地球人到底能跑多快？

MORE THAN 130 years ago, at the first Olympic Games in Athens, Boston University law student Thomas Burke took his mark at the 100-meter dash not in a standing position, but a crouch—what was then considered an unusual starting stance.

130多年前在雅典举行的第一届奥运会上，波士顿大学法律系的学生Thomas Burke在100米短跑的比赛中，没有采用站立的起跑姿势，而是蹲下了身子——在那时候，这可是个非常不寻常的事儿。

But far more unusual, by today's standards, was his gold-medal winning time of 12 seconds flat.

但以今天的眼光来看，更加不寻常的是，他以12秒整的成绩拿到了那届奥运会的百米金牌。

These days, talented middle schoolers post 100-meter times better than Burke's. In March 2018, 15-year-old Briana Williams, a high school sophomore, set a world age-group record in the event with a time of 11.13 seconds. The record for boys 18-and-under is nearly a second faster still: Set in 2017 by Anthony Schwartz, the 10.15-second time would have won gold at 1980's Summer Games.

现在，稍有点天赋的中学生都能跑得比这个成绩好。2018年3月，15岁的高中二年级学生Briana Williams以11秒13的成绩创造了他这个年龄组的世界纪录。而对于18岁以下年龄组的男选手，成绩还要再快将近1秒：Anthony Schwartz在2017年创造了10秒15的纪录，这个成绩能拿到1980年奥运会的百米金牌。

Today, though, on the world stage, Schwartz wouldn't even podium: In the past 30 years, only three sprinters have medaled at the Olympics with a time slower than 10 seconds. Propelled by more effective training, grippier track surfaces, faster footwear, and, yes, pharmaceuticals, competitors at every level of track and field's premier event have steadily chipped away at the world's best 100-meter times. Jamaican sprinter Usain Bolt holds the current world record: a sprightly 9.58 seconds.

而在今天，Schwartz的成绩甚至不够站上领奖台：在过去30年间，只有3位短跑选手曾经以慢于10秒的成绩获得奥运会的奖牌。在更有效的训练、抓地力更好的跑道、更快的跑鞋，以及……嗯，药物的推动下，每个级别的主要田径赛事中，选手们跑完100米的时间都变得越来越短了。牙买加人博尔特(Usain Bolt)保持着现在的世界纪录：9秒58。

The surprisingly persistent record progression is enough to make anyone ask: When will the fastest people on Earth cease to become any faster? And when they do, what will the fastest time ultimately be?

百米纪录惊人的刷新速度足以让人们开始好奇：什么时候会有人再度打破这个纪录?以及……地球人到底能跑多快?

Depending on how you look at it, the answer to the first question could be "very soon," or "not soon at all." As recently as 2008, the popular perception among people who think about such things was that elite 100-meter runners were approaching the limits of possibility. Then came Bolt, who burst onto the scene at the Beijing Olympics with a record-wrecking time of 9.69 seconds—an anomalous performance, mathematicians thought, that statistical models placed two decades ahead of its time. But the following year, when Bolt broke his record by nine-hundredths of a second, he also broke, categorically, those old models. Today, revised probabilistic estimates project that his record could stand for upwards of two centuries. But who knows how that projection will measure up against reality. As applied mathematician David Sumpter has observed, Bolt singlehandedly demolished our ability to make reliable predictions about the 100-meter dash.

第一个问题的答案取决于看问题的角度，可能是“非常快”，也可能是“早着呢”。就在不久前的2008年，人们还普遍认为当时的顶尖运动员已经接近了人类100米速度的极限。随后博尔特就横空出世了，他在北京奥运会上以9秒69的成绩打破当时的世界纪录——这个成绩让人惊掉了下巴，数学家们甚至认为，他的成绩比统计模型的预计早了整整20年。而在2009年，博尔特又把自己保持的纪录提高了百分之九秒。与纪录一同被打破的还有传统的统计模型。如今，一项修正过的概率推算预测，他的纪录甚至有可能保持两个世纪以上。但鬼才知道这种预测到底在现实面前能有多靠谱。正如应用数学家David Sumpter所言，博尔特单枪匹马就摧毁了我们预测百米短跑纪录的能力。

Which is one reason biomechanists approach the matter somewhat differently than mathematicians. They address the second question by investigating not when Bolt's record might fall, but by how much, based on the bodies of today's fastest sprinters.

这也是生物力学家们和数学家们在处理这个问题时采取不同看法的原因。对于第二个问题，他们考虑的不是什么时候博尔特的纪录会被打破，而是他的纪录会被超过多少。考虑问题的基准则是如今顶尖短跑运动员的身体。

"Once they get rolling, the force they apply becomes a motion-based mechanism, where they use their limbs to throw a punch at the ground," says biomechanist Peter Weyand. As director of the Locomotor Performance Laboratory at Southern Methodist University in Dallas, Weyand invites many of the fastest sprinters on Earth to run in short bursts in front of high-speed, motion-tracking cameras on a bespoke, force-sensing treadmill that makes the thing you trot on at your gym look like a glorified hamster wheel.

“一旦起跑，运动员们就成了一架精密运行的力学机器，用他们的肢体不断地向地面施加动力。”生物理学家Peter Weyand说道。作为南方卫理公会大学(Southern Methodist University)运动性能实验室的主任，Weyand邀请了地球上许多最快的短跑选手，来在定制的力学感应跑步机上短途冲刺。在高速运动追踪摄影机前的，这些运动员就像是轮子中的小仓鼠一样。

Based on his observations, Weyand says the two biggest factors limiting the performance of elite sprinters are how much force they can apply to the ground, and how fast. At current top speeds of around 27 miles per hour, he says elite male sprinters like Usain Bolt put down roughly five times their body weight, in between .085 and 0.09 seconds.

根据他的观测，Weyand说，限制短跑选手们成绩的两个最大因素是他们能给地面施加多大的力量，以及施力速度多快。在如今短跑运动员大约43公里(27英里)的时速下，像博尔特这种顶尖男选手大约会在0.085到0.09秒的时间内，向地面施加约等于5倍体重的力量。

Just for fun, I ask Weyand what kind of numbers a sprinter would need to complete the 100 meter dash in 9 seconds, on the nose. "To get to what would be required for nine flat, they would have to approach forces roughly six times their body weight, and a ground contact time of just over seven hundredths of a second," he says. At those figures, a sprinter could, in theory, reach a maximum speed of 13.5 meters per second—a hair over 30 miles per hour. But according to Weyand, no sprinter on Earth comes anywhere close to those numbers.

出于好奇，我问Weyand，如果想要在9秒内跑完100米，这些数字大约需要变成什么样。“如果想要在9秒内跑完百米，他们他大概需要在0.07秒左右的时间里向地面施加约6倍体重的力量。”他说。理论上，如果短跑选手能够跑出这个数据，最高时速会达到13米/秒——时速刚刚超过48.2公里(30英里)。但Weyand还说，地球上目前还没有能接近这个数字的人类。

That probably puts the theoretical limit for the 100 meter dash closer to 9.58 than 9.00. But Weyand, for his part, thinks athletes have plenty of room to improve. "If you put together a perfect human being, and the perfect race, I could certainly see something in the low 9.40-second range, maybe a little bit faster than that, under currently legal conditions," he says.

这意味着，相比9秒，百米纪录的极限可能还是更接近现在的纪录——9秒58。但Weyand也说，运动员们改进的空间还很大。“如果有一个完美的人类，跑了一场完美的比赛，在当前合理的状况下，我觉得能看到低于9秒40的成绩。”

Then again, who knows how those conditions could change. When Thomas Burke coiled into a crouch at the starting line for the first Olympic 100 meter dash, he did so without the speed-boosting benefits of modern nutrition, apparel, or training. He didn't even have starting blocks. Athletes at the Olympic Games in 2120 may well scoff at the rudimentary preparations of today’s sprinters too.

但话又说回来了，鬼才知道这个“合理的状况”最后会变成什么样。当Thomas Burke在首届奥运会的百米起跑线上蹲下的时候，他可是完全没有现代的营养条件、科技服装和合理训练的。他甚至连个起跑器都没有。等到2120年奥运会时，参赛的运动员们回头看今天的同行，可能也是一样的感觉。