On September 17 I returned to the ocean. I was nervous about the idea of going free diving again. The thought crossed through my mind that I'm already very lucky to have the experience of being 24m deep. I could quit freediving now with a cool notch on my belt without having to put myself at more risk. Why did I need to dive again?1
I had every reason not to go. Hiring a pro cost 80 bucks, I have to drive for an hour each way, I have to then take a 30 minute boat ride (which usually leaves me seasick), and then I have to hold my breath until my diaphragm starts automatically contracting. Seriously, why the fuck would anyone want to do that? I asked myself this question over and over again as I was packing my bags and getting ready to go.
Well I realized why I needed to dive when I arrived at 15m below sea level. I floated there at zero gravity, an experience known only to divers and astronauts. And I heard the most beautiful noise, the calling of whales welcoming me to my home, the ocean. I floated there experiencing incredible bliss as I gave a thumbs up to my safety diver. I didn't have the slightest urge to breathe at any point during the dive.
Poseidon left me a parting gift - after diving, my hands were feeling much better! And although it may just be a fantasy, I have a reason to believe that freediving may help cure my RSI. Let me explain.
To do so, I must inform you about the most important aspect of the physiology of freediving. The astute reader of footnote 1 may be asking themselves how is it possible for freedivers to go to incredible depths of 100 plus meters? Wouldn’t their lungs shrink to a point, causing their rib cage to collapse?
The idea that one's rib cage would implode at a certain depth was a widely held myth for a long time. No one dared to test it. Legend has it that a drunkard dispelled the myth by doing the impossible in a public stunt dive to 50m. That his corpse would float to the top, or rather sink to the bottom, was a reasonable expectation. But who could have predicted that human mammals have a mechanism to pump the lungs with blood in order to prevent the rib cage from implosion under high water pressure? The drunkard was probably just a dumbass who got lucky as shit. His reckless stunt showed the world that free diving to great depths is possible.
The physiological phenomenon preventing the death of freedivers is called blood shift. It occurs as part of the mammalian dive reflex. When we submerge ourselves into deep water, blood rushes from the peripheries into our lungs so that the lungs can retain a rigid structure.2 it is undeniable that humans have aquatic roots.
Now to circle back to how this is connected with RSI. I have read that forms of tendinitis are caused because of restricted blood flow in the veins (i.e. - its an outflow problem). This causes swelling as the blood is unable to properly return home, possibly creating thick tendons that put pressure on nerves. Draining this blood may be an imperative.
I know it may be a fantasy, but could it be possible that blood shift from freediving can reduce some swelling that is causing pains my hands? I have a bit of evidence that this is the case, and I plan to explore that evidence further.
- Freediving is relatively safe compared to other extreme sports. There has only ever been one death in a freediving competition. Also, 24m is not deep for a competitor. People sometimes learn to free dive to 30m on the first day they try. With that said, at 24m the pressure is ~3.4 ATM. This means that your lungs are roughly one third the size that they would otherwise be due to Boyle’s inverse gas law. This is barring any effects due to blood shift which I will get to explaining later.
So idk man, I think freediving is pretty fucking gnarly! [↩]
- Unlike gas, liquid cannot compress into smaller volume no matter how much pressure is applied to the liquid's containing body. [↩]