Continuing our theme of exploring warrior facility in the aquatic environment, talk must be made of the “bends,” the intense dangers of this malady, and how a simple tribal method of timing thwarts this dire condition.
First, what exactly are the “bends”?
The “bends” have also been known as diver’s disease, and caisson disease. [Caisson disease being named for the watertight structures placed at depth to allow laborers to work on the foundations of bridges, dams, and tunnels.]
These slang terms are all referring to decompression sickness [DCS from here on out.] When working at depth or altitude [DCS can afflict those flying at altitude in non-pressurized flight suits or extravehicular activity-EVA-outside of spacecraft] the human body experiences extreme changes in pressure: water or air pressure depending on the medium.
If the human returns to standard pressure too quickly, dissolved gases, in particular nitrogen, comes out of solution and can form bubbles inside the body. Depending on the location of these bubbles and their volume they can affect the body in different ways, from headaches, to joint pain, to seizures etc. These symptoms are often acute and can be deadly.
To combat DCS, decompression chambers, pressurized suits, and complex ascent charts with specific decompression times have been concocted to thwart the dangers.
We see this danger primarily in divers and airmen who have the benefit of technological assistance to artificially increase the depths or heights the body can reach. In the case of the aquatic environment, we have air tanks to allow us to go deeper or to hang out longer at depth.
In the case of skin-diving [diving without apparatus] or free-diving [the sportive aspect where depth is the measuring benchmark] DCS is seldom a problem.
Even divers with extended breath holds are not submerged at depth long enough to allow nitrogen bubbling sufficient to make DCS a problem. This holds true even for divers who regularly reach 150 feet.
Skin-divers can and do suffer from DCS who make repeated depth-dives even if they are all of short duration.
[Side-Bar: In surveys of indigenous diving cultures around the world, the average length of a dive is around the 2-minute mark. Many can exceed this but either skill at the task being performed, say pearl diving, or accrued wisdom seems to keep the dives around 2-minutes. Working for breath holds much beyond this point may not be necessary or, in fact wise, we’ll cover that another day.]
In the South Pacific we find the Tuamotu archipelago. The indigenous peoples here are traditional pearl-divers with extraordinary diving ability. Amongst these divers there is a condition known as taravana. Taravana translates loosely to “fall crazily.”
If a pearl diver becomes afflicted with “taravana” he or she may experience headaches, visual problems, dizziness, paralysis, and even die.
Taravana is an ever-present concern. One observer reports that on a single day out of 235 pearl divers, 47 suffered taravana symptoms, many were mild but six of these individuals were paralyzed, and two died.
At first glance, it seems that we are seeing aspects of DCS but dive times still hovered at the 2-minute mark which would suggest that we should be well under the nitrogen bubbling danger.
And yet, clearly diving, even without apparatus can be extremely dangerous.
And yet…on the nearby island of Mangareva, which is also occupied by a pearl-diving culture the condition of taravana is completely unknown.
How can this be?
A separation of a few hundred miles, similar genetic make-up, same vocation/avocation and yet one culture is tragically plagued with disability and death and the other—nothing.
Turns out that taravana is indeed a form of DCS. It is triggered not by the depth of the dive, or the duration of the dive, but by the intervals between dives.
The Tuomatu pearl-divers make between 6-14 dives per hour. The depths are as great as 150 feet, and the average dive time is 2-minutes.
They remain on the surface for an average duration that lasts between 4 and 8 minutes.
Let’s look at what the divers of Mangareva are doing. Same average number of dives in a day. Same depths reached. Same average underwater dive-duration but…Mangareva tradition dictates that they remain on the surface between dives longer.
How much longer? 2 minutes longer. They remain on the surface for at least 10-minutes between dives.
A mere 2-minute difference between the Mangareva and the Tuomatu spells the difference between high injury/high fatality rate, and zero presence of taravana.
It is now known that taravana is another form of DCS. It turns out that repeated dives to depth with short duration between is too brief a time to allow the nitrogen to be cleared from the system. Repeated dives allow the nitrogen to accumulate and trigger DCS.
Whereas, a mere 2-minute longer wait between dives and nada.
With this in mind, we can take the wisdom of the Mangareva and Navy Frogman combat breath holding tactics and dive and swim better and with more safety.[For more on Indigenous Aquatic Ability see the articles in this blog "Ancient Hellene Frogmen & Combat Breath-Holding Tactics", "Aquatic Evasion", & "Hacking Visual Acuity the Sea-Gypsy Way."]
[For more Old School training practices subscribe to this blog, the RAW Subscription Service and our upcoming book Rough & Tumble Conditioning.]