Bob Bowman & Baltimore’s Plea For Safety’s Sake On Shallow Water Blackout

The outdoor pool at North Baltimore Aquatic Club

The hidden danger of practising underwater breath-holding. This would be, said Bob Bowman standing next to Cathy Bennett (the woman who taught Michael Phelps to swim) and addressing the ASCA World Clinic in New Orleans, “pretty painful and personal … the most important information I have ever given to coaches”. In the interests of education and prevention, here is the story of Louis Lowenthal, who lost his life in the days after Shallow Water Blackout struck at NBAC

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The hidden danger of practising underwater breath-holding. This would be, said Bob Bowman standing next to Cathy Bennett (the woman who taught Michael Phelps to swim) and addressing the ASCA World Clinic in New Orleans, “pretty painful and personal … the most important information I have ever given to coaches”. In the interests of education and prevention, here is the story of Louis Lowenthal, who lost his life in the days after Shallow Water Blackout struck at NBAC


Clive Rushton

Craig, as you know I’ve tweeted this article under the instruction, READ ME!
I’ve always restricted my swimmers to a max of 50m with explicit instructions (COMMANDS!) not to try 75 or 100m. Question for the viewers: is 50 too much? Races ‘only’ allow 15m, so is our overload of 50m excessive or ok?


waow thanks for posting that article !! I thought it was ok to do laps underwater and I even like to try to go as far as possible underwater but never really considered shallow water blackout =s this really made me think =s I always associated drowning with people not good at swimming or electrical shock or whatever but never this =s

Such a horrible tragedy for a young boy who had his life ahead of him, life is so unfair sometimes =( RIP


My 9 year old son experienced a near-drowning in April 2012 while doing an underwater set of kicking hard with fins in a 25 m pool with his swim group at Toronto Swim Club. He fainted – the technical term is syncope – and went limp in the water. His coach jumped in to save him and so thankfully he was only unconscious for a few seconds. He was taken by ambulance to Hospital for Sick Children where he was thoroughly examined and sent home. A few days later he was examined and tested by a pediatric cardiologist who determined that he fainted because of he was exerting himself while holding his breath. It was very scary. I did not know until reading this blog entry that this type of incident was so common. We were lucky.

Craig Lord

Hi Catherine. I’m happy to hear that there was a good outcome in your son’s case. Thank you for sharing your story. By doing so and by raising awareness in the way NBAC is doing, there is a much greater chance of more outcomes like yours and fewer that go the way no-one would ever wish it to be.

Craig Lord

Clive. Thanks for raising those questions. I don’t have the answers … but no question that the sport should be thinking about it and finding the answers. As the article indicates, Bob Bowman watches a swimmer like Chase Kalisz the whole way when doing 50m underwaters – but no need or desire to do it with young children.

10 Reasons Why You Should Swim

Nice respond in return of this difficulty with firm arguments
and explaining the whole thing on the topic of that.

Bob Pratt

While the article is heartfelt and important it misses the most important information: hyperventilation. The problem is neither breath-holding nor swimming underwater. The links in the article are filled with inaccurate information that is not based in science.
Until we recognize the nature of the problem we will continue to have fatalities. Hyperventilation decreases the level of CO in the body but has little effect on the O2 level. It is a low CO level that triggers our urge to breathe NOT a low O2 level. Because the CO level is depressed (by hyperventilating) our urge to breath does not occur until the level of O2 has dropped below the threshold of unconsciousness.
Dr. Neal W. Pollock, Ph.D., Research Director, Divers Alert Network (DAN) and Research Associate in Anesthesiology Duke University Medical Center has studied, written and spoken about this phenomena and lead the National Drowning Preventions Task Force on “Breath-Hold Blackout”. The science is clear: swimming underwater and hypoxic training can be done safely IF coaches and athletes understand the physiology. The information that must be given to all coaches and athletes is that HYPERVENTILATION KILLS! Athletes can safely swim distances underwater and do hypoxic sets, so long as they DO NOT alter normal breathing while at the surface.
There is good information on the Wikipedia website that includes a graphic that is very helpful and guidelines to be followed by everyone not just competitive swimmers.

Bob Pratt
Great Lakes Surf Rescue Project

Bob Pratt

Correction on a misstatement in my previous post: It is the increasing CO level that triggers our urge to breath.

Craig Lord

Thanks for the post, Bob. It is appreciated, as are the efforts of all who seek to get it right on this. The references you provide are most useful and I would imagine that clubs and others are turning to many sources of expertise after this latest warning from a big program.

That said, it is not the job of an elite swimming website to delve into the detail of what happens in hyperventilation and Shallow Water Blackout. I note in the article that NBAC and ASCA will, in time, place the details of the presentation made in New Orleans on their websites. The presentation includes the details of what you list in your note. The presentation was far too fast flowing for me to accurately take down all the details of a very serious subject. As such, it is wiser not to try to get it half right (or half wrong…). I fully appreciate that internet information is not the source that clubs and others need to turn to when considering their safety plans (and that goes for Wikip too… your link to a place on the internet overblown with inaccurate info on many aspects of swimming). I posted the article to relate the alert given in New Orleans. Clubs and others concerned need to understand the detail of what happens, what the risks are and what Safety measures they can put in place. I offer links, as you do with Wikip, as a general guide – but none of that should be seen as the Bible on this subject, of course. I posted the links so that people can read more widely – but no-one responsible for safety should base their plans on any of that. They need to look more deeply (and I have now noted that in the article). I will alert readers as and when the detailed information shown in New Orleans is more widely available.

Kurt Schultz

Such a tragic story…I lost my sister about 30 years ago when she too collapsed and died on the pool deck after doing lungbuster training. the time we were told she had an arithmia or double heartbeat on apex. …but after reading this I wonder if diagnosis was correct all those years ago.

Cindy Blatt

This was a very tragic event that could have been prevented if there had been a coach on the deck.
I wonder if Mr. Bowman addressed the fact that there was no coach on the deck while this young
man “experimented” in the pool? Yes, there was supposedly a lifeguard on the deck but this young man
was the coach’s responsibility. Leaving the deck with swimmer(s) still in the pool is unprofessional and irresponsible. Mr. Bowman needs to address this with fellow coaches also – unless he thinks it is ok.

Craig Lord

Hi Cindy. I’m sure NBAC has looked at the issue of who is supervising when. The training set had finished. There were others in the pool, a lifeguard present. In many programs in the world, kids stay in the water and splash about after sessions. What no-one knew on this tragic occasion was that the young swimmer was about to repeat a breath-holding exercise many times over to try to improve himself in his own time after training. It could well have been that a coach was nearby – therefore I think it wrong to look back in hindsight and suggest that people were irresponsible and unprofessional when we have no idea as to the precise geography and flow of events on the day. The people at NBAC do know those things and have responded in a responsible way designed to ensure that the risk of a repeat is minimised to the lowest level possible. I’m sure both the parents of the young swimmer and NBAC have thought about a very wide spectrum of issues as a result of the tragic events of last October. The session had ended and – as someone who has swum in squads and watched squads the world over – it is easy to imagine that everyone thought that the squad had left the water (masters swimmers were in the pool at the time, for example, so it would not necessarily have been obvious that one swimmer remained in the water). Even so, CPR was being administered to the swimmer within two minutes… and he lost his life.


Thank you for your article Bob! I lost my 12 year old nephew to Shallow Water Blackout in January, still very raw, however we found out the hard way of what doing laps under water can do. Had no idea how dangerous it was, til it was too late and issued a name after we had advised Jack had been doing laps under water and sitting at bottom of pool at home whilst my sister, his mother was by the pool. He just looked like he was holding his breath, then realisation after seconds that he wasn’t appearing to have any movement at all…he had fainted and could not be saved.
To the general everyday family, clinical terms of hyperventilation, hypoxic blackouts etc are not a clear enough message to teenagers and to the everyday family. There was information being taught, only those who free dive and scuba dive are aware of SWB, which I find absolutely appalling.
I am fighting to ban, long breath holding in Aussie backyards and local pools, free divers should need permission and should they know the risks, and have their own support teams. To the average family unaware it pisses me right off that this is not educated to people outside of free diving etc.

I have started the awareness program in Australia, (Shallow Water Blackout Australia), have been in the media raising awareness and have started to work with Royal Life Saving to implement changes.
I have come across many families around the world who’ve lost loved ones to SWB, and have heard from near drowning experiences also.
I am working closely with Rhonda Milner and she has thankfully but regretfully educated me on most of what I now know.
Our Facebook Page is also doing well spreading awareness.

I hope I can save lives through awareness, education and simply teaching JUST DON’T DO IT!
I have learnt that breath holding IS NOT A GAME, and you are putting yourself at risk every time you embark on it.

please keep me posted on outcomes
Thank you
Sharon Washbourne
SWB Australia


Perhaps it will be helpful for coaches to have information about what is acceptable and what is not. Here is a possible example.

Approved types of training:
Ok to do series swimming where breathing patterns may be to breathe every 3,5,7, etc. strokes.
Ok to do 25’s on the surface of the water with the instruction, “If you need to breathe do so”.
Ok to do turn training where the swimmer works on “streamlining”. Keep in mind there is no reason for a swimmer to do 25’s or more underwater

What not to do:
Underwater swims beyond basic short streamlining training.
No underwater for length contests, or underwater for timed swims
No Hyperventilation prior to any breath holding training, even if “approved.”

Here is a resource that may be helpful.

Statement of the YMCA of the USA Medical Advisory Committee

The practice of extended breath-hold underwater diving has become a popular competitive
event but has significant dangers associated with it, including brain damage and death by
drowning. Individuals who perform this activity competitively train themselves to resist the
urge to breathe to see how far they can swim underwater while holding their breath. This
activity is not a safe practice in YMCA aquatic programs. To increase awareness and safety
within YMCA aquatic facilities and programs, the YMCA of the USA Medical Advisory
Committee recommends the following safety precautions and recommendations:
1. YMCAs should prohibit extended underwater breath-hold diving. For training purposes in
programs such as swim teams and skin/scuba diving, under the direct supervision of a
coach or instructor, moderate underwater breath-hold swimming that is normal and
reasonable is permissible.
2. Under no circumstances should a YMCA allow the practice of “static apnea” (where a
person is motionless underwater or facedown on the surface and holding one’s breath).
This activity is performed to see how long one can hold his or her breath. Due to the
extreme physiological danger of latent anoxia (blackout), this activity should be
3. Prior to any underwater breath-hold swimming, a coach or instructor should explain to
participants that hyperventilation (more than four rapid inhalations and exhalations) is
dangerous and should not be performed, and that the participant should exhale
periodically during the underwater swim.
4. At no time should even moderate underwater breath-hold swimming, snorkeling, or skin
diving occur without the direct, uninterrupted supervision of a coach or instructor.
Extended underwater breath-hold diving is not recommended at any time.
November 1999
Revised January 2004
November 2008
Reaffirmed February 2011

Lloyd Devigne

My son died while doing underwater swimming 22 years ago. He was a life guard and the other guards wee in the office after closing the pool, no one ws watching him . I hope this information prevents any more tragedy.

Dick Beaver, D.C.

Everyone go back up and re-read the notes by Bob Pratt, Sept. 11. He is right on the money. It has nothing to do with how far the swimmers swim under water. I used to limit my swimmers to only 3-4 deep breaths prior to any underwater or top of water breath holding swims. They also were treated to a discussion, every season, of the reasons, dangers, etc. And above all to never, ever do any breath holding swims without a coach present AND OBSERVING!!!!!

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