause or issue a warning about the dangers of underwater swimming and the phenomenon known as SHALLOW WATER BLACKOUT.

Shallow Water Blackout is most commonly associated with skin diving, but underwater fainting is not at all uncommon in the world of competitive aquatic sports.

The condition of Shallow Water Blackout is connected with the mixture of the carbon dioxide level (CO2) and the partial pressure of oxygen level (PO2) within the lungs. Individuals breathing under normal conditions use the partial pressure of oxygen in the lungs. Carbon dioxide, on the other hand, serves as a stimulus to breathing by informing the brain that a person's body requires another breath of air. This process occurs in any prolonged holding of breath, including underwater swimming. Normally there is no danger because the carbon dioxide build-up in the blood signals the brain that you need to take a breath by giving you the sensation that your lungs are going to burst if you don't get a breath. The problem comes when a swimmer or diver manipulates the brain's automatic breathing control device through

HYPERVENTILATION. Hyperventilation is the repeated inhalation of fast, full breaths of air and rapid exhalation. The effect of hyperventilation is to wash CO2 out of the lungs, resulting in an extremely low CO2 level. While the underwater swimmer burns up oxygen through exertion, (s)he never gets the signal from the brain -- the "bursting lung" sensation --because of the low level of C02 in the lungs and blood. Without the CO2 stimulus, the brain doesn't recognize the need to breath and the swimmer blacks out from a lack of oxygen to the brain known as hypoxia. The blackout victim is then in an extremely dangerous position at the point of unconsciousness. Seeing him underwater will fool observers as the unconscious swimmer often makes seemingly coordinated movements even after the faint comes on. He does not appear to be in difficulty. And irreversible physiological brain damage from a lack of oxygen, or cardiac arrest are only minutes away. (Frequently, I'm told, Shallow Water Blackout is often misdiagnosed as heart failure in the autopsy.)

I do not know all of all of the circumstances behind the most recent case in Santa Cruz, but I believe my son's near drowning in 1997 must stand as the classic example.

Wolf was challenged by his brothers to a contest of underwater distance swimming. As Wolf prepared to start, he'd take a few deep breaths and then burst out laughing, as the kids were shouting, splashing, jumping and teasing in an effort to prevent him from beating their combined distance record.. This scene was repeated several times before he finally took off - unconsciously and by circumstance - super hyperventilated. At some point, after being underwater for about a minute, and after he had surpassed the challenged distance, I heard the kids yell, "Dad, Wolf stopped.... He's pretending to drown." This sounded logical as both Wolf and

I had done this on occasion in the past. The kids then swam out to where Wolf was and proceeded to "attack" him. That's when they recognized something was wrong and called for help.

In talking to the kids after the incident, they initially thought nothing was wrong because "Wolf was moving." Wolf vaguely remembers the kids coming down to him and taking off his goggles. He had no recollection of "bursting lungs," of needing to breath or being in any type of trouble. It was like a dream.

Serendipitously, in my son's case, I was able to resuscitate him without any permanent physiological damage, although he felt after effects for many, many months.

Other fortunate survivors of Shallow Water Blackout have corroborated Wolf's dream experience. One survivor related to me his belief that in returning from the bottom while skin diving that he had made it safely to his raft, when in fact, his dive partner rescued him after he passed out ten feet below the surface and started sinking to the bottom.

Science can show no benefits for water polo or swimming from underwater training that cannot be duplicated in surface training. That said, kids love to swim underwater and it is not uncommon for them to challenge each other to underwater distance races. I urge you to take the time at the beginning of each season to warn each of your swimmers about the dangers of Shallow Water Blackout and hyperventilation and stress the serious risk of swimming underwater without a buddy or careful monitoring from above the water by someone who is fully aware of the dangers of shallow water blackout.