aid coaches must warn swimmers to be careful about trying to hold their breath for extended periods of time and not rely on lifeguards, who may not be used to seeing such cases.

"It must have been something massive. That man was a highly trained professional who lived in the water,

she pulled her husband from the pool and tried to resuscitate him until pool staff members and emergency workers took over.

he got into the family pool alone.

locked in a breath-holding position, one hand crossed over his chest and the other resting at his throat.

"Because we don't know to what extent this is an issue we are unable to specifically target user groups or activity sectors.

Family members believe Jack could have remained conscious if the periods between his underwater laps had been longer,

seconds to pull someone up before brain damage

he ignored his body's urge to breathe and lost consciousness.

"Such deaths are normally recorded as fatal drowning and therefore it is not easily identified," he said."We become aware ... only when these contributing factors are recorded by observers leading up to the unconscious event.

Mrs MacMillan said friends and family had been surprised by the cause of Jack's death and none had heard of shallow water hypoxia.

Exhaustion is a key contributor to blacking out underwater, as is exertion, which can cause oxygen levels to deplete more quickly than in a body at rest.

"This is something that every child is doing - adults are doing it," Mrs Washbourne said."Jack nor any of us knew the consequences of holding your breath too many times repetitively.

drowned in a metre of water in his backyard, a short distance from his mother

however, Alexander never surfaced after free diving without fins or a mask or snorkel.

mouth Swim Team Member Drowns During Endurance Training

"You can ignore your urge to breathe; you get endorphins,"

the training agencies provided a safe path for divers to take knowledge from ocean diving and apply it to cave diving

50-60 people die each year in the United States as a result of drowning while breath-hold diving. But wait, before you say “That’s a huge number,” let me point out that an estimated 90 percent of those deaths are by untrained divers,

“That’s why you need a safety lookout. When you’re both doing the activity, it’s not a safety lookout.”

underwater blackouts typically occur after a swimmer hyperventilates

The Navy’s “two-man rule” — training with a buddy — is supposed to reduce risk because each swimmer is aware of the other’s activities and can render aid if needed; however, a swim buddy can’t reduce the risk inherent in breath-holding, especially if participating himself, Losey noted.

as they were timing themselves to see how long they could hold their breaths, facing the clock on the pool deck.

pool facilities to ensure the proper posting of emergency-response plans and equipment.

posted in pool facilities expressly prohibiting breath-holding.

Losey said the Navy will now require a lifeguard or first-class swimmer to be present on deck at Naval Special Warfare pools for all conditioning swims other than laps

“Overconfidence is an ever-present risk factor.”

Marihugh and Lewis were conducting an off-hours workout at the pool by themselves.

breath-holding should only take place in a controlled setting under the supervision of trainers or

they had been warned not to do it.

deaths are completely preventable.

increase awareness and promote prevention,

His friends thought that he had gone inside to call his girlfriend, Laura Dobrosky, who was out of town

Whitner likely tried to hold his breath one last time unnoticed by those around the pool.

The group were swimming laps, racing each other and competing to see who could hold their breath the longest.

perseverance and determination he could accomplish anything, and he just about did

hold his breath for over 3 minutes

His death was caused by breath-holding or hypoxic training.