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健康知识(英文)

2017-09-05 32页 doc 104KB 31阅读

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健康知识(英文)1. Phys Ed: Why Doesn??t Exercise Lead to Weight Loss? By Gretchen Reynolds Sven Hagolani/Getty Images For some time, researchers have been finding that people who exercise don??t necessarily lose weight. A study published online in September in The British Journ...
健康知识(英文)
1. Phys Ed: Why Doesn??t Exercise Lead to Weight Loss? By Gretchen Reynolds Sven Hagolani/Getty Images For some time, researchers have been finding that people who exercise don??t necessarily lose weight. A study published online in September in The British Journal of Sports Medicine was the latest to report apparently disappointing slimming results. In the study, 58 obese people completed 12 weeks of supervised aerobic training without changing their diets. The group lost an average of a little more than seven pounds, and many lost barely half that. How can that be? Exercise, it seems, should make you thin. Activity burns calories. No one doubts that. ??Walking, even at a very easy pace, you??ll probably burn three or four calories a minute,?? beyond what you would use quietly sitting in a chair, said Dan Carey, Ph.D., an assistant professor of exercise physiology at the University of St. Thomas in Minnesota, who studies exercise and metabolism. But few people, an overwhelming body of research shows, achieve significant weight loss with exercise alone, not without changing their eating habits. A new study from scientists at the University of Colorado School of Medicine in Denver offers some reasons why. For the study, the researchers recruited several groups of people. Some were lean endurance athletes; some sedentary and lean; some sedentary and obese. Each of the subjects agreed to spend, over the course of the experiment, several 24-hour periods in a special laboratory room (a walk-in calorimeter) that measures the number of calories a person burns. Using various calculations, the researchers could also tell whether the calories expended were in the form of fat or carbohydrates, the body??s two main fuel sources. Burning more fat than carbohydrates is obviously desirable for weight loss, since the fat being burned comes primarily from body fat stores, and we all, even the leanest among us, have plenty of those. The Denver researchers were especially interested in how the athletes?? bodies would apportion and use calories. It has been well documented that regular endurance training increases the ability of the body to use fat as a fuel during exercise. They wondered, though, if the athletes ?ª or any of the other subjects ?ª would burn extra fat calories after exercising, a phenomenon that some exercisers (and even more diet and fitness books) call ??afterburn.?? ??Many people believe that you rev up?? your metabolism after an exercise session ??so that you burn additional body fat throughout the day,?? said Edward Melanson, Ph.D., an associate professor in the division of endocrinology at the School of Medicine and the lead author of the study. If afterburn were found to exist, it would suggest that even if you replaced the calories you used during an exercise session, you should lose weight, without gaining weight ?ª the proverbial free lunch. Each of Melanson??s subjects spent 24 quiet hours in the calorimeter, followed later by another 24 hours that included an hourlong bout of stationary bicycling. The cycling was deliberately performed at a relatively easy intensity (about 55 percent of each person??s predetermined aerobic capacity). It is well known physiologically that, while high-intensity exercise demands mostly carbohydrate calories (since carbohydrates can quickly reach the bloodstream and, from there, laboring muscles), low-intensity exercise prompts the body to burn at least some stored fat. All of the subjects ate three meals a day. To their surprise, the researchers found that none of the groups, including the athletes, experienced ??afterburn.?? They did not use additional body fat on the day when they exercised. In fact, most of the subjects burned slightly less fat over the 24-hour study period when they exercised than when they did not. ??The message of our work is really simple,?? although not agreeable to hear, Melanson said. ??It all comes down to energy balance,?? or, as you might have guessed, calories in and calories out. People ??are only burning 200 or 300 calories?? in a typical 30-minute exercise session, Melanson points out. ??You replace that with one bottle of Gatorade.?? This does not mean that exercise has no impact on body weight, or that you can??t calibrate your workouts to maximize the amount of body fat that you burn, if that??s your goal. ??If you work out at an easy intensity, you will burn a higher percentage of fat calories?? than if you work out a higher intensity, Carey says, so you should draw down some of the padding you??ve accumulated on the hips or elsewhere ?ª if you don??t replace all of the calories afterward. To help those hoping to reduce their body fat, he published formulas in The Journal of Strength and Conditioning Research last month that detailed the heart rates at which a person could maximize fat burning. ??Heart rates of between 105 and 134?? beats per minute, Carey said, represent the fat-burning zone. ??It??s probably best to work out near the top of that zone,?? he says, ??so that you burn more calories over all?? than at the extremely leisurely lower end. Perhaps just as important, bear in mind that exercise has benefits beyond weight reduction. In the study of obese people who took up exercise, most became notably healthier, increasing their aerobic capacity, decreasing their blood pressure and resting heart rates, and, the authors write, achieving ??an acute exercise-induced increase in positive mood,?? leading the authors to conclude that, ??significant and meaningful health benefits can be achieved even in the presence of lower than expected exercise-induced weight loss.?? Finally and thankfully, exercise seems to aid, physiologically, in the battle to keep off body fat once it has been, through resolute calorie reduction, chiseled away. In other work by Melanson??s group, published in September, laboratory rats that had been overfed and then slimmed through calorie reduction were able to ??defend?? their lower weight more effectively if they ran on a treadmill and ate at will than if they had no access to a treadmill. The exercise seemed to reset certain metabolic pathways within the rats, Melanson says, that blunted their body??s drive to replace the lost fat. Similar mechanisms, he adds, probably operate within the bodies of humans, providing scientific justification for signing up for that Thanksgiving Day 5K. 2.Phys Ed: Does Exercise Boost Immunity? By Gretchen Reynolds Marc Romanelli/Getty Images Two recent experiments hit rather close to home at this time of year. In the first, published last year in the journal Brain, Behavior, and Immunity, researchers divided mice into two groups. One rested comfortably in their cages. The other ran on little treadmills until they were exhausted. This continued for three days. The mice were then exposed to an influenza virus. After a few days, more of the mice who??d exhausted themselves running came down with the flu than the control mice. They also had more severe symptoms. In the second experiment, published in the same journal, scientists from the University of Illinois and other schools first infected laboratory mice with flu. One group then rested; a second group ran for a leisurely 20 or 30 minutes, an easy jog for a mouse; the third group ran for a taxing two and a half hours. Each group repeated this routine for three days, until they began to show flu symptoms. The flu bug used in this experiment is devastating to rodents, and more than half of the sedentary mice died. But only 12 percent of the gently jogging mice passed away. Meanwhile, an eye-popping 70 percent of the mice in the group that had run for hours died, and even those that survived were more debilitated and sick than the control group. Is this good news or bad? This is a particularly relevant question as two important human events converge: the peaking of the fall marathon and other sports seasons and the simultaneous onset of the winter cold and flu term. Scientists are diligently working to answer that question, perhaps because they are as interested as the rest of us in avoiding or lessening the severity of colds and the flu. The bulk of the new research, including the mouse studies mentioned, reinforce a theory that physiologists advanced some years ago, about what they call ??a J-shaped curve?? involving exercise and immunity. In this model, the risk both of catching a cold or the flu and of having a particularly severe form of the infection ??drop if you exercise moderately,?? says Mary P. Miles, PhD, an associate professor of exercise sciences at Montana State University and the author of an editorial about exercise and immunity published in the most recent edition of the journal Exercise and Sport Sciences Review. But the risk both of catching an illness and of becoming especially sick when you do ??jump right back up?? if you exercise intensely or for a prolonged period of time, surpassing the risks among the sedentary. (Although definitions of intense exercise vary among researchers, most define it as a workout or race of an hour or more during which your heart rate and respiration soar and you feel as if you are working hard.) Why exercise should affect either your susceptibility to catching an illness or how badly a particular bug affects you is still unclear. But it does appear that intense workouts and racing suppress the body??s immune response for a period of time immediately after you??ve finished exercising and that ??the longer the duration and the more intense?? the exercise, ??the longer the temporary period of immunosuppression lasts ?ª anything from a few hours to a few days has been suggested,?? says Nicolette Bishop, an associate professor of sport and exercise sciences at Loughborough University and the author of a review article about exercise and immunity published in January. A telling new study, published in August in the Journal of Strength and Conditioning Research, looked at cellular markers of immune system activity in the saliva of twenty-four, Spanish, professional soccer players, before and after a strenuous, 70-minute match. Before play, the saliva of most of the players showed normal levels of immunoglobulins, substances that help to fight off infection. Afterward, concentrations of saliva immunoglobulins in many of them had fallen dramatically. If scientists aren??t sure yet why intense exercise temporarily depresses the immune system, however, they seem to be closer to understanding why, once you??ve caught a bug, intense exercise can make the symptoms and severity worse. In work at the University of Illinois, reported last month in the journal Exercise and Sport Sciences Review, some of the same scientists who??d studied mice and flu looked at just what was going on inside the cells of the affected animals. They found that the leisurely jogging rodents showed signs of a very particular immune response to the flu. In general, and this is true in both mice and men, says Jeffrey A. Woods, a professor of kinesiology and community health at the University of Illinois and one of the scientists involved, viruses evoke an increase in what are called T1-type helper immune cells. These T1-helper cells induce inflammation and other changes in the body that represent a first line of defense against an invading virus. But if the inflammation, at first so helpful, continues for too long, it becomes counterproductive. The immune system needs, then, at some point to lessen the amount of T1-mediated inflammatory response, so that, in fighting the virus, it doesn??t accidentally harm its own host. The immune system does this by gradually increasing the amount of another kind of immune cell, T2-helper cells, which produce mostly an anti-inflammatory immune response. They??re water to the T1 fire. But the balance between the T1- and T2-helper cells must be exquisitely calibrated. In the mice at the University of Illinois, moderate exercise subtly hastened the shift from a T1 response to a T2-style immune response ?ª not by much, but by just enough, apparently, to have a positive impact against the flu. ??Moderate exercise appears to suppress TH1 a little, increase TH2 a little,?? Woods says. On the other hand, intense or prolonged exercise ??may suppress TH1 too much,?? he says. Long, hard runs or other workouts may shut down that first line of defense before it has completed its work, which could lead, Woods says ??to increased susceptibility to viral infection.?? So, if you have just completed a strenuous 20-mile training run and have, in consequence, a depressed immune response, avoid colleagues who are sniffling. Wash your hands often. ??I would recommend everyone get the annual influenza vaccination and the new H1N1 vaccination,?? Woods says. But if all of that has been for naught and you now feel the early stirrings of sickness, ??listen to your body and be prudent in your exercise decisions,?? Woods says. In general, moderate exercise, such as a leisurely jog or walk, may prop up your immune response and lessen the duration and severity of a mild infection, but be honest about your condition. ??If you don??t feel well, especially if you have fever or body aches, I would recommend stopping daily exercise until you are recovered,?? Woods says. ??It is okay to exercise if you have a simple head cold or congestion ?ª in fact, it may improve the way you feel. I would avoid heavy, prolonged exercise with a head cold, though,?? since it can unbalance that important T1 and T2-helper cell response. And take comfort in the results of the most recent study to look at actual, practicing marathoners. In it, 1,694 runners at the 2000 Stockholm Marathon informed researchers about any colds or other infectious illness they developed in the three weeks before or three weeks after the race. Nearly one-fifth of the runners fell ill during that time period. That??s higher than the rates in people generally, but it still means that the overwhelming majority of runners didn??t get sick. 3.Phys Ed: What Sort of Exercise Can Make You Smarter? By Gretchen Reynolds Nick Veasey/Getty Images Allow a laboratory mouse to run as much as it likes, and its brainpower improves. Force it to run harder than it otherwise might, and its thinking improves even more. This is the finding of an experiment led by researchers at National Cheng Kung University in Taiwan and placed online in May. In the study, scientists had two groups of mice swim a water maze and in a separate trial had them endure an unpleasant stimulus to see how quickly they would learn to move away from it. For the next four weeks they allowed one group of mice to run inside their rodent wheels, an activity most mice enjoy, while requiring the other group to push harder on minitreadmills at a speed and duration controlled by the scientists. They then tested both groups again to track their learning skills and memory. Both groups of mice performed admirably in the water maze, bettering their performances from the earlier trial. But only the treadmill runners were better in the avoidance task, a skill that, according to brain scientists, demands a more complicated cognitive response. The mice who raced on the treadmills showed evidence of molecular changes in several portions of their brains when viewed under a microscope, while the voluntary wheel-runners had changes in only one area. ??Our results support the notion that different forms of exercise induce neuroplasticity changes in different brain regions,?? Chauying J. Jen, a professor of physiology and an author of the study, says. For some time, researchers have known that exercise changes the structure of the brain and affects thinking. Ten years ago scientists at the Salk Institute in California published the groundbreaking finding that exercise stimulates the creation of new brain cells. But fundamental questions remain, like whether exercise must be strenuous to be beneficial. Should it be aerobic? What about weight lifting? And are the cognitive improvements permanent or fleeting? Other recent studies provide some preliminary answers. In an experiment published in the journal of the American College of Sports Medicine, 21 students at the University of Illinois were asked to memorize a string of letters and then pick them out from a list flashed at them. Then they were asked to do one of three things for 30 minutes ?ª sit quietly, run on a treadmill or lift weights ?ª before performing the letter test again. After an additional 30-minute cool down, they were tested once more. On subsequent days, the students returned to try the other two options. The students were noticeably quicker and more accurate on the retest after they ran compared with the other two options, and they continued to perform better when tested after the cool down. ??There seems to be something different about aerobic exercise,?? Charles Hillman, an associate professor in the department of kinesiology at the University of Illinois and an author of the study, says. Similarly, in other work by scientists at the University of Illinois, elderly people were assigned a six-month program of either stretching exercises or brisk walking. The stretchers increased their flexibility but did not improve on tests of cognition. The brisk walkers did. Why should exercise need to be aerobic to affect the brain? ??It appears that various growth factors must be carried from the periphery of the body into the brain to start a molecular cascade there,?? creating new neurons and brain connections, says Henriette van Praag, an investigator in the Laboratory of Neurosciences at the National Institute on Aging. For that to happen, ??you need a fairly dramatic change in blood flow,?? like the one that occurs when you run or cycle or swim. Weight lifting, on the other hand, stimulates the production of ??growth factors in the muscles that stay in the muscles and aren??t transported to the brain,?? van Praag says. What then of the Taiwanese mice, all of which ran? According to the investigators, mice on a running wheel ??usually show little improvements in the conventionally defined?? measurements of fitness, like elevated muscle strength and improved aerobic capacity. They enjoy themselves; they don??t strain. Those on the treadmill, meanwhile, are forced to pant and puff. Jen says researchers suspect that treadmill running is more intense and leads to improvements in ??muscle aerobic capacity,?? and this increased aerobic capacity, in turn, affects the brain more than the wheel jogging. Does this mean we should relinquish control of our workouts to a demanding coach? Jen cautions against assuming human bodies work exactly like those of rats. But there are lessons from his work. ??It would be fair to say that any form of regular exercise,?? he says, if it is aerobic, ??should be able to maintain or even increase our brain functions.?? 4.Phys Ed: Can Vitamin D Improve Your Athletic Performance? By Gretchen Reynolds Patrik Giardino/Getty Images When scientists at the Australian Institute of Sport recently decided to check the Vitamin D status of some of that country??s elite female gymnasts, their findings were fairly alarming. Of the 18 gymnasts tested, 15 had levels that were ??below current recommended guidelines for optimal bone health,?? the study??s authors report. Six of these had Vitamin D levels that would qualify as medically deficient. Unlike other nutrients, Vitamin D can be obtained by exposure to ultraviolet radiation from sunlight, as well as through foods or supplements. Of course, female gymnasts are a unique and specialized bunch, not known for the quality or quantity of their diets, or for getting outside much. But in another study presented at a conference earlier this year, researchers found that many of a group of distance runners also had poor Vitamin D status. Forty percent of the runners, who trained outdoors in sunny Baton Rouge, Louisiana, had insufficient Vitamin D. ??It was something of a surprise,?? says D. Enette Larson-Meyer, an assistant professor in the Department of Family and Consumer Sciences at the University of Wyoming and one of the authors of the study. Vitamin D is an often overlooked element in athletic achievement, a ??sleeper nutrient,?? says John Anderson, a professor emeritus of nutrition at the University of North Carolina and one of the authors of a review article published online in May about Vitamin D and athletic performance. Vitamin D once was thought to be primarily involved in bone development. But a growing body of research suggests that it??s vital in multiple different bodily functions, including allowing body cells to utilize calcium (which is essential for cell metabolism), muscle fibers to develop and grow normally, and the immune system to function properly. ??Almost every cell in the body has receptors?? for Vitamin D, Anderson says. ??It can up-regulate and down-regulate hundreds, maybe even thousands of genes,?? Larson-Meyer says. ??We??re only at the start of understanding how important it is.?? But many of us, it seems, no matter how active and scrupulous we are about health, don??t get enough Vitamin D. Nowadays, ??many people aren??t going outside very much,?? Johnson says, and most of us assiduously apply sunscreen and take other precautions when we do. The Baton Rouge runners, for instance, most likely ??ran early in the morning or late in the day,?? Larson-Meyer says, reducing their chances of heat stroke or sunburn, but also reducing their exposure to sunlight. Meanwhile, dietary sources of Vitamin D are meager. Cod-liver oil provides a whopping dose. But a glass of fortified milk provides a fraction of what scientists now think we need per day. (A major study published online in the journal Pediatrics last month concluded that more than 60 percent of American children, or almost 51 million kids, have ??insufficient?? levels of Vitamin D and another 9 percent, or 7.6 million children, are clinically ??deficient,?? a serious condition. Cases of childhood rickets, a bone disease caused by lack of Vitamin D, have been rising in the U.S. in recent years.) Although few studies have looked closely at the issue of Vitamin D and athletic performance, those that have are suggestive. A series of strange but evocative studies undertaken decades ago in Russia and Germany, for instance, hint that the Eastern Bloc nations may have depended in part on sunlamps and Vitamin D to produce their preternaturally well-muscled and world-beating athletes. In one of the studies, four Russian sprinters were doused with artificial, ultraviolet light. Another group wasn??t. Both trained identically for the 100-meter dash. The control group lowered their sprint times by 1.7 percent. The radiated runners, in comparison, improved by an impressive 7.4 percent. More recently, when researchers tested the vertical jumping ability of a small group of adolescent athletes, Larson-Meyer says, ??they found that those who had the lowest levels of Vitamin D tended not to jump as high,?? intimating that too little of the nutrient may impair muscle power. Low levels might also contribute to sports injuries, in part because Vitamin D is so important for bone and muscle health. In a Creighton University study of female naval recruits, stress fractures were reduced significantly after the women started taking supplements of Vitamin D and calcium. A number of recent studies also have shown that, among athletes who train outside year-round, maximal oxygen intake tends to be highest in late summer, Johnson says. The athletes, in other words, are fittest in August, when ultraviolet radiation from the sun is near its zenith. They often then experience an abrupt drop in maximal oxygen intake, beginning as early as September, even thought they continue to train just as hard. This decline coincides with the autumnal lengthening of the angle of sunlight. Less ultraviolet radiation reaches the earth and, apparently, sports performance suffers. Concerned now about your Vitamin D status? You can learn your status with a simple blood test. An at-home version is available through the Web site of the Vitamin D Council. (Use of the tests is restricted in some states, including New York. See the website for details.) Be sure that any test checks the level of 25(OH)D in your blood. This level ??should generally be above 50 nanograms per milliliter,?? Larson-Meyer says. If your levels are low, talk to your doctor about the best response. Sunlight is one easy, if controversial, fix. ??Most dermatologists will still tell you that no amount of sun exposure is safe,?? Johnson says. But Larson-Meyer and other Vitamin D researchers aren??t so sure. ??There??s no good, scientific evidence that five to thirty minutes of sunlight a few times a week is harmful,?? she says. Or try supplements. ??1,000 IU a day and much more for people who are deficient?? is probably close to ideal, Larson-Meyer says. This, by the way, is about double the current recommended daily allowance. Most experts anticipate that this allowance will be revised upward soon. Consult with your doctor before beginning supplements. Overdoses of Vitamin D are rare, but can occur. Finally, stay tuned. ??In the next few years, we??re going to be learning much more?? about the role of vitamin D in bodily function and sports performance, Larson-Meyer says. 5.Phys Ed: Does Ibuprofen Help or Hurt During Exercise? By Gretchen Reynolds Dan Saelinger/Getty Images Several years ago, David Nieman set out to study racers at the Western States Endurance Run, a 100-mile test of human stamina held annually in the Sierra Nevada Mountains of California. The race directors had asked Nieman, a well-regarded physiologist and director of the Human Performance Laboratory at the North Carolina Research Campus, to look at the stresses that the race places on the bodies of participants. Nieman and the race authorities had anticipated that the rigorous distance and altitude would affect runners?? immune systems and muscles, and they did. But one of Nieman??s other findings surprised everyone. After looking at racers?? blood work, he determined that some of the ultramarathoners were supplying their own physiological stress, in tablet form. Those runners who??d popped over-the-counter ibuprofen pills before and during the race displayed significantly more inflammation and other markers of high immune system response afterward than the runners who hadn??t taken anti-inflammatories. The ibuprofen users also showed signs of mild kidney impairment and, both before and after the race, of low-level endotoxemia, a condition in which bacteria leak from the colon into the bloodstream. These findings were ??disturbing,?? Nieman says, especially since ??this wasn??t a minority of the racers.?? Seven out of ten of the runners were using ibuprofen before and, in most cases, at regular intervals throughout the race, he says. ??There was widespread use and very little understanding of the consequences.?? Athletes at all levels and in a wide variety of sports swear by their painkillers. A study published earlier this month on the website of the British Journal of Sports Medicine found that, at the 2008 Ironman Triathlon in Brazil, almost 60 percent of the racers reported using non-steroidal anti-inflammatory painkillers (or NSAIDs, which include ibuprofen) at some point in the three months before the event, with almost half downing pills during the race itself. In another study, about 13 percent of participants in a 2002 marathon in New Zealand had popped NSAIDs before the race. A study of professional Italian soccer players found that 86 percent used anti-inflammatories during the 2002-2003 season. A wider-ranging look at all of the legal substances prescribed to players during the 2002 and 2006 Men??s World Cup tournaments worldwide found that more than half of these elite players were taking NSAIDS at least once during the tournament, with more than 10 percent using them before every match. ??For a lot of athletes, taking painkillers has become a ritual,?? says Stuart Warden, an assistant professor and director of physical therapy research at Indiana University, who has extensively studied the physiological impacts of the drugs. ??They put on their uniform?? or pull on their running shoes and pop a few Advil. ??It??s like candy?? or Vitamin I, as some athletes refer to ibuprofen. Why are so many active people swallowing so many painkillers? One of the most common reasons cited by the triathletes in Brazil was ??pain prevention.?? Similarly, when the Western States runners were polled, most told the researchers that ??they thought ibuprofen would get them through the pain and discomfort of the race,?? Nieman says, ??and would prevent soreness afterward.?? But the latest research into the physiological effects of ibuprofen and other NSAIDs suggests that the drugs in fact, have the opposite effect. In a number of studies conducted both in the field and in human performance laboratories in recent years, NSAIDs did not lessen people??s perception of pain during activity or decrease muscle soreness later. ??We had researchers at water stops?? during the Western States event, Nieman says, asking the racers how the hours of exertion felt to them. ??There was no difference between the runners using ibuprofen and those who weren??t. So the painkillers were not useful for reducing pain?? during the long race, he says, and afterward, the runners using ibuprofen reported having legs that were just as sore as those who hadn??t used the drugs. Moreover, Warden and other researchers have found that, in laboratory experiments on animal tissues, NSAIDs actually slowed the healing of injured muscles, tendons, ligament, and bones. ??NSAIDs work by inhibiting the production of prostaglandins,??substances that are involved in pain and also in the creation of collagen, Warden says. Collagen is the building block of most tissues. So fewer prostaglandins mean less collagen, ??which inhibits the healing of tissue and bone injuries,?? Warden says, including the micro-tears and other trauma to muscles and tissues that can occur after any strenuous workout or race. The painkillers also blunt the body??s response to exercise at a deeper level. Normally, the stresses of exercise activate a particular molecular pathway that increases collagen, and leads, eventually, to creating denser bones and stronger tissues. If ??you??re taking ibuprofen before every workout, you lessen this training response,?? Warden says. Your bones don??t thicken and your tissues don??t strengthen as they should. They may be less able to withstand the next workout. In essence, the pills athletes take to reduce the chances that they??ll feel sore may increase the odds that they??ll wind up injured ?ª and sore. All of which has researchers concerned. Warden wrote in an editorial this year on the website of the British Journal of Sports Medicine that ??there is no indication or rationale for the current prophylactic use of NSAIDs by athletes, and such ritual use represents misuse.?? When, then, are ibuprofen and other anti-inflammatory painkillers justified? ??When you have inflammation and pain from an acute injury,?? Warden says. ??In that situation, NSAIDs are very effective.?? But to take them ??before every workout or match is a mistake.?? 6.Phys Ed: Is Quercetin Really a Wonder Sports Supplement? By Gretchen Reynolds Marvin Orellana/The New York Times Quercetin tablets. For a while, it looked as if quercetin might be the next super-supplement, one of the few legal substances able to improve athletic performance. Quercetin is a flavonoid found naturally in apple skins, berries, red wine, black tea and some leafy vegetables. Like other flavonoids, it is believed to be an antioxidant, a substance that can lessen or prevent certain kinds of cell damage, and an anti-inflammatory. But of even more importance to athletes, it has shown evidence of being a potent performance enhancer in mice. In a representative animal study, published earlier this year, lab mice ran on a wheel or treadmill to gauge their fitness. Then some mice received large doses of quercetin for a week; others received a placebo. None of the rodents exercised. At the end of the week, the mice ran again. The quercetin mice were able to run as much as 37 percent longer than they had the week before. The placebo group showed no improvement. Meanwhile, analysis of the muscles and brains of some of the quercetin group showed new mitochondria ?ª which help to produce energy ?ª packing the cells. The placebo group had no new mitochondria. All indications, then, were that quercetin was energizing the mice at a fundamental, cellular level. Such results galvanized physiologists, coaches and athletes, especially after F.R.S., a company that had developed a sports drink containing quercetin, financed a small study published in 2006 of highly trained human cyclists. It showed that those quaffing the sports drink ??significantly improved high-intensity cycling time-trial performance through enhancement of power output,?? as the authors wrote. Not long afterward, the Tour de France winner Lance Armstrong, arguably the world??s most famous endurance athlete, signed on to the board and became a promoter. Quercetin popped up as a common topic on Internet sites devoted to running and cycling. One of the mouse researchers declared in a video available on the F.R.S. Web site that ??quercetin could turn out to be one of the most important discoveries in nutrition in a very long time.?? But it turned out that the cyclists in the 2006 study also improved their performance after taking a placebo. Other quercetin studies of people were then undertaken. One, published in June, provided quercetin to 12 healthy, untrained men for a week and found that they exercised for a longer period of time after taking quercetin than before. But three other studies have been, as a lead researcher of one of them says, ??disappointing.?? Runners, for instance, who volunteered to use quercetin before the Western States Endurance Run, a grueling 100-mile race in California, finished no faster than those who didn??t take the supplement. A separate experiment by the same researchers, published this year, found similar results in well-trained cyclists. The quercetin group rode no farther or harder. The largest and most comprehensive study was reported in August in The Journal of Applied Physiology. It was conducted at the University of Georgia with a group of 30 healthy but untrained young men. The researchers hypothesized that quercetin might have failed to help trained athletes because they already had maximized their mitochondrial production through aerobic exercise; their cells could hold no more, and so the quercetin had no effect. In the untrained, they thought, the supplement might stimulate new mitochondria and improve athletic performance. Their experiment was financed by Coca-Cola, which was testing a new sports drink with quercetin. The researchers first tested the volunteers?? fitness, then had half the group drink Coca-Cola??s proposed quercetin drink twice a day during the study period, which ranged from a week to 16 days (based on when volunteers could return for retesting). The other half received the same fluid, minus the supplement. The dosage of quercetin mimicked the amount given to mice, adjusted to human size. None of the volunteers exercised during that period. At the end of this time, the subjects were retested, with provocative results. ??There were simply no differences?? between the quercetin and the placebo group, says Kirk J. Cureton, a professor of kinesiology at the University of Georgia and lead author of the study. The quercetin group didn??t ride farther before exhaustion. Their bodies showed no evidence of new mitochondrial production. ??We were surprised,?? Cureton says. ??Based on the mouse studies, we had expected?? that the supplement would have a positive impact. Obviously, he continues, one study is not definitive. Different doses of quercetin or use for a longer time might lead to different results. ??But my conclusion is that it just is not ergogenic in humans,?? Cureton says. It doesn??t improve performance. ??The moral is that you can??t generalize from mouse studies to humans.?? And you can??t, as anyone who has followed sports nutrition should perhaps have learned by now, expect improved performance to be delivered, without effort, in pill or liquid form. 7.You??re Sick. Now What? Knowledge Is Power. Are patients swimming in a sea of health information? Or are they drowning in it? Skip to next paragraph Enlarge This Image Illustration by Nola Lopez, with Anatomical Images by Bryan Christie Special Section Decoding Your Health SEARCHING FOR CLARITY A Primer on Medical Studies KNOWLEDGE IS POWER You??re Sick. Now What? GOOGLING YOUR HEALTH The exploding online universe. WHERE TO CLICK Reviews of six popular health Web sites. THE REGULATORS What does ??F.D.A. approved?? mean? ESSAY Dr. Abigail Zuger on the meaning of ??healthy.?? BEYOND THE YELLOW PAGES Finding the right doctor. THE COUNT How to read that printout from your blood test. SECOND OPINION Denise Grady on self-diagnosis. DOCTOR AND PATIENT Dr. Pauline W. Chen on candor. SOURCES Our writers choose some of their favorites. EVIDENCE HUNTERS Testing claims for alternative medicine. PERSONAL HEALTH Jane E. Brody on the primary care crisis. Readers?? Opinions Join the Discussion at the Well Blog Audio David Corcoran, a science editor, explores some of the topics addressed in this week??s Science Times. Podcast: Science Update RSS Feed Get Health News From The New York Times ? The rise of the Internet, along with thousands of health-oriented Web sites, medical blogs and even doctor-based television and radio programs, means that today??s patients have more opportunities than ever to take charge of their medical care. Technological advances have vastly increased doctors?? diagnostic tools and treatments, and have exponentially expanded the amount of information on just about every known disease. The daily bombardment of news reports and drug advertising offers little guidance on how to make sense of self-proclaimed medical breakthroughs and claims of worrisome risks. And doctors, the people best equipped to guide us through these murky waters, are finding themselves with less time to spend with their patients. But patients have more than ever to gain by decoding the latest health news and researching their own medical care. ??I don??t think people have a choice ?ª it??s mandatory,?? said Dr. Marisa Weiss, a breast oncologist in Pennsylvania who founded the Web site breastcancer.org. ??The time you have with your doctor is getting progressively shorter, yet there??s so much more to talk about. You have to prepare for this important meeting.?? Whether you are trying to make sense of the latest health news or you have a diagnosis of a serious illness, the basic rules of health research are the same. From interviews with doctors and patients, here are the most important steps to take in a search for medical answers. Determine your information personality. Information gives some people a sense of control. For others, it??s overwhelming. An acquaintance of this reporter, a New York father coping with his infant son??s heart problem, knew he would be paralyzed with indecision if his research led to too many choices. So he focused on finding the area??s best pediatric cardiologist and left the decisions to the experts. Others, like Amy Haberland, 50, a breast cancer patient in Arlington, Mass., pore through medical journals, looking not just for answers but also for better questions to ask their doctors. ??Knowledge is power,?? Ms. Haberland said. ??I think knowing the reality of the risks of my cancer makes me more comfortable undergoing my treatment.?? Dr. Michael Fisch, interim chairman of general oncology for the University of Texas M. D. Anderson Cancer Center, says that before patients embark on a quest for information, they need to think about their goals and how they might react to information overload. ??Just like with medicine, you have to ask yourself what dose you can take,?? he said. ??For some people, more information makes them wackier, while others get more relaxed and feel more empowered.?? The goal is to find an M.D., not become one. Often patients begin a medical search hoping to discover a breakthrough medical study or a cure buried on the Internet. But even the best medical searches don??t always give you the answers. Instead, they lead you to doctors who can provide you with even more information. ??It??s probably the most important thing in your cancer care that you believe someone has your best interests at heart,?? said Dr. Anna Pavlick, director of the melanoma program at the New York University Cancer Institute. ??In an area where there are no right answers, you??re going to get a different opinion with every doctor you see. You??ve got to find a doctor you feel most comfortable with, the one you most trust.?? Keep statistics in perspective. Patients researching their health often come across frightening statistics. Statistics can give you a sense of overall risk, but they shouldn??t be the deciding factor in your care. Jolanta Stettler, 39, of Denver, was told she had less than six months to live after getting a diagnosis of ocular melanoma, a rare cancer of the eye that had spread to her liver. ??I was told there is absolutely nothing they could help me with, no treatment,?? said Ms. Stettler, a mother of three. ??I was left on my own.?? Ms. Stettler and her husband, a truck driver, began searching the Internet. She found Dr. Charles Nutting, an interventional radiologist at Swedish Medical Center in Englewood, Colo., who was just beginning to study a treatment that involves injecting tiny beads that emit small amounts of radiation. That appeared to help for about 18 months. When her disease progressed again, Ms. Stettler searched for clinical trials of treatments for advanced ocular melanoma, and found a National Institutes of Health study of ??isolated hepatic perfusion,?? which delivers concentrated chemotherapy to patients with liver metastases. After the first treatment, Ms. Stettler??s tumors had shrunk by half. ??I don??t like statistics,?? she said. ??If this study stops working for me, I??ll go find another study. Each type of treatment I have is stretching out my life. It gives me more time, and it gives more time to the people who are working really hard to come up with a treatment for this cancer.?? Don??t limit yourself to the Web. There??s more to decoding your health than the Web. Along with your doctor, your family, other patients and support groups can be resources. So can the library. When she found out she had Type 2 diabetes in 2006, Barbara Johnson, 53, of Chanhassen, Minn., spent time on the Internet, but also took nutrition classes and read books to study up on the disease. ??I was blindsided ?ª I didn??t know anybody who had it,?? said Ms. Johnson, who told her story on the American Heart Association??s Web site, IKnowDiabetes.org. ??But this is a disease you have to manage yourself.?? Tell your doctor about your research. Often patients begin a health search because their own doctors don??t seem to have the right answers. All her life, Lynne Kaiser, 44, of Plano, Tex., suffered from leg pain and poor sleep; her gynecologist told her she had ??extreme PMS.?? But by searching the medical literature for ??adult growing pains,?? she learned about restless legs syndrome and a doctor who had studied it. ??I had gone to the doctors too many times and gotten no help and no results,?? said Ms. Kaiser, who is now a volunteer patient advocate for the Web site WhatIsRLS.org. The new doctor she found ??really pushed me to educate myself further and pushed me to look for support.?? Although some doctors may discourage patients from doing their own research, many say they want to be included in the process. Dr. Fisch of M. D. Anderson recalls a patient with advanced pancreatic cancer who decided against conventional chemotherapy, opting for clinical trials and alternative treatments. But instead of sending her away, Dr. Fisch said he kept her in the ??loop of care.?? He even had his colleagues use a mass spectroscopy machine to evaluate a blue scorpion venom treatment the patient had stumbled on. It turned out to be just blue water. ??We monitored no therapy like we would anything else, by watching her and staying open to her choices,?? Dr. Fisch said. ??She lived about a year from the time of diagnosis, and she had a high quality of life.?? Dr. Shalom Kalnicki, chairman of Radiation Oncology at the Montefiore-Einstein Cancer Center, says he tries to guide his patients, explaining the importance of peer-reviewed information to help them filter out less reliable advice. He also encourages them to call or e-mail him with questions as they ??study their own case.?? ??We need to help them sort through it, not discourage the use of information,?? he said. ??We have to acknowledge that patients do this research. It??s important that instead of fighting against it, that we join them and become their coaches in the process.??
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