有一种叫“经济舱综合症”的病，估计很多人第一次听说。如果人在狭窄的空间长时间坐着不动，比如乘坐飞机时，腿一直弯曲着，结果会使腿部后侧静脉的血流速度降低，并在小腿深静脉中形成血凝，如血凝块脱落，顺着血流到达肺部，并在肺部形成栓塞即肺栓塞，可能会引起猝死，这就是“经济舱综合症”：一种久坐不动能致人命的病。据世界卫生组织估计，长途飞行旅客中此危险发生的几率为1/6000，这就意味着1个运载300名乘客的航班，每长途飞行20次就会有1位乘客发生“经济舱综合症”。实际上，专家认为，只要保持一个坐势，腿一直弯曲着，不活动超过4个小时，那么，发生深静脉血栓栓塞即“经济舱综合症”的危险将会明显增加。而现在，坐车的人，长时间坐着工作的人，在电脑前一坐就是半天的人，比乘坐飞机的人要多得多，“经济舱综合症”将会威胁着更多久坐的人。
It seems the more (1)cramped(狭窄的，拥挤的) your airplane seat is, the longer the flight always takes. Some folks handle this situation by just sitting tight(绷紧的) for the entire duration(持续，期间), dreaming of the hour when the plane finally lands and they get to stretch.
That may be adding danger to discomfort, studies have found. The discomfort part you already know about. The danger is that when your body is left in a cramped position for too long, blood clots(血块) can form in your feet and legs. That’s dangerous, because a blood clot that (2)dislodges(移动，逐出) will travel in the blood stream. And that’s nothing to play around with. If it reaches your lungs, it could even kill you!
Now, of course not every hurting leg is indication of a blood clot. For the most part it’s just cramped(抽筋的) muscle. But research conducted at Tripler Army Medical Center in Honolulu showed that a surprising one out of four patients in a study group being treated for blood clots in the lower legs had been on airplanes within the past month. And a (3)whopping(巨大的) eighty-two percent still had symptoms(症候，症状) two weeks after their flight!
The problem is that sitting for four hours or more reduces blood (4)circulation(循环) in the legs, especially if you are cramped up. So, to keep the old juices flowing, and to help lower the chance of blood clots forming during a long flight, get up and walk a little in the aisle(通道，走廊).
注释：
(1)cramped['kræmpt] a.
1.难认的;难懂的
2.患抽筋的
3.狭窄的
Our accommodation is rather cramped. 我们住的地方很挤。
(2)dislodge vt.
1.用力(或设法)移动;逐出[(+from)]
The doctor dislodged the fish bone from her throat.
医生取出哽在她喉中的鱼骨头。 vi.
1.离开住处
(3)whopping a.
1.巨大的;异常的 ad.
1.非常
(4)circulation n.
1.循环,环流;运行[U][S1]
We observed the circulation of blood in frogs.
我们观察了青蛙的血液循环。
2.(货币、消息等的)流通,传播[U]
Many forged notes are in circulation.
许多假钞在流通。
3.(报刊等的)发行量,销售量[S]
This paper has a circulation of more than a million.
这一报纸的发行量达一百多万份。
4.通货 ,货币[U]
