Quote:
Originally Posted by fcallagy
Definitly post it Alix I am sure we would all be interestred to read it.
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Sure thing. it's long, so if you can't be bothered then don't worry. On the other hand if you have any suggestions or notice that i've made a mistake please tell me!
This is without abstract.
A comparison between the physiological chatacteristics in human freedivers and marine mammals
Introduction; my personal interest in freediving
I've always been familiar with the ocean and diving and have clear memories of my father’s fins disappearing under the clear blue and surfacing again a few minutes later, a 6kg sea bass still struggling on the end of his spear gun. I first started scuba diving when I was thirteen but like many freedivers found the equipment to be uncomfortable, limiting and sometimes gets in the way of what you've actually come to see. For many years I had heard about Luc Besson's film "The Big Blue" and only in 2006 did I finally have access to a copy. Already very interested in diving and the ocean, after watching the film I began my freediving training in February 2007 with help and advice from people on the deeperblue.net site, to which I and many other freedivers are indebted. Much more complex than I first imagined, training for freediving requires physical skill and fitness as well as constant attention, motivation and focus down to what one eats on a daily basis. Apart from the physiological training, which for the most part involves training ones body to be comfortable and progress with breath-holding, there is a very important psychological side to be understood and controlled. Similarly to biofeedback, freedivers must learn to slow their heart rate, remain very calm and relax the body and mind so that the mammalian diving reflex can kick in and be developed. I would have liked to explore many aspects of freediving in this essay which have been omitted, including training techniques and the physiological effect they have on the body, as well the sensations that occur during apnea (breath-holding), diet and a discussion of the psychological benefits from apnea. However, given only 4000 words I have decided to concentrate on the main physiological characteristics that allow us to freedive in comparison to other marine mammals.
An introduction to freediving
Also known as breathhold diving or skin-diving and often misconstrued by the media as being a dangerous and thrill seeking obsession, freediving is actually one of the most relaxing and natural sports that exists. At its most simple, freediving is simply diving underwater without any other breathing apparatus than your lungs, although the sport is split between different disciplines. Constant Weight is one of the most popular, whereby a person swims (often down a line) under their own strength with or without fins. It is similar to Free Immersion except in this a freediver does not have any weights and actually pull themselves down the rope instead of swimming. The most challenging form of freediving is No Limits, whereby a freediver either holds or is attached to a sled that pulls the diver down a rope at a usual rate of 3m/s to very deep depths, always supervised by safety divers, and returns to the surface by aid of an air filled balloon. Freediving has its roots in ancient fishing and many freedivers today are also spear-fishers, hunting prey underwater on one breath using a metal spear ranging from 40cm to 120cm.
Many freedivers remain openly philosophical about the link between freediving and our prenatal experiences or ancestral linkage whilst some have said to experience such a deep relaxation whilst diving, caused not by hypoxia or pressure but triggered by our mammalian diving reflex, that many have linked it to what Buddhists know as nirvana. "Possibly these experiences are the psychological by-product of the dive reflex working in full, designed to protect us by keeping the body calm and peaceful during deep dives... their descriptions closely match those of mystic and religious traditions that aim to profoundly alter their mental states through deep meditation» (The "Zen" of freediving [online] Available at
The Greater Meaning of Water [Cited 11 July 2007]).
A brief history of freediving
Historically, the exact origins of freediving are unknown although many people including archaeologists believe that Neanderthal man probably depended as much on the oceans for food as they did on land. Some early records dating back to 4500 BC suggest that Mesopotamians dove for pearls, as some Japanese, Korean and Philippine women do today. Of these, most commonly known are the Ama divers, famous for pearl and abalone hunting, who repeatedly dive from 10 to around 20 metres and can spend one minute twenty seconds prising shellfish off rocks. Some of the younger women can carry on this activity for up to four hours without wetsuits or any other protection against the cold.
The first record of a deep dive dates to 1911, in Karpathos, where the Regina Margherita lost her anchor at 77 meters. In one day alone, a Greek sponge fisherman Yorgos Haggi Statti successfully managed to dive three times to the depth of 77 meters to pass a rope through the anchor, even though he had pulmonary emphysema. (History of... [online] Available at
http://forums.deeperblue.net/general...0-history.html [Cited 11 July 2007) Nowadays, freediving is practiced by more than 20,000 people globally ranging from snorkelling, spear-fishing and worldwide competitions.
One of the most interesting group of modern day freedivers are the Moken people of the Andaman sea; sea gypsies with no nationality or permanent residence. They are born, live and die on their boats, coming to land only to sell the fish they catch using homemade spear guns and nets to pay for fuel to power their boats. They are truly unique. Their children learn to swim before they walk, they can see twice as well underwater as anyone else, and they have a very developed and powerful dive reflex that can allow them to consecutively dive to 20 meters for two minutes, and feel so at ease on the ocean that they reportedly feel "land sick" when coming aground.
Competitive freediving began in 1949 by Raimondo Bucher who dove to a depth of 30 meters. He was soon followed by several other competitive freedivers including the legendary Jacques Mayol (as popularised in the cult film "The Big Blue") who was the first man to break the 100 meter-barrier in 1976, and was later beaten by Angela Bandini; the first woman to break a man's record at 107 meters deep. The current world record is held by Herbert Nitsch at 214 meters and who aims to reach 1000ft (305 meters) before retiring (Projects [online] Available at
Extreme Freediving [Cited 11 July 2007]).
Freedivers continue to break world records that were previously thought to be impossible, since the human body would be unable to withstand such pressures and lengths of time on a single breath. However, the body’s adaptations under such conditions continue to amaze biologists who only until recently realised to what level the body can compensate for insufficient oxygen and pressures up to 22 times what we feel at sea level.
