TL;DR:
Bottom line is that it's (really) complicated, so you're not going to get a definitive answer to your question about height/weight/gender/age.
Also, be sure to read the conclusion at the end...
Dive reflex is probably up there as the biggest factor for breathhold time, along with initial amount of oxygen in the lungs. (More precisely, the onset of hypoxia is to do with partial pressure of oxygen as the breathhold progresses [which affects how well O2 in lungs diffuses into blood], and how well that O2 is getting delivered to the brain. So it depends on initial partial pressure of O2 in lungs [how much air/gas is in lungs and what percentage of that is O2], subsequent rate of oxygen use reducing the O2 hence reducing the partial pressure, and unrestricted blood flow along with level of CO2 [via Bohr effect] affecting amount of O2 that diffuses into cells. Also any changes to ambient pressure during the breathhold will change partial pressure, but that only really applies when ascending/descending.)
As cdavis said above, the 'lung volume' (as a rough concept, see below) is likely correlated (
on average) with height and general overall build, which initially suggests that someone taller might (
on average) take longer to blackout.
However, I'd also counter that by noting that increasing height (and weight) will typically mean you have more cells in your body, which would potentially lead to a higher oxygen usage. (The type of cells probably plays a role, too - more muscle cells, and of certain types, could mean higher O2 use? Also, I've no idea about comparative O2 usage of fat cells, nor even how much increased brain activity may potentially play into this - many things done by the brain are automatic/subconscious, but if you 'think [a lot] harder' does that very slightly increase the need for blood/O2 to supply the brain...??)
I'm not sure how these two effects (increased 'lung capacity' with size vs more cells with size) would play out against each other out, and there are so many other factors that are way more important from person to person, and even from day to day & hour to hour. But it does suggest that,
all other things being equal (which they're not...), you' might be better off short & fairly skinny (and with a small/inactive brain?!
), but with unusually large 'lung capacity' for your size!
I think the only way to really quantify the importance of these things would be through taking a huge number & range of people, hooking them up to numerous monitors, and measuring a whole load of attributes (height, weight, age, gender, muscle mass of various types, lung capacity [including comfort at various volumes - see below], blood gases, blood composition [i.e. types of cells], metabolism, heart rate, numerous fitness markers, etc.). Then you could maybe try to correlate those with several repeated dry static times taken over multiple days (and also trying to take into account any previous experience with breathhold).
A note about what we've loosely called 'lung capacity/volume'...
The lungs by themselves are often capable of holding a fair bit more air than you can actually breathe in, even when taking your deepest breath. What tends to limit it is lack of flexibility around the chest (and diaphragm?) That's one of the reasons serious freedivers will do various stretches to improve/maintain such flexibility.
However, even if you manage to take a deeper breath and get more oxygen into your lungs before a dry static, paradoxically,
that may not mean it takes longer to reach hypoxia!
You may well find that filling up with more air actually becomes less comfortable due to 'stretch-receptors' that increase the urge to breathe and bring on contractions sooner. This, in turn, can decrease your ability to relax and reduces the dive reflex so you end up using O2 more quickly. (Again, the stretching exercises mentioned above can help.)
Also, increasing initial air in the lungs (without being flexible enough) can lead to some 'restriction' within the torso that actually reduces the ability of the heart to circulate blood - even leading to blackout (potentially even at/near the start of the breathhold).
In conclusion, here are three final thoughts...
- It's unusual to be able to reach blackout during dry static, especially for a beginner. -For the vast majority of people, it becomes way too uncomfortable to maintain breathhold to a level of hypoxia that could lead to blackout (largely due to build-up of CO2 and contractions).
- I suspect the more you think about this question the sooner you would reach hypoxia/blackout during your dry static breathholds (even just reaching general discomfort & contractions earlier).
- It's not good that you try (or encourage others) to reach blackout anyway during any breathhold - it's not helpful.
I know that second point is difficult - telling someone to
not think about something is the best way to make them think about it!
Instead, try to train yourself to
actively replace the thought, and think of something else - specifically, something that helps you to relax. That may be some kind of happy non-stressful memory, or repeating a saying or song/chorus in your head that flows easily with no effort to remember. I've even heard that doing some mental arithmetic can help! (I guess some may find that more stressful...)
It's really up to you to experiment with different thoughts and see if you can find something that works for you - and that will also likely take some time and practice, so don't expect it to work straight away.
...here ends another essay by me...
