021760秒科學人  

 今日主題:Beet Juice Could Help Body Beat Altitude  甜菜汁助你攀高峰<60秒科學人>

 洪欣老師推薦:托福聽力最好的課外教材:60-Second Science
 康康精選托福會考的主題,堅持每天精聽一定會進步的哦!!

 建議方法:
1. 先聽兩三遍 (不看文稿)
2. 再一句一句聽寫 (每句都要聽寫數遍,直到寫出85%以上的字)
3. 最後check文稿,看哪聽不出來,單字沒背過,還是發音不熟。
4. 堅持天天聽,就能每天進步哦。

 MP3音檔 (按右鍵可下載聽):喜歡的同學,幫忙推或按讚哦~~
http://online1.tingclass.net/voaspe/…/20151111sa_science.mp3

 只有音檔怎夠,聽不懂地方,不用怕,康康幫你準備好中英文稿了:

 中英文稿:
At 14,505 feet, Mount Whitney towers over California's Sierra Nevada range. It's the tallest peak in the lower 48—which means it attracts thousands of weekend warriors every year—or make that weakened warriors. You see them staggering along the narrow, rocky trail, huffing for air, dizzy and exhausted from the low oxygen levels at high elevation. And once they're sick? 
海拔14505英尺的惠特尼峰靜靜地佇立在加利福尼亞州。在內華達山脈較低的48座山峰中,惠特尼峰是最高的一座,這意味著它每年吸引了成千上萬的“週末戰士”(weekend warriors)——不如說是“週末顫 士”(weakened warriors)。他們在海拔高、氧含量低的情況下,沿著狹窄崎嶇的山道蹣跚而行。他們大口喘著粗氣,頭暈目眩、筋疲力盡——他們在途中生病了怎麼辦?

 

"The best medicine is to go down. That's actually the only cure that works." Svein Gaustad, a physiologist at the Norwegian University of Science and Technology. He says previous studies suggest blood vessels tend to contract at high altitudes, possibly because they need oxygen to relax—exactly what's in short supply on mountain tops. But there may be a dietary way to get more oxygen to your blood vessels: in the form of beet juice. The juice contains nitrate, which the body converts to nitric oxide, the compound that keeps arteries limber.
“再好的藥也比不過下山休息——實際上這也是唯一有效的方式。”來自挪威大學科學與技術學院的生理學家斯韋恩蓋於斯塔(Svein Gaustad)說道。他提到,先前的研究表明在高海拔地區,血管容易收縮。其中一部分原因在於血管需要靠氧氣才能鬆弛,而在高山上,氧氣恰恰是供不應求的。但也許可以通過飲食來為血管補充點氧氣:來點甜菜汁。甜菜汁裡有硝酸鹽,身體將其轉化為一氧化氮,而一氧化氮則可以保持動脈的彈性。

 

Gaustad and his colleagues tested that theory during a trek in Nepal, at 12,000 feet. Eight volunteers alternately drank shots of regular beet juice, and another day, beet juice with the nitrates stripped out. A few hours later, the researchers measured blood flow and artery diameters with ultrasound. And they found that the regular beet juice did indeed restore blood vessels back to their low-elevation flexibility, whereas the nitrate-stripped juice did not. The results are in the journal Nitric Oxide. [Emily Bakker et al, Acute dietary nitrate supplementation improves arterial endothelial function at high altitude: A double-blinded randomized controlled crossover study]
蓋於斯塔和他的同事徵集了八個志願者,在海拔12000英尺的尼泊爾進行長距離徒步。為了檢測他的理論,被試們一天喝普通甜菜汁,一天喝去掉硝酸鹽的甜菜汁。在喝完樣品的幾小時之後,研究者們用超聲波測量了血液流量和動脈直徑。他們發現普通甜菜汁確實將血管的柔韌性恢復到了低海拔時的水準,而去掉硝酸鹽的甜菜汁卻沒有這個作用。相關結果已發表在Nitric Oxide雜誌上。

 

Gaustad says better vascular function has the potential to deliver more blood—and therefore more oxygen—to tired muscles. But they still don't know if that translates to better performance at altitude. And, he says, beets won't hurt, but they're no substitute for proper acclimatization. "If I had a bottle of beets around I would take it for sure. But that won't bring you to Mount Everest just by drinking beetroot."
蓋於斯塔說血管功能越好,運輸血液的能力越強,因此能輸送更多氧氣來緩解肌肉疲勞。但是他們仍然不知道這是否意味著食用甜菜汁是否能在高海拔地區提高運動能力。他說,喝甜菜汁沒什麼壞處,但它們不能代替我們身體去適應高海拔氣候。“如果我有一瓶甜菜汁,我會喝它,但只是喝喝甜菜汁可不能把你帶到珠穆朗瑪峰。”。

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