首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
When scientists at the Australian Institute of Sport recently decided to check the Vitamin D status of some of that country’s el
When scientists at the Australian Institute of Sport recently decided to check the Vitamin D status of some of that country’s el
admin
2020-05-01
111
问题
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 though 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.
People can get vitamin D from the following EXCEPT______.
选项
A、Sunlight.
B、Cod-liver oil.
C、Medium exercise.
D、Supplements of Vitamin D.
答案
C
解析
由第一段可知,维生素D可通过晒太阳、饮食和补充剂来获取。
转载请注明原文地址:https://kaotiyun.com/show/1MbK777K
0
专业英语八级
相关试题推荐
AudienceAwarenessofWritingI.Introduction—contents,【T1】______andstylesdependontheaudience【T1】______—theimportance
A、Billionairesarequiterarenowadays.B、Forbes400includesbillionairesallovertheworld.C、Billionairesaremuchmorenow
A、Ithasproteininbrain.B、Itisfreeoffat.C、ItisfreeofvitaminD.D、Itisahappyfood.C根据句(3)可知,鱼是能令人开心的食物,鱼脑含有蛋白质,鱼肉
A、Byshowinglovelypicturesofdogs.B、Bypresentingvariousspeciesofdogs.C、Bypointingouttherelationshipbetweenhumans
PASSAGETHREEHowdoestheauthorfeelwhenhehearsapoliticiansay"Letmebeveryclear"inPara.12?
A、Highlevelofsomekindofhormone.B、Poorphysicalhealth.C、Agrumpylifestyle.D、Afamilyhistoryofbreastcancer.A本题设题点在
PASSAGETHREEWhatisthemainargumentofthispassage?
TheAmericanmedicalschoolisnowwellalonginthesecondcenturyofitshistory.Itbegan,butformanyyearscontinuedto【S1
(1)Don’talwaysbelievewhatscientistsandotherauthoritiestellyou!Beskeptical!Thinkcritically!That’swhatItellmys
随机试题
社稷祭祀属于()
营销传播中信息的发布者或直接传播者被称为()
治疗普通型流脑首选抗菌药物是
A.下颌骨体有大小不等的多房阴影B.下颌骨内有单房阴影,四周有白色骨质线C.颌骨内虫蚀状骨质破坏区,牙周骨质可有破坏D.下颌角见骨质疏松脱钙,并有骨增生E.下颌骨体有骨质破坏,并有死骨形成颌骨中央性骨癌X线表现为
引起恶性疟疾发作不规则的主要原因是
接触传染病病人后,刷手的时间是()
公司的领导人缺乏积极性和决心,已经与不断变化的外部环境失去了联系的企业倒闭类型是()。
某航空公司根据商务人员偏好快捷的交通方式、方便的行程安排以及舒适的服务这一特点推出了适合该类消费者的服务产品。根据以上信息可以判断该航空公司注意到了消费者的()。
AllofthefollowingdramasarecomediesofWilliamShakespeareexcept______.
Thehouseneedstoberepaired,______(房子的屋顶被大风摧毁了).
最新回复
(
0
)