Dead heat, silent but deadly?

Atri-athlete and marine biology major at the University of North Carolina, Wilmington, An excellent swimmer and student with a double major at the University of Illinois. A talented 10-year old summer sports camper at Indiana University of Pennsylvania.

What do all these swimmers have in common? They were all good swimmers in excellent physical condition. They were all good athletes and students. They were all high achievers and real competitors. And they all died while breath-holding, either on the surface or underwater.

This particular type of swimming death needlessly occurs for two reasons. First, most water safety personnel attend to the weak, novice, awkward, or non-swimming patrons at their facilities; the breath-holding swimmer seldom fits this profile. Second, the victims usually are unaware of the consequences of breath holding in the water; and, in fact, they believe this skill improves their overall swimming ability.

Undoubtedly, high risk individuals are the most likely to drown. Training manuals, orientations, and experience encourage the monitoring of high-risk patrons and activities. However, breath-holding individuals attract little attention from lifeguards because they do not appear to be at risk. But, in fact, this can be a very risky activity. Hypoxic training, underwater distance swimming, underwater races, underwater games, and even breath-holding contests can be linked to a significant number of deaths at aquatic facilities each year. But before further discussion of this problem, it is important to understand the psychology and physiology of breath holding and underwater swimming.

The Psychology of the Underwater Swimmer

Competition is an integral piece of the underwater swimming/breath-holding puzzle. Frequently, victims of this mishap are competing either against themselves or others. By attempting to swim farther than they have in previous attempts, they compete against themselves. When competing against others, they may be attempting either to swim farther or faster underwater than their opponents.

Victims of underwater swimming have been known to be high achievers who don't quit and who push themselves to the limit in many of their activities. They usually are good students in school.

Numerous survivors of near-death underwater/breath-holding swimming experiences provide similar stories. While breath holding either on the surface or underwater, they resisted the urge to breathe, an important sensation for survival, when they were starved for air. Their last thoughts were of swimming farther before compromising their predetermined goals. Survivors typically say they did not perceive any problems and even felt euphoric as they increased their distance underwater. They felt as if they could swim forever.

An important psychological consideration in this regard is the fact that brain ischemia (reduced blood flow), short of passing out, often creates a sense of excitement. Partial brain ischemia is thought to be one of the elements in creating certain types of psychological euphoria. This euphoria is accompanied by impaired judgment, and so it is easy to understand how unsuspecting victims succumb to the danger.

The Physiology of the Underwater Swimmer

Our urge to breathe is stimulated primarily by carbon dioxide [CO.sub.2], not a lack of oxygen ([CO.sub.2]). As long as the appropriate levels Of ([CO.sub.2]) are maintained, a sense of "air hunger," or need to breathe, does not develop. If [CO.sub.2] levels rise, we sense a need to breathe more. Mere are negligible amounts Of [CO.sub.2] in the air. Virtually all of our [CO.sub.2] comes from our metabolism. By way of example, during exercise, as our metabolism increases, so does our internal [CO.sub.2] level. Our respiratory rate increases, generally to match our [CO.sub.2] level to that of the air (which is close to zero). Thus we need to blow Off [CO.sub.2] while exercising. Since we are producing more [CO.sub.2] during exercise, the net effect is that the internal [CO.sub.2] level does not change very much. We know that a lack Of [O.sub.2] is not the stimulus to breathing as humans in a hypoxic environment with normal [CO.sub.2] don't experience an urge to breathe. Conversely, breathing a mixture of high oxygen with high C[O.sub.2] creates a sense of air hunger.

This control of respiratory drive by carbon dioxide perhaps was most dramatically demonstrated by airplane pilots of the past who -- in unpressurized cabins or without supplemental [O.sub.2] -- climbed to altitudes where the partial pressure Of [O.sub.2] is below the ability to adequately oxygenate the brain. These pilots suddenly and without warning "blacked out." Fortunately, many of them regained consciousness at lower altitudes with enough airspace to regain control and fly to safety. Hyperventilation "blows off' the [CO.sub.2], often to levels that are quite low; and this lack Of [CO.sub.2] suppresses the urge to breathe. At the same time, hyperventilation does not over-saturate the tissues with [O.sub.2] to any significant extent, so that there is no more reserve oxygen. [CO.sub.2] also regulates the flow of blood through the blood vessels of the brain. And as [CO.sub.2] levels rise, the blood vessels dilate, thus allowing more blood to flow to nourish the tissues. As [CO.sub.2] falls, the blood vessels contract, decreasing blood flow (ischemia) and -- in severe cases -- causing blackouts.

Most breath-holding swimmers either intentionally or unintentionally hyperventilate before commencing their swim. Hyperventilation (forcefully and rapidly inhaling and exhaling) lowers the percentage Of [CO.sub.2] in the lungs. When [CO.sub.2] levels are lowered, so is the stimulus to breath, therefore, hyperventilation enables swimmers to stay underwater longer.

While much has been written regarding the dangers of intentional hyperventilation induced specifically to increase breath-holding time, little has been said about unintentional hyperventilation which often can accompany these underwater activities. Unintentional hyperventilation often is caused by overexertion and/or excitement.

Hypoxic Training

Many competitive swimmers, particularly sprinters, train hypoxically, that is, they perform several maximum effort swims while holding their breath. This type of training is used commonly to build tolerance to the oxygen debt that develops during races. The huffing and puffing they do between bouts -- while attempting to recover -- actually is a form of hyperventilation that they cannot control. Overexertion causes swimmers to deplete their oxygen stores more quickly and also makes them less sensitive to the need to breathe. Hypoxic training in competition may be considered by coaches as a short-cut to conditioning, but it also can shorten lives. Loss of consciousness has been induced by hypoxic training in many competitive swimmers because it combines elements of overexertion and hyperventilation.

Shallow Water Black Out

Snorkelers also can hyperventilate inadvertently. While doing repetitive dives to take in underwater sights or practice swimming skills, they may "over-breathe" to catch their breath between dives. Another problem divers of ten encounter at extreme depths is that the increased water pressure increases the partial pressure of oxygen which, in turn, stretches their oxygen consumption as long as they remain relatively deep defined as greater than 10 feet, in most cases).

During the ascent to the surface, however, the partial pressure of oxygen is lowered, making it less available to the diver resulting in a possible black out. This diving phenomenon specifically is known as "shallow water black out."

Younger athletes may hyperventilate unintentionally through strenuous exercise, combined with the heightened excitement of participating in competitive games. The exertion that takes place during the games, coupled with the excitement of competition, may cause over-breathing. Again, in this case, too much oxygen may be consumed, while excess [CO.sub.2] is blow off, and loss of consciousness eventually may occur during underwater swims. This easily can occur during summer day camps or parties.

The position that a swimmer maintains in the water also may affect consciousness. Oxygen levels may drop while swimmers are completing long underwater swims in the horizontal position. While in the horizontal plane, the body suffers an oxygen reduction that is sufficient to effect the supply of oxygen to the brain. When the swimmer stands up, however, the blood supply to the brain may be reduced by the effect of gravity (orthostatic hypertension) and a black out may occur suddenly.

Therefore, considering all the psychological and physiological ramifications of breath holding in the water, we have a setting ripe for disaster. The final event in this chain of events may be drowning, cardiac arrest, or seizure.

Clearly, the way to eliminate the potential for tragedy is to educate all of those individuals who frequent aquatic facilities. Some suggestions include:

* Posting of warning signs.

* Education of the aquatic staff to watch for behavioral cues that include fit and athletic individuals repeating cycles of short rest-short swim behavior, obvious underwater swimming for distance or time, or small groups of individuals who seem to be "egging" one another on to take chances.

Supervision, Education Result in Increased Safety

Breath control and relaxation go hand-in-band and are integral parts of swimming and aquatic sports. To say that swimmers never should hold their breath while swimming would be counter-productive. If breath-holding activities are to take place during training activities, supervision is a must. All patrons -- as well as lifeguards and other staff -- must be alerted to and warned about the hazards inherent in breath holding, a seemingly innocent trick that can be deadly.

RELATED ARTICLE: My Hope Is That We Save a Life

Stephen Praisner, a collegiate triathlete at the University of North Carolina-Wilmington, died during public swim hours in his university pool at the age of 19. Although Stephen was an experienced swimmer, certified SCUBA diver, and lifeguard, he was found in a lap lane in four feet of water. In the following poems Stephen's mother expresses her grief and remembers the vitality of her child. She is a strong and determined force, who shares her private thoughts with us because" ...my hope is that the private connects with the public into a larger commonality. My hope is that we save a life."

College Pool

Night after night she's passed the

indoor pool promising herself she'll never look, but tonight she turns her head, her resolve not to bring it back, broken. She sees a young man like her son dive in and begin swimming. She wants to run in and whistle him

out. Doesn't he know he wouldn't be seen in those black trunks by the black line if he slipped under? She wants to tear the goggles from

his face. Doesn't he know they'd leave

engravings to the end? She wants to ask where all his buddies

are, she wants to towel him dry, she wants to say go home. Instead, she stands silent at the wall

of glass-- sees ancient wailing women beating their breasts, long black braids trailing down their backs.

Coming Home

On my lap, our son's blanket too bulky to pack, the smell of strawberry shampoo.

Beside us, his belongings in carry-on bags. We are crying.

"I travel light now," he bragged, going back to school two weeks ago, leaving bike and stereo behind.

We are two hours ahead of time in the boarding area-- we misread the tickets.

The security lady kneels by my husband, apologizes for making him open the bags, says she also lost a child--a little girl--a hit-and-run.

A man from the Piedmont counter speaks of a support group he attends, quietly maps out grief: where we are, where we must go, how to get there.

I cannot follow the low tones as he tells our other sons how it affects school work-- how he lost his son.

I cannot breathe, I am drowning too.

On the plane I read the paper a teacher gave me at the Memorial Service. "There's nothing special about me," our son wrote.

I begin a eulogy, writing on bags from the seat pockets the stewardess brings paper.

We carry home the weight and in the hold of plane, his body.

Shell

In and out the sea breathes green against the shore, a beach all mine this December day.

I find a mussel shell: blue, hinged, an empty house. I press it closed, hold the bivalve in my hand, keep the halves together. Seven

years

since we were broken open. Death

came as still water in a college pool, found you son, holding your breath that final lap in the seventh lane.

Now behind the dunes I step around a cover of hudsonia. Heathlike the undershrub holds fast despite its fragile roots--will live some seventy years if undisturbed.

References

Craig, A.B., Jr. (1961) Underwater swimming and loss of consciousness. Journal of the American Medical Association. 176:255-258.

Higgins, Paul. (1986) Hypoxic lap swimming -- a cause of near drowning. The New England Journal of Medicine. p. 1552.

Knight, Bernard. (1991) Forensic Pathology. New York: Oxford University Press.

Murphy, Marjorie, ed. (1994). On the Guard II : The YMCA Lifeguard Manual 2nd edition. Champaign, IL: Human Kinetics. pp. 116-118.