站起来,更健康

One lesson I’ve learned while writing about fitness is that few things 1)impinge on an active life as much as writing about fitness does—all that time spent hunched before a computer or puzzling over scientific journals; the countless hours of fruitless, seated 2)procrastination. While writing about the benefits of exercise, my muscles inevitably 3)slackened. Fat seeped 4)insidiously into my blood, liver, and 5)ventricles. Stupor 6)infiltrated my brain.

We all know by now that being inactive is unhealthy. But far too many of us think that being inactive is something that happens to other people.

However, studies of daily movement patterns show that your typical modern exerciser—even someone who runs—subsequently sits for hours after exercising. Oddly enough, those that do exercise, often move less over all than on days when they don’t work out.

The health consequences are swift, pervasive, and punishing. In a noteworthy, recent experiment conducted by scientists at the University of Massachusetts and other institutions, a group of healthy young men donned a clunky platform shoe with a 4-inch heel on their right foot, leaving the left leg to 7)dangle above the ground. For two days, the men hopped about using 8)crutches. Each man’s left leg never touched the ground. Its muscles didn’t contract. It was fully 9)sedentary.

After two days, the scientists performed muscle 10)biopsies on both legs and found multiple genes now being expressed differently in each man’s legs. Gene activity in the left leg suggested that DNA repair 11)mechanisms had been 12)disrupted, 13)insulin response was dropping, oxidative stress was rising, and 14)metabolic activity within individual muscle cells was slowing after only 48 hours of inactivity.

In similar experiments with lab animals, casts have been placed on their back legs, after which the animals rapidly developed 15)noxious cellular changes throughout their bodies, and not merely in the immobilized muscles. In particular, they produced substantially less of an 16)enzyme that dissolves fat in the bloodstream. As a result, in animals and humans, fat can accumulate and migrate to the heart or liver, potentially leading to cardiac disease and 17)diabetes.

To see the results of such inactivity, scientists with the National Cancer Institute spent eight years following almost 250,000 American adults. The participants answered detailed questions about how much time they spent commuting, watching TV, sitting before a computer and exercising, as well as about their general health. At the start of the study, none suffered from heart disease, cancer or diabetes.

But after eight years, many were ill and quite a few had died. The sick and 18)deceased were in most cases the most sedentary. Those who watched TV for seven or more hours a day proved to have a much higher risk of premature death than those who sat in front of the television less often.

Exercise only slightly lessened the health risks of sitting. People in the study who exercised for seven hours or more a week but spent at least seven hours a day in front of the television were more likely to die prematurely than the small group who worked out seven hours a week and watched less than an hour of TV a day.

If those numbers seem abstract, consider a blunt new Australian study. In the study, researchers determined that watching an hour of television can snip 22 minutes from someone’s life. If an average man watched no TV in hislife, the investigators

concluded that his life span might be 1.8 years longer. A TV-less woman might live for a year and half longer than if she was a regular TV viewer.

So I canceled our cable, leaving my 14-year-old son 19)staggered. I’d deprived him of his favorite shows on the Food Network, a channel that, combined with sitting, explains much about the American waistline.

I also conduct more of my daily business upright. In an inspiring study in Diabetes Care, scientists at the Baker IDI Heart and Diabetes Institute in Melbourne, Australia, had 19 adults sit completely still for seven hours or, on a separate day, rise every 20 minutes and walk leisurely on a treadmill for two minutes. On another day, they had the volunteers jog gently during their two-minute breaks.

When the volunteers remained stationary for the full seven hours, their blood sugar spiked and insulin levels were 20)out of whack. But when they broke up the hours with movement, even that short two-minute stroll, their blood sugar levels remained stable. Interestingly, the jogging didn’t improve blood sugar regulation any more than standing and walking did. What was important, the scientists concluded, was simply breaking up the long, 21)interminable hours of sitting.

Equally beguiling, at least for me, since I’m shallow, were results from experiments at the University of Massachusetts showing that when volunteers stood all day—nothing else; no walking or jogging; just standing—they burned hundreds more calories than when they sat for the same period of time.

So every 20 minutes or so, I now rise. I don’t have a desk treadmill; my office is too small, and my budget too slim. But I prop my papers on a music stand and read standing up. I prowl my office while I talk on the phone.

I run for three or four miles most days, too, and grunt through 20 push-ups most mornings. There are health and fitness benefits from endurance and weight training that standing up can’t match. In particular, 22)aerobic workouts have been shown to improve brainpower, and I shudder to imagine the state of my memory if I didn’t run. But I’m not planning any marathons. I want foundational health. I want my insulin levels in check and my fat-fighting enzymes robust. I have plans for those extra 18 months of life span that not sitting might provide.

在埋首撰写关于健美瘦身文章的时候，我明白到了一个道理：没什么比伏案撰写健美瘦身文章本身对我的健康造成更坏的影响了——整天在电脑前弓背埋首，又或是对着各种科学刊物苦思冥想，还有长时间呆坐一角拖沓做事又苦无成果。我一方面撰文讲述锻炼的好处，另一方面，自己的肌肉却无可避免地变得松弛。体内的脂肪正悄悄地渗入我的血液、肝脏和心室。我的头脑也渐渐感到昏昏沉沉。

现在，人人都知道缺乏活动有害健康，然而更多的人则以为，缺乏活动这种情况只发生在他人的身上。

然而，不少关于日常运动模式的研究表明，如今，典型肯花时间做运动的人——连那些爱跑步的人——都会在运动完后久坐好几个小时。而最奇怪的是，那些经常做运动的人，在没安排锻炼的日子里，常常更久坐怠动。

对健康的不良后果常常来得快，范围广，折腾人。由马萨诸塞州大学的科学家们会同其他研究机构近期进行的一项实验，值得引起我们的注意。研究人员让一群身体健康的年轻男子右脚穿上脚跟有四英寸高的笨重厚底鞋，而左脚则悬空。在接下来的两天里，这些人只能借助拐杖，跳着走动。所有人的左脚在实验期间都没碰过地面。左腿肌肉也就没有收缩，完全保持在静坐时脚的那种状态。

两天后，科学家们对他们双腿的肌肉进行了活组织切片检查，发现每个人双腿的多种基因已经表现出差异：左腿的基因活动显示，DNA的修复机制已经发生中断，胰岛素反应正在下降，氧化应激正在上升，在经过48小时的静止活动后，肌细胞的新陈代谢活动变慢了。

在实验室的动物身上做的类似实验中，接受实验的动物后腿被套上铸件，很快，它们的整个身体内就产生出有害细胞，而不仅仅是在不活动的后腿肌肉内。特别是，一种能分解血液中脂肪的酶的分泌水平出现大幅下降。最终，动物和人体内的脂肪不断积累，并转移到心脏或者肝脏，进而引发心脏病和糖尿病。

为了解身体缺乏活动会造成的后果，科学家们与美国癌症研究所联手，耗时八年，对近二十五万名美国成年人进行了跟踪调查。每个参与者都需要详细回答一系列问题，如花多少时间通勤、看电视、使用电脑和锻炼，以及他们健康状况等问题。这项调查开始时，所有参与者都未患有心脏病、癌症或者糖尿病。

但八年后，很多参与者患上疾病，不少人还离世了。而患病者与死亡者同时也多是那些久坐的人。数据显示， 那些每天看电视7小时或者以上的研究对象，比起那些不常端坐电视机前的，早逝风险要高得多。

锻炼只能轻微降低久坐带来的健康风险。在此项跟踪调查中，那些每周花7小时或以上进行锻炼，但每天又会在电视机前花上至少7小时的人，比起那一小群每周运动7小时而每天看电视不到一小时的人，早逝的风险来得更高。

如果这些数字太过抽象，来看看澳大利亚的一项直言不讳的最新研究。在这项研究中，研究人员发现：每看一小时电视，会缩短人的寿命22分钟。调查人员得出结论：一个普通成年男性，如果在其成年生活中不看电视，其寿命可能会延长1.8年。而不常看电视的女性比起那些女“电视迷”来说，可能会多活上1.5年。

于是，我停掉了家里的有线电视服务——这让我14岁的儿子深感震惊。我的做法让他再也看不到食物频道上他最爱的节目了。这个频道以吃吃喝喝为主题，再加上久坐不动盯着电视，美国人的肥胖问题可见一斑。

同时，在平时工作时，我也尽量多站立。在《糖尿病护理》杂志上的一篇振奋人心的研究报告中，澳大利亚墨尔本大学的贝克国际心脏及糖尿病研究所的科学家们先让19名成年人完全静坐7个小时；改天让他们每坐20分钟就起来在跑步机上随意走上两分钟；还有一天，让受试者每坐20分钟后，在跑步机上慢跑两分钟。

当受试者一动不动地坐上7个小时后，他们的血糖水平飙升，胰岛素水平也发生异常。但当他们在7小时之中穿插运动，即使只是短短的两分钟，血糖水平也保持了稳定。有意思的是，在这两分钟里进行慢跑，比起站立或者散步两分钟，血糖水平并未出现差异。科学家们得出结论：重要的只是将长时间的久坐分割开来。

同样令人欣喜的是——至少对我这种肤浅的人来说吧，马萨诸塞州大学的实验结果表明，当受试者站上一整天——什么也不干，不走动也不慢跑，就这么站着，比起坐上一整天，要多消耗好几百卡路里的热量。

所以现在，我每坐20分钟左右，就会起身活动一下。我没有跑步机；我的办公室很小，我的预算不多。但我会把各种资料放在乐谱架上，站着来读。我打电话的时候，就在办公室来回走动。

大部分时间，我每天也会跑上三四英里，多数早上都会做上二十个俯卧撑。耐力和重力训练对健康和瘦身的益处，是站立所无法比拟的。而有氧训练已经表明对增强大脑功能特别有益。想到如果没有进行过跑步锻炼，我的记忆力会是多么糟糕，我就心有余悸。当然，我不准备去跑马拉松。我只需要保持基本的健康而已。我希望自己的胰岛素水平保持正常，希望那些对抗脂肪的酶也能维持较高的水平。为了多活那从摒弃久坐而获得的18个月，我已做足了功课。