定时训练(16)
专题特训(阅读理解——推理判断)
体裁：说明文 话题：健康 时间：5分钟
Most of us have years of sitting experience，consider ourselves quite good at it.But unfortunately，the sitting can lead to poor circulation and all kinds of aches and pains.
We're not using much energy when we're sitting still.A person with a desk job may burn 300 calories a day at work，but that same person might burn 2，300 calories a day in a job that requires considerable physical effort.
Sitting at your desk for hours can increase your chances of getting diabetes，heart disease or even an early grave.Every hour of TV that people watch while sitting cuts about 22 minutes from their life span.
How can this happen? Not only does sitting decrease calorie burning，but it can prevent the production of lipoprotein lipase(脂肪蛋白酶)，which is essential for turning bad cholesterol(胆固醇)into good.Sitting can also make sugar not easy to change into useful energy.All these are thought to connect with heart disease and diabetes.
Is there any hope? A treadmill (跑步机)called active sitting can help people to adjust their gestures of sitting.There are simpler steps to take too—merely increasing the number of steps you take during the day.You can improve your glucose metabolism(葡萄糖代谢) with a two－minute walk every 20 minutes.Many people have done some of their best work while sitting at their desks.But many others have achieved remarkable success while standing up on the job，including Winston Churchill，Charles Dickens，Benjamin Franklin，Ernest Hemingway and Mark Twain.And then there was Einstein，Levine notes: “He was riding a bike when he came up with e＝mc2.”
