2006年NPR美国国家公共电台八月-Athletes Run Risk of Over-Hydrating

Training for a marathon or an Ironman, how much you drink is important. Of course, there's the risk of dehydration¹, but athletes now know they can also get into trouble by drinking too much which dilute² levels of sodium³ in the blood.

The death of one 28-year-old woman following the 2002 Boston Marathon led to new research and experts say to strike the right balance, the best strategy is to replace or put back in your body through drinking roughly the same amount of fluid or water weight you lose through sweat.

You don't have to, necessarily, have a perfect match. I mean, we, our goal is to try to keep somebody within, not dehydrated in more than 2% of their, their body weight.

It sounds straightforward⁴, stay less than 2% dehydrated. But how in practice can you tell? Douglas Casa is an athletic⁵ trainer and researcher at the University of Connecticut. He's got one strategy. We caught up with him yesterday morning at 6am just before his morning run.

What I'm gonna do is weighing myself, I'm new before I go running.

With an accurate scale, he'll be able to calculate exactly how much water weight he sweats out during his run.

Stepping onto the scale and my pre-weight right now is 63.3 kilograms.

Roughly 140 pounds. With that Casa was out his front door for an-hour-long workout. The focus on tracking dehydration stems in part from concern over a condition known as hyponatremia. This is when someone drinks so much fluid that concentrations of sodium in the blood drop off and the body can't function properly. A study published in the New England Journal of Medicine last year, tracked 488 runners who completed the Boston Marathon, and found 13% of them had dangerously low blood salt levels, twice as many women as men were at risk. Louise Maharam is a sports physician in New York, who chairs the International Marathon Medical Directors Association, he says the first symptoms runners may notice is a little swelling⁶ in the hands.

They can't get their rings off, then they may get nausea⁷, vomiting⁸, and may get dizzy, they may not remember where they are.

Most runners restore salt to normal levels by eating just one meal after a run and never need medical attention, but with a spate⁹ of reported cases of hyponatremia, Maharam's group has a new simple guideline for hydrating. It's contrary to the old advice that runners should drink as much as they can stomach to prevent dehydration.

The new research's shown that the body is a remarkable¹⁰ machine that actually tells you via a thirst when you need fluid.

In other words, drink only when you feel thirsty. For the more performance-oriented runners, Douglas Casa's method is certainly more exacting¹¹. After running one hour and drinking one liter of fluid, Casa hops¹² on the scale a second time.

I'll do kilogram test again; it is 63.0.

So Casa's lost just 3/10 of a kilogram, meaning that he successfully drank enough during his run to replace most of what he lost. Casa says there is no need to weigh every time after a handful of calculations taken under a variety of conditions. Runners get a sense of how much to drink to keep a steady weight.

【WORLD BANK】
hyponatremia
低钠血症

1 dehydration   

n.脱水，干燥

参考例句：

• He died from severe dehydration.他死于严重脱水。
• The eyes are often retracted from dehydration.眼睛常因脱水而凹陷。

2 dilute   

vt.稀释，冲淡；adj.稀释的，冲淡的

参考例句：

• The water will dilute the wine.水能使酒变淡。
• Zinc displaces the hydrogen of dilute acids.锌置换了稀酸中的氢。

3 sodium   

n.（化）钠

参考例句：

• Out over the town the sodium lights were lit.在外面，全城的钠光灯都亮了。
• Common salt is a compound of sodium and chlorine.食盐是钠和氯的复合物。

4 straightforward   

adj.正直的，坦率的；易懂的，简单的

参考例句：

• A straightforward talk is better than a flowery speech.巧言不如直说。
• I must insist on your giving me a straightforward answer.我一定要你给我一个直截了当的回答。

5 athletic   

adj.擅长运动的，强健的；活跃的，体格健壮的

参考例句：

• This area has been marked off for athletic practice.这块地方被划出来供体育训练之用。
• He is an athletic star.他是一个运动明星。

6 swelling   

n.肿胀

参考例句：

• Use ice to reduce the swelling. 用冰敷消肿。
• There is a marked swelling of the lymph nodes. 淋巴结处有明显的肿块。

7 nausea   

n.作呕，恶心；极端的憎恶(或厌恶)

参考例句：

• Early pregnancy is often accompanied by nausea.怀孕期常有恶心的现象。
• He experienced nausea after eating octopus.吃了章鱼后他感到恶心。

8 vomiting   

吐

参考例句：

• Symptoms include diarrhoea and vomiting. 症状有腹泻和呕吐。
• Especially when I feel seasick, I can't stand watching someone else vomiting." 尤其晕船的时候，看不得人家呕。”

9 spate   

n.泛滥，洪水，突然的一阵

参考例句：

• Police are investigating a spate of burglaries in the area.警察正在调查这一地区发生的大量盗窃案。
• Refugees crossed the border in full spate.难民大量地越过了边境。

10 remarkable   

adj.显著的，异常的，非凡的，值得注意的

参考例句：

• She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
• These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。

11 exacting   

adj.苛求的，要求严格的

参考例句：

• He must remember the letters and symbols with exacting precision.他必须以严格的精度记住每个字母和符号。
• The public has been more exacting in its demands as time has passed.随着时间的推移，公众的要求更趋严格。

12 hops   

跳上[下]( hop的第三人称单数 )； 单足蹦跳； 齐足（或双足）跳行； 摘葎草花

参考例句：

• The sparrow crossed the lawn in a series of hops. 那麻雀一蹦一跳地穿过草坪。
• It is brewed from malt and hops. 它用麦精和蛇麻草酿成。