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Sanjay Gupta MD
Encore Presentation: A Look at Limits of Human Endurance
Aired December 26, 2004 - 08:30 ET
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
DR. SANJAY GUPTA, CNN MEDICAL CORRESPONDENT: Good morning and welcome to HOUSE CALL. Today we're going to show you people who push themselves to the limits of human endurance. Swimming in Antarctica, diving without tanks at depths you can't imagine and climbing the world's highest peak with no supplemental oxygen. Each of them living a life beyond limits.
(BEGIN VIDEO CLIP)
GUPTA (voice-over): This is a view most people only see from an airplane window. From the comfort and safety of a pressurized cabin. Ed Viesturs prefers the experience of high altitude in thin air. He's one of only a handful of people in the world to climb 26,000-foot peaks without the use of supplemental oxygen. How does he do it?
ED VIESTURS, HIGH ALTITUDE ADVENTURER: You have to have the desire or the thought that no matter what, this is the way I'm doing this.
GUPTA: Besides determination, there is something more.
VIESTURS: Genetically, I kind of, by freak of nature or whatever, got something within me that allows me to work well.
GUPTA: The average person his height has a 5 liter lung capacity. Viesturs' is 7. He excels at taking in large amounts of oxygen and uses it efficiently, much more than the average lowlander.
VIESTURS: Most people, at 50 percent of their maximum oxygen uptake, start working an aerobically, which isn't good. You can't do that for a long time. You get lactic acid and you would soon stop moving. Mine is like 88 percent of my yield to max. So I can go a lot longer, a lot further before I'm actually shifting to anaerobic.
GUPTA: At higher altitudes, the percentage of oxygen is the same, but the density is less. So it takes a lot more breathing to get the same amount of oxygen into your system. The higher you go, the higher the risk of developing altitude sickness, or much more dangerous, pulmonary or cerebral edema, excess water in the lung or brain. Both can be fatal. At extreme altitude, the so-called "death zone," a body actually begins to deteriorate. Clear thinking is often clouded and a single bad judgment could be your last. Viesturs knows when not to push too far.
VIESTURS: My goal is to be as safe as I can and to make sure that I get back here. (END VIDEOTAPE)
GUPTA: Ed Viesturs has climbed 13 of the 14 highest peaks without supplemental oxygen. Currently, He's in Nepal climbing Everest again and preparing trying to conquer that 14-peak, Annapurna.
Here to help us figure out how people, like Ed, can push themselves so far is Dr. Brownie Schoene. He's a professor of medicine at the University of California, San Diego, a pulmonary specialist and the president of the Wilderness Medicine Society as well. Which means he helps train doctors who then treat extreme athletes.
First of all, welcome Doctor. Thanks for spending some time with us.
DR. BROWNIE SCHOENE, UCSD MEDICAL CENTER: Good morning, my pleasure.
GUPTA: You are also a climber yourself. Give us some insight. How does a person like Ed, actually do what he does?
SCHOENE: Well, we've studied Ed, and a lot of people like ourselves over the years, going back to research expedition we had on Mt. Everest back in 1981, trying to answer that question. For years, it had been thought that Everest was too high to be climbed without oxygen supplementation, at least for humans. But what happens is the body adapts. And a body like Ed's, or great athletes like Ed, have different adaptations that optimize getting oxygen from the outside, where there's not much out there into the cells and allow them to function.
GUPTA: Yes. So for people watching, here's a question. Could anybody do it if they trained hard enough, do you think?
SCHOENE: No. They had to have chosen their parents well. Just like any elite athlete. I think that most people can adapt when they go to high altitude, whether it's skiing or trekking in Nepal. But not everybody can do what Ed does. He clearly has a very high aerobic capacity, in other words a big engine. And then he has some other characteristics of moving efficiently in the high altitude environment.
GUPTA: And we're going to talk about the combination of genetics and good training here, as we go throughout the show.
I want to share my own experience with you as well, Doctor. I went out to a lab in Colorado where they simulated taking me to just about 14,000 feet. Let's take a listen to what happened.
(BEGIN VIDEO CLIP)
GUPTA (on camera): I feel a little bit light headed now. I mean things are spinning a little bit more around me.
UNIDENTIFIED MALE: OK. GUPTA: I'm not seeing spots or anything.
UNIDENTIFIED MALE: Sure.
GUPTA: Having a little bit. I was trying to ask you another question, but I forgot what the question was I was before I was going to ask you.
(END VIDEO CLIP)
GUPTA: So, as you can see there, Dr. Schoene, I was beginning to feel a little impaired there. Question is this. How do climbers, like Ed, know that their decision making up at that altitude may be getting a little iffy?
SCHOENE: Well, sometimes they don't. And that's really one of the critical things that happens at extreme altitude. And there are many, many stories of climbers who clearly have lost judgment, have lost the ability to figure out how to go down. And what you experienced at 14,000 feet because you were exposed there quickly, your body didn't have time to adapt. And that is at sort of the limit when you go up to 28, 29,000 for adaptation and proper thinking.
GUPTA: You know, and that's a good point. Because I did go up quickly in that lab with no time to acclimate, which can make you sick. Made me a little bit sick.
Some tips to help you prevent altitude sickness, whether it's skiing, hiking or climbing a mountain. Ascend slowly and limit physical activity. And remember to rest frequently. Plus, if you're going to spend the night, try and sleep at lower altitudes. That's where you've been during the day and that gives your body a chance to recover.
Dr. Schoene, do you have a chance of how long does it take a normal person to acclimate to these sorts of high altitudes?
SCHOENE: Well, everybody is a little bit different and that's an important fact. If you're with a group of people, some will adapt more quickly than others. And for people who go to ski at 9 to 10,000 feet or go trekking in Nepal to 13 and 14,000, they really should allow a number of days to acclimatize.
For instance, in Colorado, it probably takes three to four days for people to begin to feel pretty good so they can physically perform. In Nepal, for instance, or in South America, you should probably take a week or two or more. Now, somebody like Ed going to 20, 26, 28,000, we're talking weeks and sometimes a couple of months.
GUPTA: It's really remarkable. And we're going to hear a lot more about this. To hear more about Ed's amazing climbs, make sure to tune into the CNN special, "LIFE BEYOND LIMITS." That's on Sunday night at 9:00 p.m.
But first, more HOUSE CALL.
(BEGIN VIDEO CLIP)
LYNNE COX, ENDURANCE SWIMMER: It was so far beyond what I ever thought was possible. It was really out there.
UNIDENTIFIED FEMALE (voice-over): Swimming in the frigid waters of Antarctica. The amazing story is just ahead.
Plus...
TANYA STREETER, FREEDIVER: I can feel the pressure quite a lot on my chest. The lungs reach residual volume, which means that they collapse to as small as they're going to collapse to. Which is kind of like a shrunken grapefruit or something.
UNIDENTIFIED FEMALE: We'll show you how this woman dives farther are than just about anyone.
But first, take the "Daily Dose" quiz. How long can a normal person survive in below freezing water? The answer when we come back. (END VIDEO CLIP)
(COMMERCIAL BREAK)
UNIDENTIFIED FEMALE: Checking the "Daily Dose" quiz. We asked, how long can a normal person survive in below freezing water? The answer, under 15 minutes. At that point, most people start to go unconscious.
GUPTA: Swimming in near freezing water is something most people would avoid. But you are about to meet an amazing person. She's an author and an extreme swimmer who has covered nearly a mile and a quarter in Antarctica. Yes, dodging icebergs along the way.
(BEGIN VIDEO CLIP)
GUPTA: In these majestic surroundings, Lynne Cox went beyond the known limits of the human body. Water simply doesn't get any colder.
COX: You feel an intense cold, extreme cold. And you know, in that first moment when you hit the water, your body is changing in a huge way.
GUPTA: First, of course, we shiver. After that, the body responds to cold by shunting blood away from the extremities to focus on warming the heart, lungs and brain. But in water this cold, most people would die in a matter of minutes as their muscles, including the heart, seize up.
Cox is different. Her body actually gets warmer as she swims. Cox, who once set the speed record for crossing the English Channel, is physically gifted. But she also has something else, an ability to focus on the challenge, not the cold.
COX: Well, the swim itself was extremely beautiful and harsh. I mean everything is sort of reduced to the colors of blues and whites and greens. I mean greens of the waters, but also the harshness of it; that knowing if you stay in the water a moment too long, you can go into cardiac arrest. There's a knowledge that you are really on the edge here and that you can push yourself too far.
(END VIDEOTAPE)
GUPTA: As Lynne pointed out, you have to know your own personal limits. Which is why we want to warn you not to try any of these sports on your own. An important point.
Let's bring out Dr. Brownie Schoene. He's in San Diego. He's a pulmonary specialist who works with extreme athletes.
And you've worked with Lynne Cox, who we just profiled as well. Is it genetics, is it training or is it sheer willpower that allows her to do what she does?
SCHOENE: Well, it's a little of all three. As you know, Lynne has been swimming since she was very young. First of all, she is a great, great swimmer. And when she was if her teens she then went to swim some distances. Of course, the English Channel and so forth. And so she has the capability to do that. Secondly, will power is incredibly important. And in addition to that, in the cold water that she swims, her physiology just allows her, unlike most people, to be able to survive and actually even thrive.
GUPTA: Really remarkable; I mean just getting into the water in the first place, I think most people would be out at that point.
We sent our cameras to get questions on this topic. Let's take a listen.
(BEGIN VIDEO CLIP)
UNIDENTIFIED MALE: What kind of effect does it have on your skin? Your facial skin or do you have to cover up your entire body. I mean how do you go out in temperatures -- I don't even know what the water temperature would be. And how does that not kill you?
(END VIDEO CLIP)
GUPTA: So a couple of questions in there. First of all, Lynne was not wearing a wet suit. and she did have some nerve damage to her hands and feet because of the cold. However, six months after the swim she recovered fully from the nerve damage.
Doctor, what other sorts of traits does Lynne have that makes her unique and keep it from killing her, quite literally?
SCHOENE: Well, I think one of the important things in that type of cold-water swimming is to maintain your core temperature. And by that, I mean your main body temperature so that just as in any cold environment, the body decides to compromise or sacrifice some things. And the reason she may have gotten some cold injury to her skin is that the environment was so cold, she lost a lot of heat peripherally and the blood flow to the skin constricts. And then making the skin susceptible and the small nerves susceptible to damage. But she does it very, very well and very efficiently, unlike most of us. I certainly wouldn't go in that water.
GUPTA: Really, really interesting. But worth pointing out that water was near freezing, 32 to 34 degrees.
When House CALL continues, ignoring your basic instinct to breathe. Why would you do it? Stay tuned.
(BEGIN VIDEO CLIP)
UNIDENTIFIED MALE: Your brain is receiving a lot of signals from your body that says this is not normal.
UNIDENTIFIED FEMALE: Holding your breath and diving until you can't see. We'll show you the breathtaking pictures.
And...
TODD ROBBINS, SIDESHOW MASTER: Tilt your head back and stick your tongue out. And I'm going to do something here. OK? Very simply, did that hurt?
GUPTA (on camera): No.
UNIDENTIFIED FEMALE: We'll show you how they do those carnival tricks a bit later.
First, here's a tip from our health conscious "Bod Squad."
GUPTA (voice-over): Not ready to take on Mt. Everest? Well, you can still satisfy your need to go vertical on this playground of ropes, rocks and high walls. Flashback to the days of slides and monkey bars with indoor rock climbing. And while you're busy having fun, you'll be challenging your mind and your body in new ways. All of that while getting a great workout. You're going to use all your major muscle groups in this activity and build your strength and flexibility.
The movement is similar to climbing stairs or making your way up a steep hill but with finesse and precision. And don't worry; you don't have to be related to Spider-Man. Just add in the skills you used on the monkey bars when you were a kid and voila! You are climbing. Be sure to work with a reputable instructor, follow basic rules of safety, and get clearance from your doctor.
(END VIDEO CLIP)
(COMMERCIAL BREAK)
GUPTA: Welcome back. You may not have heard of free diving. It's a sport where you hold your breath and you see how deep you can dive. The concept dates back more than 2,000 years to Japanese pearl diving. But now it's considered an extreme sport.
(BEGIN VIDEOTAPE)
GUPTA (voice-over): Here's Tonya Streeter getting ready to break a world free diving record. The native Cayman Islander has trained for years but now relies on human physiology to help her.
STREETER: I get in the water and I begin a series of facial immersion. Basically subjects the face, the nerve endings and receptors around the eyes and mouth to the cool water on the face, which helps to trigger the dive reflex, which is the heart rate slowing down.
GUPTA: A slower heartbeat means less blood flowing and less oxygen needed for that blood. That allows Streeter to push her body to new limits. By slowing down the heart, the dive reflex allows mammals, like whales and seals to spend a half an hour or more below water. To see the record, Streeter needs to hold her breath for more than three minutes. That will give her enough time to ride a weighted sled down 160 meters, 525 feet and then return to the surface. Her trip down is like riding an elevator from the top of a 50-story building to the ground floor.
STREETER: Anything after 400 feet, especially somewhere where, even Turks and the Caicos Islands where we set these records and the water clarity is phenomenal; it's still pitch black after 400 feet. So I let go of the lift bag around 100 feet or so, and swim the rest of the way up.
(APPLAUSE)
(CHEERING)
GUPTA: Incredible pictures. We're talking about living a life beyond limits. Athletes who push themselves to the extremes. Dr. Brownie Schoene works with these athletes as a pulmonary specialist.
Doctor, how is it, you know, just on a practical note. How is it that Tonya Streeter can go that deep and come back up without getting the bends?
SCHOENE: You know, when one gets the bends, it's the nitrogen in the air that pushed in by the high pressure into the blood. And that's what happened with scuba divers if they ascend too quickly because that nitrogen comes back out. In the free diving, because nitrogen is not very soluble, that short period -- relatively short period of time doesn't afford enough time for the nitrogen to get into the blood. So, that's why the free divers can get away without getting the bends.
GUPTA: So the single breath, in this case, may be a little protective against the bends.
Let's just paint a picture of what Tanya is going through as she dives. It's very interesting. While free diving the various things happen. Eardrums can collapse if she doesn't equalize the pressure. Vision becomes blurred and your legs can go numb. In addition, Tonya's heart rate drops and her lungs shrink to the size of a shrunken grapefruit.
Very interesting questions coming in on this, Doctor. We've got another question now in Atlanta from our roving camera. (BEGIN VIDEO CLIP)
UNIDENTIFIED FEMALE: What are her strategies and techniques to allow her to be able to stay under water for 6 1/2 minutes?
(END VIDEO CLIP)
GUPTA: Interesting question there, Dr. Schoene. What do you think?
SCHOENE: Well, I think that, first of all, it takes a lot of physical and mental training. She has to relax totally going down because any exercise would increase her metabolism, would increase her carbon dioxide production, her drive to breathe, which is very, very strong. So she has to relax. Secondly, there will be an intense drive to breath, which she needs mentally to overcome and try to suppress obviously. So she's done a lot of training, both physical and mental training to achieve these remarkable feats.
GUPTA: Dr. Brownie Schoene, thank you so much for sharing your expertise with us this morning. I think we all got a lot out of it.
SCHOENE: You're welcome. It was great fun.
GUPTA: It was great fun for us as well.
OK. We're not done yet at home there, folks. When we come back, we're going to bring you some of this week's top medical news. Stay with us.
UNIDENTIFIED FEMALE: Coming up on HOUSE CALL, what did your mother tell you about playing with fire?
(BEGIN VIDEO CLIP)
BRIAN BRUSHWOOD, SIDESHOW MASTER: If you get it right it's like a fireball.
GUPTA (on camera): That's awesome.
(END VIDEO CLIP)
UNIDENTIFIED FEMALE: More, "How Did They Do That?" after the break. Stay tuned.
(COMMERCIAL BREAK)
GUPTA: Welcome back to HOUSE CALL. Let's take a look now at some of this week's top medical headlines in today's edition of "The Pulse."
UNIDENTIFIED FEMALE: Sixteen percent of America's children are overweight. Now a new study in the "Journal of the American Medical Association" says they may be facing a hidden danger, high blood pressure. And for a child, high blood pressure significantly increases the risk of kidney disease, heart disease or stroke as an adult.
Seniors on Medicare can now apply for a prescription drug discount card. To find which of the 73 cards will save you the most money, call 1-800-medicare or log on to www.medicare.gov.
GUPTA: Welcome back. We're about to introduce you to a sideshow master, a man who does stunts that look too impossible to be real. He warned us many times do not try this at home. But with his guidance, even I learned a few tricks.
(BEGIN VIDEOTAPE)
ROBBINS: I want to show you a little something about fire.
GUPTA (voice-over): How did I get myself into this? We're backstage with Todd Robbins, a sideshow master who does a lot of things you shouldn't do from swallowing swords to blowing fireballs.
ROBBINS: What I want you to do is just tilt our head back and stick your tongue out and I'm going to do something here. OK. Very simply. Did that hurt?
GUPTA: Amazing to me, it didn't hurt a bit. As Todd says, it's all about physics and anatomy.
ROBBINS: And the fact is there was a little fire that actually was retained on your tongue for a second there. But it didn't hurt because of the moisture on the tongue.
OK? You ready? Let me get a little fuel on this thing and don't breathe in. You take this one. Here we go. Lick up the lips. All right. And if you would, yes, opa -- tilt the head back. open the mouth. Hold your breath. Take a deep breath in. Hold it! Put it in! Close the mouth! OK.
GUPTA (on camera): Wow.
(LAUGHTER)
ROBBINS: There you go. Are you all right? There you go. You just ate fire.
GUPTA: That was incredible. Did it look pretty cool?
ROBBINS: Yes, I think it looked pretty cool.
(LAUGHTER)
GUPTA (voice-over): With that lesson under my belt, I headed to Texas to meet with another master, Brian Brushwood, who literally wrote the book on eating fire. At first glance, Brian seems like a normal doting father. Penelope Ray was just 7 days old when we met her.
BRUSHWOOD: Hey, baby.
GUPTA: But how many dads can do this?
BRUSHWOOD: If you get it right, it looks like a little fireball jumping up there.
GUPTA (on camera): That's awesome. That's awesome.
(voice-over): Today, he's working on something called the Human Candle.
BRUSHWOOD: In fact, practice with me real quick right now. Practice just -- just -- just get a mouthful of air and let it out as slowly as you can. And you can totally impress all the fire-eating people because they think this is one of the hardest things to do.
Good, wide open tongue out. There you go. Bring it in, you're showing your teeth.
GUPTA: It's hot.
BRUSHWOOD: Yes, it is hot.
GUPTA: I burnt my upper lip.
BRUSHWOOD: Then you need to tilt back. If you're getting the upper lip -- there you go. In there, hold it. pull it out. I think you're just exhaling is what's going on. All the way in. There you go. Yes! Did you feel that?
GUPTA: Yes.
BRUSHWOOD: You can tell when it's in there.
All the way in, hold it. Hold it there. Hold it there. You've got plenty. Lift slowly. Yes! That was cool!
(END VIDEOTAPE)
GUPTA: There you have it.
We're out of time for today. Make sure to watch next weekend. We're looking at some of the best questions we never had time to answer from heart disease to headaches. That's next weekend on HOUSE CALL. Don't miss it. I'm Dr. Sanjay Gupta. Stay tuned now for more news on CNN.
TO ORDER A VIDEO OF THIS TRANSCRIPT, PLEASE CALL 800-CNN-NEWS OR USE OUR SECURE ONLINE ORDER FORM LOCATED AT www.fdch.com
Aired December 26, 2004 - 08:30 ET
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
DR. SANJAY GUPTA, CNN MEDICAL CORRESPONDENT: Good morning and welcome to HOUSE CALL. Today we're going to show you people who push themselves to the limits of human endurance. Swimming in Antarctica, diving without tanks at depths you can't imagine and climbing the world's highest peak with no supplemental oxygen. Each of them living a life beyond limits.
(BEGIN VIDEO CLIP)
GUPTA (voice-over): This is a view most people only see from an airplane window. From the comfort and safety of a pressurized cabin. Ed Viesturs prefers the experience of high altitude in thin air. He's one of only a handful of people in the world to climb 26,000-foot peaks without the use of supplemental oxygen. How does he do it?
ED VIESTURS, HIGH ALTITUDE ADVENTURER: You have to have the desire or the thought that no matter what, this is the way I'm doing this.
GUPTA: Besides determination, there is something more.
VIESTURS: Genetically, I kind of, by freak of nature or whatever, got something within me that allows me to work well.
GUPTA: The average person his height has a 5 liter lung capacity. Viesturs' is 7. He excels at taking in large amounts of oxygen and uses it efficiently, much more than the average lowlander.
VIESTURS: Most people, at 50 percent of their maximum oxygen uptake, start working an aerobically, which isn't good. You can't do that for a long time. You get lactic acid and you would soon stop moving. Mine is like 88 percent of my yield to max. So I can go a lot longer, a lot further before I'm actually shifting to anaerobic.
GUPTA: At higher altitudes, the percentage of oxygen is the same, but the density is less. So it takes a lot more breathing to get the same amount of oxygen into your system. The higher you go, the higher the risk of developing altitude sickness, or much more dangerous, pulmonary or cerebral edema, excess water in the lung or brain. Both can be fatal. At extreme altitude, the so-called "death zone," a body actually begins to deteriorate. Clear thinking is often clouded and a single bad judgment could be your last. Viesturs knows when not to push too far.
VIESTURS: My goal is to be as safe as I can and to make sure that I get back here. (END VIDEOTAPE)
GUPTA: Ed Viesturs has climbed 13 of the 14 highest peaks without supplemental oxygen. Currently, He's in Nepal climbing Everest again and preparing trying to conquer that 14-peak, Annapurna.
Here to help us figure out how people, like Ed, can push themselves so far is Dr. Brownie Schoene. He's a professor of medicine at the University of California, San Diego, a pulmonary specialist and the president of the Wilderness Medicine Society as well. Which means he helps train doctors who then treat extreme athletes.
First of all, welcome Doctor. Thanks for spending some time with us.
DR. BROWNIE SCHOENE, UCSD MEDICAL CENTER: Good morning, my pleasure.
GUPTA: You are also a climber yourself. Give us some insight. How does a person like Ed, actually do what he does?
SCHOENE: Well, we've studied Ed, and a lot of people like ourselves over the years, going back to research expedition we had on Mt. Everest back in 1981, trying to answer that question. For years, it had been thought that Everest was too high to be climbed without oxygen supplementation, at least for humans. But what happens is the body adapts. And a body like Ed's, or great athletes like Ed, have different adaptations that optimize getting oxygen from the outside, where there's not much out there into the cells and allow them to function.
GUPTA: Yes. So for people watching, here's a question. Could anybody do it if they trained hard enough, do you think?
SCHOENE: No. They had to have chosen their parents well. Just like any elite athlete. I think that most people can adapt when they go to high altitude, whether it's skiing or trekking in Nepal. But not everybody can do what Ed does. He clearly has a very high aerobic capacity, in other words a big engine. And then he has some other characteristics of moving efficiently in the high altitude environment.
GUPTA: And we're going to talk about the combination of genetics and good training here, as we go throughout the show.
I want to share my own experience with you as well, Doctor. I went out to a lab in Colorado where they simulated taking me to just about 14,000 feet. Let's take a listen to what happened.
(BEGIN VIDEO CLIP)
GUPTA (on camera): I feel a little bit light headed now. I mean things are spinning a little bit more around me.
UNIDENTIFIED MALE: OK. GUPTA: I'm not seeing spots or anything.
UNIDENTIFIED MALE: Sure.
GUPTA: Having a little bit. I was trying to ask you another question, but I forgot what the question was I was before I was going to ask you.
(END VIDEO CLIP)
GUPTA: So, as you can see there, Dr. Schoene, I was beginning to feel a little impaired there. Question is this. How do climbers, like Ed, know that their decision making up at that altitude may be getting a little iffy?
SCHOENE: Well, sometimes they don't. And that's really one of the critical things that happens at extreme altitude. And there are many, many stories of climbers who clearly have lost judgment, have lost the ability to figure out how to go down. And what you experienced at 14,000 feet because you were exposed there quickly, your body didn't have time to adapt. And that is at sort of the limit when you go up to 28, 29,000 for adaptation and proper thinking.
GUPTA: You know, and that's a good point. Because I did go up quickly in that lab with no time to acclimate, which can make you sick. Made me a little bit sick.
Some tips to help you prevent altitude sickness, whether it's skiing, hiking or climbing a mountain. Ascend slowly and limit physical activity. And remember to rest frequently. Plus, if you're going to spend the night, try and sleep at lower altitudes. That's where you've been during the day and that gives your body a chance to recover.
Dr. Schoene, do you have a chance of how long does it take a normal person to acclimate to these sorts of high altitudes?
SCHOENE: Well, everybody is a little bit different and that's an important fact. If you're with a group of people, some will adapt more quickly than others. And for people who go to ski at 9 to 10,000 feet or go trekking in Nepal to 13 and 14,000, they really should allow a number of days to acclimatize.
For instance, in Colorado, it probably takes three to four days for people to begin to feel pretty good so they can physically perform. In Nepal, for instance, or in South America, you should probably take a week or two or more. Now, somebody like Ed going to 20, 26, 28,000, we're talking weeks and sometimes a couple of months.
GUPTA: It's really remarkable. And we're going to hear a lot more about this. To hear more about Ed's amazing climbs, make sure to tune into the CNN special, "LIFE BEYOND LIMITS." That's on Sunday night at 9:00 p.m.
But first, more HOUSE CALL.
(BEGIN VIDEO CLIP)
LYNNE COX, ENDURANCE SWIMMER: It was so far beyond what I ever thought was possible. It was really out there.
UNIDENTIFIED FEMALE (voice-over): Swimming in the frigid waters of Antarctica. The amazing story is just ahead.
Plus...
TANYA STREETER, FREEDIVER: I can feel the pressure quite a lot on my chest. The lungs reach residual volume, which means that they collapse to as small as they're going to collapse to. Which is kind of like a shrunken grapefruit or something.
UNIDENTIFIED FEMALE: We'll show you how this woman dives farther are than just about anyone.
But first, take the "Daily Dose" quiz. How long can a normal person survive in below freezing water? The answer when we come back. (END VIDEO CLIP)
(COMMERCIAL BREAK)
UNIDENTIFIED FEMALE: Checking the "Daily Dose" quiz. We asked, how long can a normal person survive in below freezing water? The answer, under 15 minutes. At that point, most people start to go unconscious.
GUPTA: Swimming in near freezing water is something most people would avoid. But you are about to meet an amazing person. She's an author and an extreme swimmer who has covered nearly a mile and a quarter in Antarctica. Yes, dodging icebergs along the way.
(BEGIN VIDEO CLIP)
GUPTA: In these majestic surroundings, Lynne Cox went beyond the known limits of the human body. Water simply doesn't get any colder.
COX: You feel an intense cold, extreme cold. And you know, in that first moment when you hit the water, your body is changing in a huge way.
GUPTA: First, of course, we shiver. After that, the body responds to cold by shunting blood away from the extremities to focus on warming the heart, lungs and brain. But in water this cold, most people would die in a matter of minutes as their muscles, including the heart, seize up.
Cox is different. Her body actually gets warmer as she swims. Cox, who once set the speed record for crossing the English Channel, is physically gifted. But she also has something else, an ability to focus on the challenge, not the cold.
COX: Well, the swim itself was extremely beautiful and harsh. I mean everything is sort of reduced to the colors of blues and whites and greens. I mean greens of the waters, but also the harshness of it; that knowing if you stay in the water a moment too long, you can go into cardiac arrest. There's a knowledge that you are really on the edge here and that you can push yourself too far.
(END VIDEOTAPE)
GUPTA: As Lynne pointed out, you have to know your own personal limits. Which is why we want to warn you not to try any of these sports on your own. An important point.
Let's bring out Dr. Brownie Schoene. He's in San Diego. He's a pulmonary specialist who works with extreme athletes.
And you've worked with Lynne Cox, who we just profiled as well. Is it genetics, is it training or is it sheer willpower that allows her to do what she does?
SCHOENE: Well, it's a little of all three. As you know, Lynne has been swimming since she was very young. First of all, she is a great, great swimmer. And when she was if her teens she then went to swim some distances. Of course, the English Channel and so forth. And so she has the capability to do that. Secondly, will power is incredibly important. And in addition to that, in the cold water that she swims, her physiology just allows her, unlike most people, to be able to survive and actually even thrive.
GUPTA: Really remarkable; I mean just getting into the water in the first place, I think most people would be out at that point.
We sent our cameras to get questions on this topic. Let's take a listen.
(BEGIN VIDEO CLIP)
UNIDENTIFIED MALE: What kind of effect does it have on your skin? Your facial skin or do you have to cover up your entire body. I mean how do you go out in temperatures -- I don't even know what the water temperature would be. And how does that not kill you?
(END VIDEO CLIP)
GUPTA: So a couple of questions in there. First of all, Lynne was not wearing a wet suit. and she did have some nerve damage to her hands and feet because of the cold. However, six months after the swim she recovered fully from the nerve damage.
Doctor, what other sorts of traits does Lynne have that makes her unique and keep it from killing her, quite literally?
SCHOENE: Well, I think one of the important things in that type of cold-water swimming is to maintain your core temperature. And by that, I mean your main body temperature so that just as in any cold environment, the body decides to compromise or sacrifice some things. And the reason she may have gotten some cold injury to her skin is that the environment was so cold, she lost a lot of heat peripherally and the blood flow to the skin constricts. And then making the skin susceptible and the small nerves susceptible to damage. But she does it very, very well and very efficiently, unlike most of us. I certainly wouldn't go in that water.
GUPTA: Really, really interesting. But worth pointing out that water was near freezing, 32 to 34 degrees.
When House CALL continues, ignoring your basic instinct to breathe. Why would you do it? Stay tuned.
(BEGIN VIDEO CLIP)
UNIDENTIFIED MALE: Your brain is receiving a lot of signals from your body that says this is not normal.
UNIDENTIFIED FEMALE: Holding your breath and diving until you can't see. We'll show you the breathtaking pictures.
And...
TODD ROBBINS, SIDESHOW MASTER: Tilt your head back and stick your tongue out. And I'm going to do something here. OK? Very simply, did that hurt?
GUPTA (on camera): No.
UNIDENTIFIED FEMALE: We'll show you how they do those carnival tricks a bit later.
First, here's a tip from our health conscious "Bod Squad."
GUPTA (voice-over): Not ready to take on Mt. Everest? Well, you can still satisfy your need to go vertical on this playground of ropes, rocks and high walls. Flashback to the days of slides and monkey bars with indoor rock climbing. And while you're busy having fun, you'll be challenging your mind and your body in new ways. All of that while getting a great workout. You're going to use all your major muscle groups in this activity and build your strength and flexibility.
The movement is similar to climbing stairs or making your way up a steep hill but with finesse and precision. And don't worry; you don't have to be related to Spider-Man. Just add in the skills you used on the monkey bars when you were a kid and voila! You are climbing. Be sure to work with a reputable instructor, follow basic rules of safety, and get clearance from your doctor.
(END VIDEO CLIP)
(COMMERCIAL BREAK)
GUPTA: Welcome back. You may not have heard of free diving. It's a sport where you hold your breath and you see how deep you can dive. The concept dates back more than 2,000 years to Japanese pearl diving. But now it's considered an extreme sport.
(BEGIN VIDEOTAPE)
GUPTA (voice-over): Here's Tonya Streeter getting ready to break a world free diving record. The native Cayman Islander has trained for years but now relies on human physiology to help her.
STREETER: I get in the water and I begin a series of facial immersion. Basically subjects the face, the nerve endings and receptors around the eyes and mouth to the cool water on the face, which helps to trigger the dive reflex, which is the heart rate slowing down.
GUPTA: A slower heartbeat means less blood flowing and less oxygen needed for that blood. That allows Streeter to push her body to new limits. By slowing down the heart, the dive reflex allows mammals, like whales and seals to spend a half an hour or more below water. To see the record, Streeter needs to hold her breath for more than three minutes. That will give her enough time to ride a weighted sled down 160 meters, 525 feet and then return to the surface. Her trip down is like riding an elevator from the top of a 50-story building to the ground floor.
STREETER: Anything after 400 feet, especially somewhere where, even Turks and the Caicos Islands where we set these records and the water clarity is phenomenal; it's still pitch black after 400 feet. So I let go of the lift bag around 100 feet or so, and swim the rest of the way up.
(APPLAUSE)
(CHEERING)
GUPTA: Incredible pictures. We're talking about living a life beyond limits. Athletes who push themselves to the extremes. Dr. Brownie Schoene works with these athletes as a pulmonary specialist.
Doctor, how is it, you know, just on a practical note. How is it that Tonya Streeter can go that deep and come back up without getting the bends?
SCHOENE: You know, when one gets the bends, it's the nitrogen in the air that pushed in by the high pressure into the blood. And that's what happened with scuba divers if they ascend too quickly because that nitrogen comes back out. In the free diving, because nitrogen is not very soluble, that short period -- relatively short period of time doesn't afford enough time for the nitrogen to get into the blood. So, that's why the free divers can get away without getting the bends.
GUPTA: So the single breath, in this case, may be a little protective against the bends.
Let's just paint a picture of what Tanya is going through as she dives. It's very interesting. While free diving the various things happen. Eardrums can collapse if she doesn't equalize the pressure. Vision becomes blurred and your legs can go numb. In addition, Tonya's heart rate drops and her lungs shrink to the size of a shrunken grapefruit.
Very interesting questions coming in on this, Doctor. We've got another question now in Atlanta from our roving camera. (BEGIN VIDEO CLIP)
UNIDENTIFIED FEMALE: What are her strategies and techniques to allow her to be able to stay under water for 6 1/2 minutes?
(END VIDEO CLIP)
GUPTA: Interesting question there, Dr. Schoene. What do you think?
SCHOENE: Well, I think that, first of all, it takes a lot of physical and mental training. She has to relax totally going down because any exercise would increase her metabolism, would increase her carbon dioxide production, her drive to breathe, which is very, very strong. So she has to relax. Secondly, there will be an intense drive to breath, which she needs mentally to overcome and try to suppress obviously. So she's done a lot of training, both physical and mental training to achieve these remarkable feats.
GUPTA: Dr. Brownie Schoene, thank you so much for sharing your expertise with us this morning. I think we all got a lot out of it.
SCHOENE: You're welcome. It was great fun.
GUPTA: It was great fun for us as well.
OK. We're not done yet at home there, folks. When we come back, we're going to bring you some of this week's top medical news. Stay with us.
UNIDENTIFIED FEMALE: Coming up on HOUSE CALL, what did your mother tell you about playing with fire?
(BEGIN VIDEO CLIP)
BRIAN BRUSHWOOD, SIDESHOW MASTER: If you get it right it's like a fireball.
GUPTA (on camera): That's awesome.
(END VIDEO CLIP)
UNIDENTIFIED FEMALE: More, "How Did They Do That?" after the break. Stay tuned.
(COMMERCIAL BREAK)
GUPTA: Welcome back to HOUSE CALL. Let's take a look now at some of this week's top medical headlines in today's edition of "The Pulse."
UNIDENTIFIED FEMALE: Sixteen percent of America's children are overweight. Now a new study in the "Journal of the American Medical Association" says they may be facing a hidden danger, high blood pressure. And for a child, high blood pressure significantly increases the risk of kidney disease, heart disease or stroke as an adult.
Seniors on Medicare can now apply for a prescription drug discount card. To find which of the 73 cards will save you the most money, call 1-800-medicare or log on to www.medicare.gov.
GUPTA: Welcome back. We're about to introduce you to a sideshow master, a man who does stunts that look too impossible to be real. He warned us many times do not try this at home. But with his guidance, even I learned a few tricks.
(BEGIN VIDEOTAPE)
ROBBINS: I want to show you a little something about fire.
GUPTA (voice-over): How did I get myself into this? We're backstage with Todd Robbins, a sideshow master who does a lot of things you shouldn't do from swallowing swords to blowing fireballs.
ROBBINS: What I want you to do is just tilt our head back and stick your tongue out and I'm going to do something here. OK. Very simply. Did that hurt?
GUPTA: Amazing to me, it didn't hurt a bit. As Todd says, it's all about physics and anatomy.
ROBBINS: And the fact is there was a little fire that actually was retained on your tongue for a second there. But it didn't hurt because of the moisture on the tongue.
OK? You ready? Let me get a little fuel on this thing and don't breathe in. You take this one. Here we go. Lick up the lips. All right. And if you would, yes, opa -- tilt the head back. open the mouth. Hold your breath. Take a deep breath in. Hold it! Put it in! Close the mouth! OK.
GUPTA (on camera): Wow.
(LAUGHTER)
ROBBINS: There you go. Are you all right? There you go. You just ate fire.
GUPTA: That was incredible. Did it look pretty cool?
ROBBINS: Yes, I think it looked pretty cool.
(LAUGHTER)
GUPTA (voice-over): With that lesson under my belt, I headed to Texas to meet with another master, Brian Brushwood, who literally wrote the book on eating fire. At first glance, Brian seems like a normal doting father. Penelope Ray was just 7 days old when we met her.
BRUSHWOOD: Hey, baby.
GUPTA: But how many dads can do this?
BRUSHWOOD: If you get it right, it looks like a little fireball jumping up there.
GUPTA (on camera): That's awesome. That's awesome.
(voice-over): Today, he's working on something called the Human Candle.
BRUSHWOOD: In fact, practice with me real quick right now. Practice just -- just -- just get a mouthful of air and let it out as slowly as you can. And you can totally impress all the fire-eating people because they think this is one of the hardest things to do.
Good, wide open tongue out. There you go. Bring it in, you're showing your teeth.
GUPTA: It's hot.
BRUSHWOOD: Yes, it is hot.
GUPTA: I burnt my upper lip.
BRUSHWOOD: Then you need to tilt back. If you're getting the upper lip -- there you go. In there, hold it. pull it out. I think you're just exhaling is what's going on. All the way in. There you go. Yes! Did you feel that?
GUPTA: Yes.
BRUSHWOOD: You can tell when it's in there.
All the way in, hold it. Hold it there. Hold it there. You've got plenty. Lift slowly. Yes! That was cool!
(END VIDEOTAPE)
GUPTA: There you have it.
We're out of time for today. Make sure to watch next weekend. We're looking at some of the best questions we never had time to answer from heart disease to headaches. That's next weekend on HOUSE CALL. Don't miss it. I'm Dr. Sanjay Gupta. Stay tuned now for more news on CNN.
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