Here's a new warning from health experts: Sitting is deadly.

Scientists are increasingly warning that sitting for prolonged periods - even if you also exercise regularly - could be bad for your health. And it doesn't matter where the sitting takes place - at the office, at school, in the car or before a computer or TV - just the overall number of hours it occurs.

Research is preliminary, but several studies suggest people who spend most of their days sitting are more likely to be fat, have a heart attack or even die.

In an editorial published this week in the British Journal of Sports Medicine, Elin Ekblom-Bak of the Swedish School of Sport and Health Sciences suggested that authorities rethink how they define physical activity to highlight the dangers of sitting.

While health officials have issued guidelines recommending minimum amounts of physical activity, they haven't suggested people try to limit how much time they spend in a seated position.

Even for people who exercise, spending long stretches of time sitting at a desk is still harmful. Tim Armstrong, a physical activity expert at the World Health Organization, said people who exercise every day - but still spend a lot of time sitting - might get more benefit if that exercise were spread across the day, rather than in a single bout.

That wasn't welcome news for Aytekin Can, 31, who works at a London financial company, and spends most of his days sitting in front of a computer. Several evenings a week, Can also teaches jiu jitsu, a Japanese martial art involving wrestling, and also does Thai boxing.

Still, in a study published last year that tracked more than 17,000 Canadians for about a dozen years, researchers found people who sat more had a higher death risk, independently of whether or not they exercised.

Figures from a U.S. survey in 2003-2004 found Americans spend more than half their time sitting, from working at their desks to sitting in cars.

Experts said more research is needed to figure out just how much sitting is dangerous, and what might be possible to offset those effects.

来自健康学家的新提醒：久坐致命。

科学家开始越来越多地提醒久坐的人们--就算经常运动--久坐也对身体健康不利。不管坐在什么地方--办公室也好，学校也好，车上或是电脑电视前--总而言之，只要久坐，都对身体健康不利。

虽然这只是个初步的研究，但是多份报告表明大部分时间都坐着的人更可能肥胖，患心脏病甚至死亡。

本周英国体育医学杂志的一篇社论中，瑞典体育学院的 Elin Ekblom-Bak 建议专家们重新定义体育运动的含义以强调坐着的危害性。

然而卫生部的官员却提出了最小体育运动量一说，他们不赞同一个坐姿需要限制在多长时间内的说法。

即使是常运动的人，在桌前久坐不动也对健康有害。Tim Armstrong,世界卫生组织的一位体育运动专家说，每天运动即使久坐，如果以运动贯穿全天，而不只是一时兴起才运动一下的人，可能可以从中获利。

这对于现年31岁，在伦敦金融公司工作的Aytekin Can来说可不是个愉快的消息，要知道他的大部分时间都得坐在电脑前。一个星期里有好几个晚上，Can还要教授柔术，一种融合了摔跤的日本武术，同时他还练习泰拳。

而研究人员对17,000多名加拿大人进行了长达10多年的跟踪调查，并于去年公布了研究报告，结果表明久坐的人死亡率更高，这与他们是否锻练无关。

一份来自美国2003年到2004年间的调查数据显示，美国人从坐在桌前办公到坐在车里，多半时间都是坐着的。

另有专家指出这需要更多的调查才能知道坐多久才是造成危害的量，还有就是如何才能消除久坐的危害。