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.
【視聽版科學(xué)小組榮譽(yù)出品】
tuckers out in motion recruited logged miles strides
為何小孩走不了遠(yuǎn)路 如果你有過帶著小孩逛超市的經(jīng)驗(yàn),你就會知道走路對小孩子來說是種折磨。近來科學(xué)家們得到答案了。這項(xiàng)結(jié)果發(fā)表在《實(shí)驗(yàn)生物學(xué)期刊》上。動物體積越大,它們的體重每克消耗的能量比體積小的要少得多,即使在休息的時候也是如此。它們在活動中呢?研究人員招募了不同年齡和體型的步行者,從三尺高的幼兒園小孩到六尺高的成人。受試者記錄跑步機(jī)上的里程數(shù)時,科學(xué)家們測量他們的步幅和新陳代謝。他們發(fā)現(xiàn)不管這些人身高是怎樣的,他們的走路方式差不多一致。如果你將一個5歲的小孩按比例拉到六尺半那么高,這個巨大的小孩跑起來跟一個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樣的。也就是說體積大點(diǎn)的人也不會因?yàn)殚e逛而消耗的能量就少一點(diǎn)。正如你懷疑的一樣,他們消耗更少的能量是因?yàn)樗麄冇酶俚牟阶泳湍茏咭粯舆h(yuǎn)的路。這也意味著對于有些人來說在公園里走路并不就是散步。