Sitting down for more than three hours a day can shave a person's life expectancy¹ by two years, even if he or she is physically² active and refrains from dangerous habits like smoking, according to a study to be published on Tuesday in the online journal BMJ Open.

一项最新研究表明，每天坐三个小时以上可减少两年的预期寿命，就算保持良好的运动习惯、禁绝吸烟等不良嗜好也无助于改变这一结果。《英国医学杂志》在线版(BMJ Open)将于周二发表该项研究。

Watching TV for more than two hours a day can exacerbate³ that problem, decreasing life expectancy by another 1.4 years, said the report, which analyzed⁴ five underlying⁵ studies of nearly 167,000 people over a range of four to 14 years.

报告称，每天看电视超过两个小时将使问题变得更加严重，进一步减少1.4年的预期寿命。该报告分析了五项基础研究，这五项研究在四年到14年的时间跨度内对167,000名对象进行了调查。

The meta-analysis comes just two years after Australian researchers found that people who said they watched TV for more than four hours a day were 46% more likely to die of any cause than people who said they spent less than two hours a day watching TV. Those watching TV more than four hours a day were also 80% more likely to die of cardiovascular disease.

这项综合分析报告出炉之前的两年，澳大利亚的研究人员发现，那些声称自己每天看电视超过四个小时的人因任何一种原因死亡的可能性都比那些声称自己每天看电视不到两个小时的人高出46%。而且，那些每天看电视超过四小时的人死于心血管疾病的可能性要高出80%。

"Sedentary behavior is something we need to take note of beyond telling people to get 30 minutes of activity a day," said Peter T. Katzmarzyk, one of the lead researchers for the study and a professor of population science at the Pennington Biomedical Research Center in Baton⁶ Rouge⁷, La.

该项研究的项目主管之一卡兹马兹克(Peter T. Katzmarzyk)说，对于那些久坐成习的人，我们给他们的建议不仅仅应该是每天运动30分钟。卡兹马兹克是路易斯安那州首府巴吞鲁日市(Baton Rouge)彭宁顿生物医学研究中心(Pennington Biomedical Research Center)的一名人口学教授。

"We have people who can meet that guideline," explained Dr. Katzmarzyk. "However, if you're sedentary or sitting the other 20 hours a day, you're still going to be at risk for that."

卡兹马兹克解释说，有一些人的确可以做到每天运动30分钟，但如果在每天其余的20个小时里他都不动或是坐着，那么他仍有预期寿命缩短的风险。

But while the evidence linking sedentary behavior to various illnesses is mounting, it remains⁸ difficult for many people to find time to get on their feet, especially if they work desk jobs.

不过，尽管将久坐与各种疾病联系起来的证据汗牛充栋，对很多人来说花点时间迈开双腿仍然非常困难，尤其是对需要伏案工作的人来说。

"Try to stand as much as you can," Dr. Katzmarzyk said. "Typically when you're on the telephone you can stand with speaker phone. Instead of emailing someone in the office, just get up and go talk to them."

卡兹马兹克说，尽可能想办法站着；通常来说，如果你是在打电话的话，你就可以站着讲话；不必给同一个办公室的人发电子邮件，站起来走过去，当面跟他们讲。

However, Dr. Katzmarzyk added, standing⁹ shouldn't be an alternative to exercising, but an alternative to sitting. "Several studies show that when you're sitting, your leg muscles are completely inactive," he said. "When you're sitting and completely inactive, this is when you run into trouble managing blood glucose¹⁰."

不过，卡兹马兹克博士还补充道，站立并不是用来代替运动的，而是用来代替久坐的。他说，一些研究表明，人在坐着的时候，腿部的肌肉是完全松弛的，如果你总是坐着总是不动的话，就可能在血糖控制上遇到麻烦。

Researchers determined¹¹ the prevalence of sedentary behavior by using the National Health and Nutrition Examination Survey, which provided data on sitting habits between 2009 and 2010. The most recent available data on TV viewing was between 2005 and 2006.

研究人员在确定久坐这一行为的流行程度时利用了美国国家健康与营养调查(National Health and Nutrition Examination Survey)提供的2009年至2010年间的久坐习惯数据。目前可得的最新电视观看数据是2005年到2006年间的数据。

When looking at the five underlying studies, the researchers eliminated data on patients with existing diseases and were therefore more likely to be sitting a lot.

研究人员在审视五个基础研究的过程中剔除了已经患病因而更有可能久坐的病人的数据。

One of the analysis's limitations was that it relied on self-reporting, as people tend to underestimate how much sitting they do, Dr. Katzmarzyk said.

卡兹马兹克说，该项分析的局限之一就是完全依赖自我报告，而人们往往倾向于低估自己坐着的时间。

The study bolsters¹² an emerging body of research that points to a number of dangers associated with leading a sedentary lifestyle.

这项研究为一系列声称久坐的生活方式会导致一系列风险的研究提供了支持。

Last year, scientists found that people who worked 10 years in sedentary jobs, or jobs that don't require a lot of energy expenditure¹³, had twice the risk of colon¹⁴ cancer and a 44% increased risk of rectal cancer, compared with people who had never worked sedentary jobs.

去年，科学家发现，与那些从未从事过需要久坐工作的人相比，那些坐着工作10年的人，或是工作中不需要消耗太多能量的人，罹患结肠癌的风险高出一倍，罹患直肠癌的风险高出44%。

And in March, scientists found that the rate of cancers linked to obesity¹⁵ and lack of physical activity, such as cancers of the kidney, pancreas, lower esophagus and uterus, rose every year from 1999 through 2008.

今年3月份，科学家发现罹患癌症的几率与肥胖程度和缺乏体育运动有关，比如从1999年到2008年间，肾癌、胰腺癌、食道癌和子宫癌的发病率每年都在增加。