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.
Why?
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.
But…
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.]
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