发表在《自然》上的一篇文章指出，一项新的研究表明，穿着跑鞋跑步其实对身体并不好，赤脚跑步反而可以避免奔跑带来的损伤。

This is the VOA Special English Health Report.

Two new studies suggest that modern running shoes could increase the risk of injuries to runners.

One study involved sixty-eight healthy young women and men who ran at least twenty-four kilometers a week. The runners were observed on a treadmill machine. Sometimes they wore running shoes. Other times they ran barefoot.

Researchers from the JKM Technologies company in Virginia, the University of Virginia and the University of Colorado did the study.

They found that running shoes create more stress that could damage knees, hips and ankle joints than running barefoot. They observed that the effect was even greater than the effect reported earlier for walking in high heels.

The study appeared in the official scientific journal of the American Academy of Physical Medicine.

The other study appeared in the journal Nature. It compared runners in the United States and Kenya. The researchers were from Harvard University in Massachusetts, Moi University in Kenya and the University of Glasgow in Scotland.

They divided the runners into three groups. One group had always run shoeless. Another group had always run with shoes. And the third group had changed to shoeless running.

Runners who wear shoes usually come down heel first. That puts great force on the back of the foot. But the study found that barefoot runners generally land on the front or middle of their foot. That way they ease into their landing and avoid striking their heel.

Harvard's Daniel Lieberman led the study. He says the way most running shoes are designed may explain why those who wear them land on their heels. The heel of the shoe is bigger and heavier than other parts of the shoe, so it would seem more likely to come down first. Also, the heel generally has thick material under it to soften landings.

But the researchers do not suggest that runners immediately start running barefoot. They say it takes some training. And there can be risks, like running when your feet are too cold to feel if you get injured.

The study was partly supported by Vibram, which makes a kind of footwear that it says is like running barefoot. The findings have gotten a lot of attention. But the researchers say there are many problems in the way the press has reported on their paper. So they have tried to explain their findings on a Harvard Web site. For a link, go to en8848.com.

And that's the VOA Special English Health Report, written by Caty Weaver. I'm Steve Ember.

一位长跑发烧友，哈佛大学的人类进化生物学家丹尼尔·雷柏尔曼决定寻找这个问题的答案。他和同事们调查了200位穿鞋和光脚的长跑者，这些长跑者来自美国和以非凡毅力着称的肯尼亚裂谷省。这些调查对象为他们提供了一系列与鞋有关亲身经历，类型包括从小就穿鞋跑步的成年人，从小光脚跑长大才穿鞋的人，以及到现在都光脚跑的人。雷柏尔曼的团队对这些人做了一个实验，每一类型都分为两组--穿鞋者和光脚者。穿鞋的长跑者使用自己的跑鞋或者是爱世克斯防震系列型号为GEL-Cumulus 10s的跑鞋。在这个实验里，他们测量长跑者的步法以及对身体的影响。

很快，研究者发现了不同。穿鞋的用脚后跟落地，而光脚的用大脚趾或者扁平足着地。赤脚者的跑步方式使弯曲的足弓、踝关节和膝盖上生出更多的纹路，同时需要更多步伐和小腿肚肌肉，减弱了对身体的冲击，长跑之旅变得更加自在。在足部与地面冲撞的一瞬间，光脚者感受到其自身体重0.5到0.7倍的冲击力，而穿鞋者的脚后跟感受到其体重的1.5到两倍，是光脚者的三到四倍。

雷柏尔曼非常惊讶，"过去我常常认为赤脚跑很疯狂而且很疼。"然而，即将发布在《自然》的这项成果显示，光脚跑可以降低疼痛和关节磨损发生的可能性。许多长跑引起的伤害，诸如外胫夹和足底筋膜炎都是压力和冲击造成的。