Dmaziuk, thanks, I did not know that.
SeaRat
SeaRat
Underwater Swim Training- Shallow Water Blackout
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Technically free style is any style unless swimming the medley in which case it's any style other than butterfly, backstroke, or breaststroke. And front crawl is not a style with its own separate rules AFAIK. I am not making this up.
PS. on 2nd thought I think the medley thing may only apply to individual medley and not to relay.
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I'll have to look. I used to be a Stroke and Turn Judge for U.S. Swimming when my kids were swimming on teams. That was in the 1980s, and that 15 meter rule was not in effect at that time. I have two boys who were on the swim team, one of whom got very fast swims and qualified for the Junior Nationals. We took them to Maui, Hawaii where they also had a lot of fun snorkeling. I made a nice newspaper ad for the kids asking that they use PFDs when around the rivers in the summer. Feel free to copy it and use it anywhere. By the way, I did coach both boys on the hazards of breath-hold diving and SWB.
SeaRat
SeaRat
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TONY CHANEY
Contributor
Well as evidence has been presented it stands from the 1960's to present that hyperventilation to extend underwater time, thus decreasing your oxygen leads to deaths or anoxic brain injuries. If others really do not care to embrace the facts, then so be it. Mr Ratliff and I are just trying our best to explain something that can kill you very fast and something that you need to be aware of.
So the US Navy is also saying the same thing as Mr Ratliff and I are saying: http://www.detroitnews.com/story/ne...l-drownings-prompt-new-safety-rules/77257038/
So the US Navy is also saying the same thing as Mr Ratliff and I are saying: http://www.detroitnews.com/story/ne...l-drownings-prompt-new-safety-rules/77257038/
dumpsterDiver
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You are missing the point and you really should take back your comments about a BO necessarily leading to brain damage or Death...
This is just one video which popped up on YT about BO... The diver blacked out well below the surface and was recovered and revived quickly. It is essential that people understand that Black Outs are not always avoidable, but having a good buddy at the right place and right time can save your life. Hyperventlaltion to extend dive time is not recommended by any recognized training agency that I am aware of.
TONY CHANEY
Contributor
I was not trying to put myself down but I was just trying to be facetious. I treasure my profession and continue to build upon my knowledge each and every day. Mr. Ratliff and I both have listed several cases where death or brain injury did happen. You stated that we are incorrect and, "it has been proven thousands of times and refuted on a daily basis." Please provide us examples.
TONY CHANEY
Contributor
DumpsterDiver, the video you provided really does not tell us much. We do not know if it was contributed to hyperventilating and thus a hypoxic situation or a build up if excessive CO2 (hypercapnia). Symptoms of Hypercapnia are disorientation, panic, convulsions, unconsciousness and death. The symtoms of hypercapnia and anoxia may seem very similar and most, outside the clinical setting cannot tell the difference. I can bring back the majority of victims suffering from hypercapnia but not from anoxia. i.e. We had a code blue at the hospital last night and the blood gas was pH 7.04 and pCO2 was 120. After ventilation he was awake and alert later. So in you video, rescue breaths we given which increases ventilation and thus blowing off CO2. But, please keep in mind that rescue breaths only provide 17% oxygen which is far cry from what you really need...which is 100%. All in all, a very good video and very interesting to watch and glad with the outcome.
A few of things about this video bears mentioning. First I heard mentioned "2:15," which seemed to be a timer stating the time of this dive. Second, there were two rescue divers immediately available who brought this very lucky lady to the surface. Without them, she would have died. Third, we don't know how deep this diver was when the blackout occurred. I presume it was where we would now classify this as a deep water blackout upon surfacing, but we don't know that. Fourth, as soon as she was placed on the platform, they were prepared to give a mask (presumably with 100% oxygen). Rarely would a breath-hold diver have this kind of support. By the way, unless a MRI or CT scan is done on the brain, you cannot say there was no brain injury (see the article on Ama divers above).
Now, about the claim that "...it is essential that people understand that Black Outs are not always avoidable..." That simply is not true; they are always avoidable, and the diving technique used is critical in this avoidance. Not trying for records is one way, and using the rhythm method of acclimizing the body to breath-hold diving (which I detailed above) is another.
I also noted that the lady in the video did not drop her weights; many years ago (1960s), when we were spearfishing in Hood Canal and before any of the information was available or known, our small group (the Salem Junior Aqua Club, Affiliated with the Salem Aqua Club, Salem, Oregon), we decided that if we were at all concerned about reaching the surfsce and our buddy, we would unhook our weight belt and hold it in our hand. That way, if we did black out, we would automatically drop our weights. We were diving in about 15 foot (5 meter) visibility, and our buddy on the surface would not be able to constantly monitor our dive.
As. Certified Safety Professional, I can state unequivently that blackout are avoidable and that if it does happen, this indicates a breakdown in the dive technique. Yes, it is essential to train in emergency procedures in case of a blackout, and to take these precautions, but to make that statement created an atmosphere of inevitability, a self-fulfilling prophecy, if you will. It is also extremely poor teaching. It would be the equivalent of of saying to a scuba diver that decompression sickness is sometimes unavoidable when scuba diving. No, it is not, in either case!
SeaRat
John C. Ratliff, CSP, CIH, MSPH
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dumpsterDiver
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I'm no expert on freediving. I've taken only one, 1-day course which was a very abbreviated safety class. Freediving and the knowledge base has come a long, long way in 30-40 yrs. If either of the two of you had completed a freedive class in the last 5 or 10 years, you would not be asking for verification of information that is common knowledge.
You are incorrect about BO being always avoidable. In reality they are not, if a diver and especially a spearfisherman is pushing things at all.
The fact of the matter is that a BO can occur on just about any freedive and the smart diver (and his buddy) will always assume that it may occur. Important factors to reduce the chance of a BO include resting for a minimum of twice the duration of the previous dive, avoiding hyperventilation, resting well between dives- in other words, try to avoid vigorous swimming between dives, staying hydrated and of course limiting your exertion level underwater, your breathhold time and your depth to limits that are acceptable for the individual.
However, the important message needs to be that BO's are NOT entirely avoidable and they are NOT necessarily going to cause death or injury -- IF AND ONLY IF, a buddy is there to provide proper support.
This is a very important message! I scuba dive solo well past the recreational depth limits, but I avoid freediving alone and if I do find myself alone, I try to drastically reduce the aggressiveness of my breathhold dives.
Freedive spearfishing is very dangerous and there has been a very intense effort on the part of the various organisations to get the message out to dive with a buddy who will watch you as you surface and immediately afterward and to simply not dive alone.
The message is NOT that BO's are avoidable and if one should occur you are gonna be brain damaged or die. If this were the case, then the benefit of an attentive buddy would be negligible or nonexistent.
This website might be a good resource for anyone who is interested in safety.
http://divewise.org/
I dug out this video I shot with my head camera a few years ago. My buddy (and I) were engaged in competitive spearfishing in 85 ft of water and I was supporting him. It appeared that he was very close to BO in both dives shown, but I was attentive and positioned myself close enough to provide immediate support. On the second dive, I even descended myself to a depth of maybe 20 ft and escorted him for the final stage of the ascent. This may not be a perfect example of how things should be done, but it is the best one I have personally filmed.
I've done only one confirmed BO recovery and had no camera and the diver passed out at the surface (as usually occurs). The recovery and assistance provided was trivial and simple and quite possibly life saving. This is serious stuff. Gotta have a buddy - Don't assume a BO won't occur!
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adfitzer
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I, like DD, really don't think of breath hold swimming as having the potential for SWBO. However, SeaRat and Chaney do. It seems that everyone is in agreement that low paO2 is the terminal factor leading to the blackout. In breath hold swimming pre-submersion hyperventilation to induce hypocapnia is a crucial step in putting one's self at risk for a low enough paO2 to trigger blackout. Breath hold swimming is usually conducted in shallow waters; these blackouts occur in shallow waters thus I suppose I can see how the term shallow water blackout fits.
When I use the term shallow water black out, In my mind at least, the descriptor, 'shallow,' plays a more operational role which is really only achieved by free diving to depths and then returning to the 'shallows' which sets up the blackout due to the decrease in ppO2 of the lungs(leading to a reduced paO2) as a result of the reduction in ambient pressure with ascent.
That specific process does not occur with breath hold swimming as there is no change in the ambient pressure.
If one's definition of SWBO is simply hypoxia in shallow waters then blackouts that occur with both breath hold swimming and free diving would satisfy that definition and both be considered SWBO.
If one's definition of SWBO is hypoxia in shallow waters that results from reduction in ppO2 as a result of decreasing ambient pressure that occurs on returning to shallower waters from deeper waters then only a blackout that occurred with free diving and not breath hold swimming would be considered SWBO. This is how I personally understand the term SWBO.
I do not believe that blackouts are 'unequivocally.. avoidable' as SeaRat states. You can mitigate risk but you can never eliminate it. Regardless of the definition one holds, hypoxia and blacking out under or, around for this matter, water is a bad thing. Anytime any of us takes the risk of submerging whether on SCUBA, free diving or swimming, we are at risk for hypoxia, black out, and/or drowning. If we submerge we can NEVER completely avoid that risk. The consequences can range from fairly benign, as DD states, with simply your day of diving terminated, to deadly or leading to permanent morbidity like brain damage, as SeaRat and TChaney have stated. Some practices like hyperventilating prior to prolonged breath hold submersion is going to increase that risk.
I agree with DD that if you are going to put yourself at risk of blackout or any other potential danger, it is wise to build safety measures into your planned activity, and for him that means avoiding free diving alone and the 'important factors' he described above. The more risk one assumes, the more safety measures they ought to put in place.
I don't think I've read anything on this thread with which I factually disagree.I don't claim my interpretation of SWBO or my personal beliefs about risk management to be universal. I only submit them to add to the discussion so we can all become wiser and safer divers.
When I use the term shallow water black out, In my mind at least, the descriptor, 'shallow,' plays a more operational role which is really only achieved by free diving to depths and then returning to the 'shallows' which sets up the blackout due to the decrease in ppO2 of the lungs(leading to a reduced paO2) as a result of the reduction in ambient pressure with ascent.
That specific process does not occur with breath hold swimming as there is no change in the ambient pressure.
If one's definition of SWBO is simply hypoxia in shallow waters then blackouts that occur with both breath hold swimming and free diving would satisfy that definition and both be considered SWBO.
If one's definition of SWBO is hypoxia in shallow waters that results from reduction in ppO2 as a result of decreasing ambient pressure that occurs on returning to shallower waters from deeper waters then only a blackout that occurred with free diving and not breath hold swimming would be considered SWBO. This is how I personally understand the term SWBO.
I do not believe that blackouts are 'unequivocally.. avoidable' as SeaRat states. You can mitigate risk but you can never eliminate it. Regardless of the definition one holds, hypoxia and blacking out under or, around for this matter, water is a bad thing. Anytime any of us takes the risk of submerging whether on SCUBA, free diving or swimming, we are at risk for hypoxia, black out, and/or drowning. If we submerge we can NEVER completely avoid that risk. The consequences can range from fairly benign, as DD states, with simply your day of diving terminated, to deadly or leading to permanent morbidity like brain damage, as SeaRat and TChaney have stated. Some practices like hyperventilating prior to prolonged breath hold submersion is going to increase that risk.
I agree with DD that if you are going to put yourself at risk of blackout or any other potential danger, it is wise to build safety measures into your planned activity, and for him that means avoiding free diving alone and the 'important factors' he described above. The more risk one assumes, the more safety measures they ought to put in place.
I don't think I've read anything on this thread with which I factually disagree.I don't claim my interpretation of SWBO or my personal beliefs about risk management to be universal. I only submit them to add to the discussion so we can all become wiser and safer divers.
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