科学60秒:为何小孩走不了远路
来源：沪江听写酷
2011-06-13 08:30
If you’ve ever had to pick up and carry a tired child through the mall, you know that walking sometimes [--1--] the toddlers. Now scientists think they know why. The results appear in the Journal of Experimental Biology.
Larger animals tend to use less energy per gram of body mass than smaller ones do, even at rest. But what happens when they’re [--2--]? Researchers [--3--] walkers of different ages and sizes, from a three-foot-tall kindergartner to a six-foot adult. While the subjects [--4--] on the treadmill, the scientists measured their stride and metabolism.
And they found that people pretty much walk the same way, regardless of their stature. If you scaled a five-year-old up to be six-and-a-half feet tall, the giant child would lope along just like a similarly sized adult.
What’s more, walkers of all heights use the same amount of energy per step. That means that big people don’t conserve energy by strolling in a more economical style. They expend less energy because—just as you may have always suspected—they simply need fewer [--5--] to cover the same ground. Which means that for some people a walk in the park ain’t necessarily a walk in the park.
【视听版科学小组荣誉出品】
Larger animals tend to use less energy per gram of body mass than smaller ones do, even at rest. But what happens when they’re [--2--]? Researchers [--3--] walkers of different ages and sizes, from a three-foot-tall kindergartner to a six-foot adult. While the subjects [--4--] on the treadmill, the scientists measured their stride and metabolism.
And they found that people pretty much walk the same way, regardless of their stature. If you scaled a five-year-old up to be six-and-a-half feet tall, the giant child would lope along just like a similarly sized adult.
What’s more, walkers of all heights use the same amount of energy per step. That means that big people don’t conserve energy by strolling in a more economical style. They expend less energy because—just as you may have always suspected—they simply need fewer [--5--] to cover the same ground. Which means that for some people a walk in the park ain’t necessarily a walk in the park.
【视听版科学小组荣誉出品】
tuckers out
in motion
recruited
logged miles
strides
为何小孩走不了远路
如果你有过带着小孩逛超市的经验，你就会知道走路对小孩子来说是种折磨。近来科学家们得到答案了。这项结果发表在《实验生物学期刊》上。动物体积越大，它们的体重每克消耗的能量比体积小的要少得多，即使在休息的时候也是如此。它们在活动中呢？研究人员招募了不同年龄和体型的步行者，从三尺高的幼儿园小孩到六尺高的成人。受试者记录跑步机上的里程数时，科学家们测量他们的步幅和新陈代谢。他们发现不管这些人身高是怎样的，他们的走路方式差不多一致。如果你将一个5岁的小孩按比例拉到六尺半那么高，这个巨大的小孩跑起来跟一个等尺寸的成年人也差不多。另外，相同高度的人每一步步行所消耗的能量是一样的。也就是说体积大点的人也不会因为闲逛而消耗的能量就少一点。正如你怀疑的一样，他们消耗更少的能量是因为他们用更少的步子就能走一样远的路。这也意味着对于有些人来说在公园里走路并不就是散步。
