Sitting For More Than Three Hours A Day Cuts Life Expectancy
一
項最新研究表明，每天坐三個小時以上可減少兩年的預期壽命，就算保持良好的運動習慣、禁絕吸煙等不良嗜好也無助於改變這一結果。《英國醫學雜志》在線版(BMJ Open)將於周二發表該項研究。
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研究人員表示，如果你總是坐著總是不動的話，就可能在血糖控制上遇到麻煩。
這項綜合分析報告出爐之前的兩年，澳大利亞的研究人員發現，那些聲稱自己每天看電視超過四個小時的人因任何一種原因死亡的可能性都比那些聲稱自己每天看電視不到兩個小時的人高出46%。而且，那些每天看電視超過四小時的人死於心血管疾病的可能性要高出80%。
該 項研究的項目主管之一卡茲馬茲克(Peter T. Katzmarzyk)說，對於那些久坐成習的人，我們給他們的建議不僅僅應該是每天運動30分鐘。卡茲馬茲克是路易斯安那州首府巴吞魯日市(Baton Rouge)彭寧頓生物醫學研究中心(Pennington Biomedical Research Center)的一名人口學教授。
卡茲馬茲克解釋說，有一些人的確可以做到每天運動30分鐘，但如果在每天其余的20個小時裡他都不動或是坐著，那麼他仍有預期壽命縮短的風險。
不過，盡管將久坐與各種疾病聯系起來的証據汗牛充棟，對很多人來說花點時間邁開雙腿仍然非常困難，尤其是對需要伏案工作的人來說。
卡茲馬茲克說，盡可能想辦法站著；通常來說，如果你是在打電話的話，你就可以站著講話；不必給同一個辦公室的人發電子郵件，站起來走過去，當面跟他們講。
不過，卡茲馬茲克博士還補充道，站立並不是用來代替運動的，而是用來代替久坐的。他說，一些研究表明，人在坐著的時候，腿部的肌肉是完全鬆弛的，如果你總是坐著總是不動的話，就可能在血糖控制上遇到麻煩。
研 究人員在確定久坐這一行為的流行程度時利用了美國國家健康與營養調查(National Health and Nutrition Examination Survey)提供的2009年至2010年間的久坐習慣數據。目前可得的最新電視觀看數據是2005年到2006年間的數據。
研究人員在審視五個基礎研究的過程中剔除了已經患病因而更有可能久坐的病人的數據。
卡茲馬茲克說，該項分析的局限之一就是完全依賴自我報告，而人們往往傾向於低估自己坐著的時間。
這項研究為一系列聲稱久坐的生活方式會導致一系列風險的研究提供了支持。
去年，科學家發現，與那些從未從事過需要久坐工作的人相比，那些坐著工作10年的人，或是工作中不需要消耗太多能量的人，罹患結腸癌的風險高出一倍，罹患直腸癌的風險高出44%。
今年3月份，科學家發現罹患癌症的幾率與肥胖程度和缺乏體育運動有關，比如從1999年到2008年間，腎癌、胰腺癌、食道癌和子宮癌的發病率每年都在增加。
Sitting down for more than three hours a day can shave a person's life expectancy by two years, even if he or she is physically active and refrains from dangerous habits like smoking, according to a study to be published on Tuesday in the online journal BMJ Open.
Watching TV for more than two hours a day can exacerbate that problem, decreasing life expectancy by another 1.4 years, said the report, which analyzed five underlying studies of nearly 167,000 people over a range of four to 14 years.
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.
'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 Baton Rouge, La.
'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.'
But while the evidence linking sedentary behavior to various illnesses is mounting, it remains difficult for many people to find time to get on their feet, especially if they work desk jobs.
'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.'
However, Dr. Katzmarzyk added, standing 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 glucose.'
Researchers determined 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.
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.
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.
The study bolsters an emerging body of research that points to a number of dangers associated with leading a sedentary lifestyle.
Last year, scientists found that people who worked 10 years in sedentary jobs, or jobs that don't require a lot of energy expenditure, had twice the risk of colon cancer and a 44% increased risk of rectal cancer, compared with people who had never worked sedentary jobs.
And in March, scientists found that the rate of cancers linked to obesity and lack of physical activity, such as cancers of the kidney, pancreas, lower esophagus and uterus, rose every year from 1999 through 2008.
ANDREW SEIDMAN
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