As long as I have been freediving, no one has yet been able to give me clear answers regarding blacking out. I consider it perhaps the most important subject in freediving , but somehow it appears to me that instructors (mainly due to poor knowledge) often get uncomfortable discussing the matter in detail.
Although I am luckily not particularly prone to them, I would very much wish to understand their functioning in order to help keep myself and fellow divers safe.
We know that a breath hold does not need to be taken to the edge to black out, nor do we need to be going deep as it can of course happen in static or dynamic.
Do you know of any particular things to be careful of, or any warning signs to observe in order to stay clear of the blacking out zone ?
Thank you for your help.
this is of course a very big subject, and if we go very deep into details, a lot of what we think we know might actually be wrong.
However, this is not that important, as we do know that ultimately the reason why we have a black out is lack of oxygen (even though there are some new studies that suggest that oxygen might not be the real cause for BO we will stick with this theory until it will be scientifically disproved). So what you need to do is to make sure you dont get to the point where your oxygen level is so low that there is not enough to keep you conscious.
how do you do that? well, every time you go close to your limits you are taking a chance and you cannot know for sure that you will or will not black out. the only thing you can really do is to learn how to recognise the symptoms of low oxygen before it is too late, and stop your dive in time. of course this is easier to do if you are doing static or dynamic, and it is not so easy in open water, especially if you are at depth during a dive.
i find that people have different symptoms, or they become better at recognizing easily some symptoms while they are overlooking others. so the answer to your question is not as straightforward as you would like it to be:) if you are someone who trains for performance, you need to check yourself and towards the end of a dive really ask yourself ” how do i feel?” “do i feel something different” “can i think clearly?” “do i see clearly?”
as long as everything feels completely under control you should be fine. if and when you will have a LMC or black out (hopefully a very small one) you have a new term of comparison. you will remember how you felt then, just before it happened, and you will learn how to watch out for the same symptoms.
if you dive always with the same people, who hopefully are good freedivers and responsible buddies, their help can be very useful. they will see you coming up from a dive and they will know if you looked completely fresh or a bit tight, or you lips looked gray and your face hypoxic. Rely on their feedback, because what you feel sometimes is not necessarily how it really was; external feedback if coming from a source that you trust is the most objective feedback you can hope for.
personally i know that if i get hypoxic my thinking become confused and fuzzy; it’s very easy for me to recognized if i do static and my buddy is talking to me, because at some point i find myself thinking: “what on earth is he talking about??”. this is when i realize it’s not my buddy talking rubbish but it’s me who is drifting away and i come up immediately. in open water is not so easy, most of the times you dont really feel it coming, so the safest thing to do is to progress very slowly, conservatively and by doing repetitions, which takes time and you still dont know for sure that you will not black out, because sometimes you simply have a bad day and maybe you dont realize it and you will do a dive that yesterday was easy, but today you have a black out. it just happens!
i hope i was able to add something useful to your knowledge:)