If people run more in New York City, that can push their socially connected counterparts in San Diego to run more as well.

据克里斯托弗·因塔利亚塔（Christopher Intagliata）报道，如果在纽约的人跑步的频率更高，那么这就可以促使他们在圣地亚哥社交圈子里的人也跑得更多。

撰文/播音：克里斯托弗·因塔利亚塔(Christopher Intagliata)

翻译：路识宇

审校：杨枭

If your friends are happy—turns out you're more likely to be happy too. If your friends are overweight, that too ups the odds you'll pack on pounds. Those effects have been shown in studies. And now researchers have identified another seemingly contagious quality: exercise.

如果你的朋友很开心，那么你也更有可能很开心。如果你的朋友超重，那么你也有很大的几率会变重。已经有研究证实了这些效应。现在研究人员已经确定了另一个看起来具有传染性的特征：锻炼。

The investigators analyzed the running activity of more than a million individuals worldwide who used an exercise tracking device for five years. And they used weather patterns as a way to randomly examine different parts of that global network.

调查人员分析了全球超过一百万个使用运动跟踪装置的人五年内的跑步活动情况。他们利用天气模式来随机检测全球不同地点的运动状况。

"If it happens to be a really nice day out, sunny and not too hot, not too cool, that will induce people to run more.” Sinan Aral, a computational social scientist at MIT. “If it's a rainy day and cold, that will induce people to stay in more on average." 

麻省理工学院的计算社会科学家锡南·阿拉尔（Sinan Aral）说，“如果正好是一个外出的好天气，阳光明媚，不是很热，也不是太冷，更多的人会选择外出跑步。”如果这是一个阴冷的雨天，那人们更倾向于留在家里。”

And since cities have different weather patterns, he says, this natural experiment allowed them to ask: Does a rainy day in New York affect running in San Diego? "If the weather in New York causes changes in the running behavior in San Diego, it can really only be happening thru peer influences of the friends who live between New York and San Diego."

他表示，而且由于城市天气状况不同，这个自然实验让他们产生了疑问：纽约的雨天是否会影响圣地亚哥的跑步情况？”如果纽约的天气导致了圣地亚哥的跑步运动发生变化，那么对此唯一的解释只能是因为住在纽约和圣地亚哥的朋友之间的互相影响。”

And that is exactly what he and his colleague saw: that the behavior of one city's runners could indeed affect the behavior of runners in another socially connected city. The study is in the journal Nature Communications. [Sinan Aral & Christos Nicolaides, Exercise contagion in a global social network]

这也正是他和他的同事观察到的：一个城市的跑步者的行为的确会影响到另一个和他们有社交联系的城市的跑步者的行为。该研究被刊登在“Nature Communication”杂志上。 [Sinan Aral＆Christos Nicolaides，全球社会网络中的运动传染病](注: 作者为: Sinan Aral＆Christos Nicolaides， 文章标题为: Exercise contagion in a global social network)

A few caveats: women tended to be influenced more by the female runners in their networks. And less active runners tended to influence more active runners to run more, but not so much the other way around. Still, this could be valuable intel for health professionals. "We have to start thinking about consumers and citizens as networked consumers and networked citizens. Where they are influenced by and influence their social network in very strong and dynamic ways, that will change the way a particular intervention succeeds or fails."

有几点需要注意的是：女性更容易受到社交圈子里女性跑步者的影响。而且不怎么活跃的跑步者容易影响活跃的跑步者使他们跑得更多，但是这种影响反向却不一定成立。不过，这对于健康专家们来说可能是很有价值的信息。“我们得开始把消费者和公民看作网络消费者和网络公民。在社交网络中，他们彼此有强烈的动态影响，这会改变特定干预方式的成败。”

In other words—if your prescription is more exercise? The doctors might want to write a prescription for your friends and family, too.

换句话说—如果医生给你开了个多运动运动的处方？医生可能也会想给你朋友和家人也开张这样的处方啦。

—Christopher Intagliata