一天运动多久算健康？可能比你想的短

People seeking to stay healthy can get their exercise in small increments of just a few minutes at a time, according to new guidelines issued by the American government that again encourage a largely sedentary nation to start moving.
美国政府新发布了一份指南，希望鼓励这个久坐不动的国家多动一动；而根据这份新指南，那些想保持健康的人现在每次只需运动小几分钟就可以了。

The guidance from a committee appointed by the Department of Health and Human Services of America does away with the official government position that physical activity should occur in sessions of at least 10 minutes.
这份指南来自美国的健康与人类服务部指派的一个委员会，它表达的意见和政府的官方说法不同，后者认为运动应该至少持续10分钟。

"Current evidence shows that the total volume of moderate-to-vigorous physical activity is related to many health benefits; bouts of a prescribed duration are not essential," the committee of health experts wrote.
委员会的健康专家写到：“目前的证据显示，只要中等至较大强度运动的总时长足够，就能带来很多健康益处，而单次运动的时长则并不是很重要。”

"Sit less, move more. Whatever you do, it really all counts," Brett P. Giroir, assistant secretary for health at HHS, said in an interview.
健康与人类服务部的助理健康书记官Brett P. Giroir说：“少坐一点，多动一点。不管你怎么动，真的都有用。”

Thomas Allison, director of sports and exercise cardiology at the Mayo Clinic in Rochester, Minnesota, said short bouts of exercise are valuable to break up long stretches of sitting.
明尼苏达州罗切斯特市梅约诊所的运动及运动心脏病学主管Thomas Allison说：短时间的小运动是很有用的，它们可以打断你的久坐行为。

But research shows that multiple short sessions should involve similar energy expenditure to have the same impact as one longer session, or additional time moving will be needed, he said.
不过他还说，根据研究显示，短时间的运动如果想达到和正常锻炼相同的功效，需要消耗和正常锻炼差不多的总能量，要不然你就要继续多做一些运动。

For adults to stay healthy, the new guidelines call for 150 to 300 minutes of moderate-intensity exercise or 75 to 150 minutes of vigorous-intensity physical activity each week, along with at least two days a week of muscle-strengthening exercises.
新的指南说，对于那些想保持健康的成年人，每周需要150至300分钟的中等强度锻炼，或者75至150分钟的较大强度锻炼，另外每周还需要用两天来进行肌肉强化运动。

The guidelines cite walking briskly at 3.9 to 6.4 kilometres per hour, playing volleyball or raking leaves as moderate-intensity activity.
指南提到的中等强度活动包括：以3.9-6.4千米/小时的速度走路、玩排球或者扫落叶。

Vigorous-intensity exercise includes jogging or running, carrying heavy groceries or taking a strenuous fitness class, the panel said.
较大强度的活动包括：慢跑、快跑、拎较重的杂货或者上费劲的私教课。

Some workouts, such as swimming and cycling, can fall into either category, depending on the effort expended.
还有一些运动，比如游泳和骑单车，根据你花的力气不同可以被归为不同的类别。