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FAT SLOBS IN SPACE
Jonathan Vos Post
28 March 1991 (c) 1991 by Emerald City Publishing
LOAD UP FOR LIFT OFFAre you overweight? Out of shape? Afraid that you'll be rejected for spaceflight when your chance finally comes? Worry no more -- space biologists have good news for you! First, the bad news. As William J. Broad puts it (New York Times, 26 March 1991, p.B5): "While logging more than 50,000 hours in space over three decades, American astronauts have suffered nausea, anemia, lethargy, loss of appetite, headaches, disorientation, motion sickness, heart palpitations, fatigue, depression, weakened defenses against infectious disease and a loss of blood volume, muscle mass, and bone." The Japanese TV reporter on Mir felt just awful, and so did Senator Jake Garn. This would discourage some people, but not you. You want to get into space no matter what, right? We all know that astronauts are super-healthy types who love to get up before dawn to run a few miles. So if they get sick, we'd be in for an even worse time. Seems logical. But it just ain't so. First of all, being seriously overweight might just be the best way to avoid the motion sickness that plagues a third of astronauts in orbit.
Head Over Heels in the DarkMotion sickness tests here on Earth involve strapping you into a simulator and spinning you head-over-heels in total darkness. For years, scientists such as Carolyn L. Huntoon, director of the space sciences directorate at the NASA Johnson Space Center, have experimented with drugs, hypnosis, biofeedback, and anything else that might cut down on what they delicately call "stomach awareness." Drugs that work on Earth didn't work in orbit. That's because oral medications are absorbed differently in space, so these drugs are now given to astronauts by injection. If you are seriously overweight, however, you don't need drugs or anything else. Dr. Bob S. K. Cheung, an expert on biological adaptation to weightlessness, works at the Canadian Defense and Civil Institute of Environmental Medicine in Toronto. He has been involved in the head-over- heels testing. As William J. Broad reports, Dr. Cheung concludes that "if you are grossly obese, we cannot get you sick." Lying in Bed All DayOne cheap and easy way to simulate the biological effect of weightlesness is to lie in bed for over a week. If you are overweight and out of shape, that probably sounds like a pretty comfortable way to practice for spaceflight. As John H. Greenleaf of NASA Ames Research Center reports ("Physiology of Prolonged Bed Rest", see also NASA Tech Briefs, March 1991, p.68) the body tends to decondition significantly under such treatment. Although doctors have, for centuries, prescribed bed rest for a day or more to patients with injury or disease, this deconditioning goes on at the same time as healing. Every system in the body is affected, due to decreased blood pressure, decreased longitudinal pressure on long bones, slight reduction in total-body metabolism, dietary changes, and perhaps the psychology of just lying in bed all day. The result is immediate disturbance of fluid electrolytes, and then, within the first week, noticeable atrophy of muscle tissue. As your muscles begin to waste away, more nitrogen appears in your urine. You begin to lose weight, but it is muscle, not fat, that's disappearing. After two weeks, your bone density declines as significant amount of calcium are lost through the urine. These effects are very similar to what happens to astronauts in orbit. But how can this be good news for you? As Danielle J. Goldwater, of NASA Ames Research Center, describes ("Factors Related to +Gz Acceleration Performance in Aerobically Trained and Sedentary Men After Shuttle Microgravity Simulation", see also NASA Tech Briefs, March 1991, p.68): "Paradoxically, physically fit people lose tolerance to acceleration after bed rest more than sedentary people do." Grayout During ReentryYour body gets its worst beating during reentry. When the spacecraft plunges down through the atmosphere, deceleration causes a reversal or loss of blood flow in the temporal artery. Starved for blood oxygen, the brain slips into "grayout." Unconsciousness is not far away. This problem is even greater after prolonged weightlessness. Astronauts might reach Mars after an 18-month flight and pass out on the way to a landing -- or even worse. To test the effects of weightlessness (or "microgravity" to purists), confinement of bed rest was explored further. For greater accuracy, the beds were tilted a modest 6 degrees, with the heads slightly lower than the feet. This simulates the way fluids pool in the heads of astronauts, producing a stuffed-up nose. Future pop singers in space, take note. Twenty men between the ages of 35 and 50 endured ten days in bed, with centrifuge testing before and after. All subjects showed an increase in heart rate, and a decrease in blood plasma volume. But the thirteen men who were aerobically fit had a greater increase in heart rate, and a greater decrease in plasma than did the seven "sedentary" men. These seven, who were heavier, fattier, and started with lower maximal treadmill oxygen uptake, handled the bed rest deconditioning better. But wait, there's more. Before being exiled to the slanting bed, both fit and fat alike could handle an average of 370 seconds of 3-G acceleration in the centrifuge before they started to gray out. After a week, the physically fit men could only tolerate the acceleration for 111 seconds. Two of these prime specimens could barely handle the initial rise to 3-Gs. The overweight crew could go an average of 203 seconds -- almost twice as long -- without grayout. A Jumbo Pizza to Go, PleasePity the poor astronaut, who has dieted and worked out for nothing. Danielle J. Goldwater suggests that the aerobically fit astronauts might need special measures. Fluid loading and antigravity suits might be necessary to increase central blood volumes during reentry. Something must be done to reduce these people's loss of tolerance to acceleration during microgravity. But we can look at the results from a different angle. Being overweight, having more fat, having a faster heartbeat, and being able to gulp less oxygen while staggering on a treadmill -- these just might be the signs of tomorrow's spacemen and spacewomen. You are less likely to suffer from motion sickness in orbit. Your resting heart rate and blood plasma volume will prove more resistant to microgravity deconditioning. And when gravity returns with a vengeance during reentry, your brain will function better. So, space fans, that's why I'm stuffing my face right now. It isn't greed, it isn't gluttony, it isn't some neurotic weakness. I'm training for my future vacation in space. Forget about starving and sweating to lose a few pounds. You might be better off as you are. And why worry about a few pounds anyway? When you're in the "free fall" of orbit, you don't weigh anything at all. Extra fudge on my sundae, please! *** The End ***
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