No Limits Freediving

1 No Limits Freediving "The challenges to the respiratory function of the breath-hold diver' are formidable. One has to marvel at the ability of the human body to cope with stresses that far exceed what normal terrestrial life requires." Claes Lundgren, Director, Center for Research and Education in Special Environments A woman in a deeply relaxed state floats in the water next to a diving buoy. She is clad in a figure-hugging wetsuit, a dive computer strapped to her right wrist, and another to her calf. She wears strange form-hugging silicone goggles that distort her eyes, giving her a strange bug-eyed appearance. A couple of meters away, five support divers tread water near a diving platform, watching her perform an elaborate breathing ritual while she hangs onto a metal tube fitted with two crossbars. A few meters below the buoy, we see that the metal tube is in fact a weighted sled attached to a cable descending into the dark-blue water. Her eyes are still closed as she begins performing a series of final inhalations, breathing faster and faster. Photographers on the media boats snap pictures as she performs her final few deep and long hyperventilations, eliminating carbon dioxide from her body. Then, a thumbs-up to her surface crew, a pinch of the nose clip, one final lungful of air, and the woman closes her eyes, wraps her knees around the bottom bar of the sled, releases a brake device, and disappears gracefully beneath the waves. The harsh sounds of the wind and waves suddenly cease and are replaced by the effervescent bubbling of air being released from the regulators of scuba-divers. Bright beams of light illuminate her as she descends on the sled at an alarming rate, hanging on like a ribbon in the wind, her I-m-Iong carbon fiber fins fluttering like the wings of an insect. The platform soon disappears from sight as she plunges faster, faster, into an immiscible abyss, the crystalline light fading at a rate of more than 2 m per second. A marker at 30 m is reached in a matter of seconds as two safety divers watch from a distance. Four atmospheres. At this depth, the pressure 1 The more common term is "freediver", which is used throughout this chapter. 4 No Limits Freediving would squeeze a balloon to only one-fourth the size it had been on the surface. All is silent except for the occasional click-click of a nearby dolphin witnessing this surreal aquatic performance. Her depth gauge reads 60 m. Seven atmospheres. Everything around her is a dark blue. She spots two more safety divers, one of their spotlights trained on the aquatic human descending the plumb line to the darkness below. The divers look clear and sharp but their colors appear washed out into bluish grays like an old black-and white film shown late at night on a bad television set. She hits a thermocline, the ocean's deep icebox layer, and the water temperature plunges to 7°C, immediately numbing her lips and cheeks. Dark blue shades to black. Points of light brilliance occasionally dance in front of her eyes. Phosgene. This is deep. Very deep. Like a human torpedo, the aquatic human closes on the next marker at an astonishing rate. 150 m. This is below the crush depth of many World War II submarines. 170 m. Already, she can feel the strain in her respiratory system as carbon dioxide starts to build in her muscles and organs and is taken away in her bloodstream to her lungs. She appears serene as she clutches the sled to the infinity below, apparently oblivious of the remarkable changes occurring in her body. Her lungs have already been crushed to the size of an orange and her heart is barely beating. The blood shift occurring at these depths means her spleen has pumped out a mass of extra blood cells, her blood vessels have collapsed, and blood has been forced out of her limbs into the space where her lungs should be. The elapsed time since leaving the surface is now I min and 10 sec. 180 m. She is experiencing a crushing 19 atmospheres of pressure but the sensation is strangely comforting. Almost sedative. She continues her descent into the submarine night, a silky silence broken only by the rhythm of her heart slowly beating. Her wetsuit is now compressed paper-thin and the pressure in her eardrums builds to a mild pain that rapidly becomes intense and then quickly unbearable. She feels as if her ears are about to burst. Looking down, she spots two more safety divers illuminating a small platform and she slows the descent imperceptibly, checking her hold on the sled as it finally hits its mark. A "man on the Moon" moment. She sees shimmers of reflected light flashing below her feet as the safety divers illuminate a digital depth gauge attached to the base structure. Its red lights blink 224 m. More than 70 m below the cruising depth of nuclear submarines! A nod, thumb, and forefinger touching okay and a smile to her safety divers, she reaches back over her shoulder and pulls a lanyard. A sudden rush of air is released as the cylinder tucked inside her wetsuit explodes compressed air into a lift-bag, transforming her from an aquatic mammal into a human missile headed for the surface. Her face is calm as she streaks to the surface, her face shrouded in a cloud of bubbles. Black slowly becomes dark blue and dark blue slowly becomes the lighter shades of the shallow water before, finally, the silhouette of the platform comes into view. Faster, faster, she approaches the light at the surface. Special sensors in her brain detect an acidic content in her blood from the build-up of carbon dioxide and signal to her lungs to expel it. It is this carbon dioxide, and not lack of oxygen, triggering her urge to breathe. How deep can you dive? 5 As she closes in on the surface, she feels an intensifying pressure inside her chest, almost like an inflating balloon. Breathe out! her body is telling her. Get rid of that carbon dioxide. Breathe outf 20 m. Hang on, she tells herself, marshaling all her will to fight the expanding sensation in her thoracic cavity. Don't panic. You've been here before. She can feel herself being pulled inexorably to the surface by the billowing lift-bag. The surface can't come soon enough. Her heart thumps and her ears ring loudly with its thumping as she begins to experience the insidious and painful sensations of hypoxia. Her extremities gradually begin to burn like the distant pain of a dentist's drill penetrating the anesthetic. Lactic acid, another by-product of hypoxia, elevates the pain to almost intolerable levels. She summons her concentration as her consciousness begins to shrink from lack of oxygen, her lungs screaming for her to break the surface as she struggles to overcome every human instinct to simply breathe. She concentrates on expelling air as she looks up, the shimmering undersides of the swells quickly becoming more distinct, their crests visible as thin bubbly streaks as she closes in on the surface. With the surface in sight, two freedivers join her for the final journey to the surface, kicking gracefully with their long fins. Like a sub aquatic projectile, the new No Limits world record-holder slices upward, pushing her head upright like a seal pushing its nose through a hole in the ice. Finally, the water lightens and she explodes onto the surface in a flurry of bubbles, her upper body shooting above the water before tumbling back down like a surfacing dolphin. The wind and waves and bright tropical sunlight slap suddenly against her face as she glances at her watch. It shows an elapsed time of 3 min and 29 sec. She senses the invigorating sound of the surface and gulps a lungful of air, another, and finally a thumbs-up and a smile. HOW DEEP CAN YOU DIVE? What you have just read is a fictional account of a female freediver performing a world record in the No Limits category (Panel!.l) - a mark currently held by Tanya Streeter (Figure 1.1), a Cayman Islands native who plunged to 160 m in 2002 (the male record is held by Austrian, Herbert Nitsch, who dived to 214 m in 2007). The depths to which Streeter and Nitsch descend were not thought humanly possible until very recently. As late as the 1960s, diving physiologists and doctors were convinced the immense water pressure below 100 m would crush the human chest cavity. After legendary freediver, Jacques Mayol, and other pioneers of the sport extended the human deep-diving envelope and descended below this depth, scientists were forced to re-evaluate their predictions and discovered that exposure to the pressures of deep water causes the body to respond in unexpected ways. The lungs contract to the size of an orange, the blood flowing to the extremities is re routed to the vital organs, and the heart rate slows to fewer than 10 beats per minute. This series of responses comprise the mammalian diving reflex (MDR), a metabolic switch recognized by researchers as a remnant of our aquatic origins. Since the late 1960s, scientists have studied, tested, and probed some of the best freedivers in the 6 No Limits Freediving Panel 1.1. No Limits freediving No Limits is one of the five freediving depth disciplines: I.

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