We play a game called “swim golf” that involves some hypoxic work.
You get 1 point for every second it takes you to do the 50, 1 point for every stroke taken, and 2 points for every breath–lowest score wins. My best score in a short course meters pool (25m down and 25m back) is 50. 33 seconds, 13 strokes, 2 breaths.
The lowest possible score is about a 25. One of the Team Elite guys at MAC can kick a 50 underwater in 25 sec w/o breathing
just be glad the sign didnt say that you were not permitted to swim one lap underwater…would have been so confusing
its one time down btw
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just be glad the sign didnt say that you were not permitted to swim one lap underwater…would have been so confusing
its one time down btw
So now a lap is when swim to the bottom of the pool? This is getting ridiculous. We need to agree to all new “seminal swimming jargon”.
From now on, swimming from one end to the other (no matter the length) will be known as a “stretch”.
There and back is a “scratch”.
Around the perimeter will be a “swirly”.
To the bottom is a “depth charge”.
If you do an entire “stretch” under water it is called a ZackLap.
Here is the real reason you shouldn’t go under water at all…because this rule isn’t enforce:
Hmmmm, my pool is always cloudy.
Wow, wish I would have known about this 55 years ago when I started swimming at the local public pool at the age of 5. I use to swim under water from one end of the pool to the other. Thought I was pretty cool. Well I learned my lesson and I won’t do that again;-)
Shallow water blackout should never be an issue in a pool, which is far too shallow. SWBO happens when someone dives to a depth that significantly raises their oxygen partial pressure (PPO2). Due to the higher PPO2, you don’t feel the need to breathe as soon (and hyperventilating enhances this effect), and then as you begin to surface your PPO2 drops rapidly, starving the brain of oxygen and hence the blackout. I really don’t see how you could ever get deep enough in a normal pool for this to be a concern.
-David
I can’t believe I’m defending he hall monitors on this. Your post is so wrong in a couple of ways. If you’re joking then I’m not sophisticated enough to get it.
First, SWBO is just that. Shallow Water Blackout. You don’t even need to be under water at all (it’s just that it’s dangerous when in water). As I have stated in a previous post I have blacked out many times from holding my breath, NEVER IN THE WATER! I’ve done it on my couch. I’ve done it on a spin bike. I’ve done it laying in bed.
Second, partial pressure concentration issues only occur when you are breathing compressed air at depth (scuba diving). These free dive world record guys sometimes use compressed air and run into issues related to that. One of the problems is O2 toxicity. Over a certain depth the concentration of O2 is so great it becomes lethal. Fortunately, this happens at a depth greater than you can use normal compressed air due to the nitrogen problems. But that’s all useless info here.
Bottom line, you can pass (and I have done so) pass out without water and it is certainly possible in a pool.
Again, if you were joking, sorry.
All due respect, Duffy, but you are the one off base. I’m not joking at all, and while I certainly don’t profess to be an expert, I do have some experience with this from years of teaching scuba diving. It all comes down to basic physics and biology. From the physics perspective, look at Doyle’s, Dalton’s and Henry’s laws pertaining to gasses. From the biology perspective, keep in mind that the body, and particularly the brain, relies on the partial pressure of oxygen as opposed to the percentage of the gas for metabolic functions.
Oxygen partial pressure issues are definitely not limited to diving on compressed gases. Sure, it’s true that oxygen deprivation to the brain will cause blackout at any depth or at the surface, but the biggest single cause of shallow water blackout is skin diving and passing out while at depth, typically while rising to the surface. To better understand this, perhaps an example is in order. I’m going to use 33ft/10m (2ATA) as the depth, since it makes the math simple.
At the surface (1ATA), the skin diver takes a breath containing approximately 21% oxygen. According to Dalton’s Law, the PPO2 is (1ATA* 0.21), or 0.21. Since the brain requires a PPO2 of at least 0.16 for consciousness, no problem. Now the skin diver descends to 33ft/10m - the PPO2 is now (2ATA * 0.21) or 0.42. The diver now swims around for a bit, and the oxygen in the body gets metabolized and begin to drop, let’s say to around 0.2, still enough to keep the brain conscious. Now the diver begins to ascend, and as the ambient pressure decreases, the PPO2 drops. Say the diver is now at 16.5ft/5m, the PPO2 would now be (1.5ATA * 0.1) or 0.15. This level is now below the level the brain needs for consciousness, and blackout is a very high likelihood.
Someone pointed out that hyperventilation is the cause of shallow water blackout - this is also not technically correct. It’s true that hyperventilation is often associated with shallow water blackout as by flushing out CO2 from the lungs before descending, the diver’s urge to breathe may be delayed until after the critical point at which the PPO2 drops to a level where blackout can occur. Avoiding excessive hyperventilation is certainly a legitimate way to minimize the risk of blackout, but hyperventialtion is not the root cause.
You correctly point out that you can blackout at the surface without even being near water. This is not shallow water blackout, but simple oxygen deprivation. The PPO2 still applies, it’s just that the ambient pressure never goes past 1ATA. Of course, if you black out and you’re in the water, you run a very high risk of drowning, which is why shallow water blackout is so dangerous. Blacking out by holding your breath on the couch is a pretty silly thing to do, but as soon as you lose consciousness your brain will come to your rescue and restart the breathing process by itself.
Regards,
David
Yup. You’re right. Thanks.
Look up “shallow water blackout.” It’s no joke.
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The hyperventilation is really where the added risk comes in. It doesn’t add more oxygen to your blood but it does apparently help you get the CO2 levels in your lungs lower than normal, making shallow water blackout a risk. In this case, the urge to breathe, caused by the CO2 levels doesn’t make you pop up before the lower O2 levels make you black out.
Shallow water is a greater risk when skin diving or apnea: at depth, the partial pressure of O2 can be high enough to sustain brain function even when the fO2 drops to say 4-5%; on ascending, as the ambient pressure decreases, the PPO2 also drops. This is the most common cause of blackouts.
Edit - it has been explained by a fellow dive instructor in a lot more detail than my short summary above.
From a risk point of view, I somehow doubt that swimming at 1-2m is going to present any kind of material risk for shallow water blackout, especially for a typical swimmer, who will most likely surface before his fO2 levels drop below critical levels.