In the early 1960s, Dick Fosbury tried his hand at almost every sport, but never excelled at anything, until, at the age of 16, he turned to the high jump. But when he couldn't compete against the strong athletes at his college using the standard high jump techniques of the time, Fosbury tried to jump a different way: backwards. Instead of jumping with his face towards the bar, bringing each leg over in the traditional straddle method, he jumped with his back towards the bar. Fosbury improved his record by over half a foot, and left his coaches amazed by this strange new style of high jumping. During the next few years, Fosbury perfected his high jump style, won the U.S. National trials, and assured his place in the 1968 Olympics in Mexico. In the Olympic Games, Fosbury amazed the world with his new technique, winning a gold metal with an Olympic record leap of 2.24 meters. By the next Olympic Games, almost all of the competing of high jumpers had adopted what came to be known as the Fosbury Flop. What's the secret behind the technique? It lies in a physics concept called the center of mass. For every object, we can locate the average position of all of its mass by taking into account how the mass is spread around the object. For instance, the center of mass of a flat, rectangular object of uniform density will be in the intersection of both diagonals, in equal distance from each corner. We can find the center of mass for other objects by similar calculations, or by finding the object's balancing point, which lies right underneath its center of mass. Try balancing a broom by holding it and slowly bringing your hands together until they meet. This balancing point lies right underneath the broom's center of mass. We humans also have a center of mass. When most people stand up, their center of mass is around the belly, but what happens to your center of mass when you lift your hands in the air? Your center of mass moves upwards. It moves all the time as you move through the day, based on how your body is positioned. It can even move outside of your body. When you bend forward, your center of mass is located below your bent belly in a place where there is no mass at all. Weird to think about, but that's the average position of all your mass. Many objects' center of mass are outside their bodies. Think of doughnuts or boomerangs. Now look at the Fosbury Flop, and follow the position of the center of mass of the jumper. The jumper runs very fast, so he can divert his horizontal velocity to vertical velocity, and jumps. Wait for it...there. Look at the jumper's center of mass as his body bends backward. It's below the bar. That is the secret behind the jump. With the old, pre-Fosbury techniques, the jumper had to apply enough force to lift his center of mass above the bar by a few inches in order to clear it. The Fosbury Flopper doesn't have to do that. The genius of the Fosbury Flop is that the jumper can apply the same amount of force, but raise his body much higher than before. That means he can raise the bar so high that even when his center of mass can't go any higher, his arching body can. Fosbury's technique brought the high jump to new heights by splitting the jumper's body away from his center of mass, giving it that much more room to clear higher and higher bars. So the Fosbury Flop may be sports history's only great leap forward, that is also a great leap backward.
1960 年代初 Dick Fosbury 遍尝各种体育项目, 却始终没在哪一项出头 直到 16 岁那年,他试了跳高运动 开始,当他无法击败 学院中的优异选手 使用当时的标准式跳法, Fosbury 尝试与众不同的方法:背跃 不像一般选手般面向杆子翻转 (两脚依次翻过 的剪刀式(straddle)跳法) 而Fosbury 背向横杆越过 如此,他的成绩跃进了 15.24 公分, 教练也折服 在这诡异的新跳法面前。 往后数年, Fosbury 完成了他的背跃绝技, 通过了美国的国手选拔, 并在 1968 年墨西哥城奥运会 挣得了历史定位 在奥运会上,Fosbury 惊艳了全世界 并以他的独门绝活一举夺下金牌, 还顺便推进了奥委会记录,由 2.22 到 2.24 公尺。 于是下一届奥运会中 几乎所有选手都使用了 新的背跃式跳法 Fosbury 的鱼跃 (一名记者,认为以弯曲的背部坠落软垫, 像上岸的鱼乱跳 ) 这个招式背后的秘密是什么? 答案藏在一个物理概念里: 称为质量中心(质心)。 对任何物体 我们都可以藉由 考虑物体质量 在三维空间中的分布情形 来确定其质量的平均位置。 例如,一个扁平、长方形、 密度均一的物体,其质心 会落在两对角线的交点, 与其它角落等距。 对于别的物体 我们可以透过类似的方法 来寻找其质量中心。 或是直接找物体的平衡点, 平衡点会落在质心的正下方。 试试用双手托着扫把的柄, 并轻轻用力让两手往内滑动,直到手掌合十。 这时平衡点就在扫把的质心下 这时平衡点就在扫把的质心下 人体自然也有一个质心。 大多数人站直时, 质心位在肚脐附近。 当你举起双手, 你的质心会有啥变化? 质心会向上移动 在你一天的活动中,你的质心据你的姿势 四处动来动去。 甚至有些姿势,会让 你的质心位在身体的外部。 例如腰向前仰 质心会在你的腹部下方, 即使那一点空无一物。 想起来似乎怪怪的,但它确实是这时 你身体所有部分的平均位置。 还有许多物品的质心 处在物品外面, 例子有甜甜圈,和回飞镖。 现在我们能回来看 Fosbury 的后跃了, 注意动作中运动员的质心位置。 选手首先高速助跑, 将一部分的水平速度 转移成垂直起跳的速度,于是跳! 留神......就这儿。 注意到选手身体往后弓起时 质心所在位置吗? 事实上它还在横杆之下! 这就是背跃绝技的奥秘。 在 Fosbury 登场以前,跳高的技术 全仰赖选手拼命使劲 为了将他们的质心抬到杆子以上数吋 才能避免越过时把杆子撞掉。 但背跃式跳法回避了这个瓶颈。 Fosbury 方法的天才之处在于, 选手花同样力气,其质心和原本一样高, 身体却能处在更高位。 这代表杆子能继续往上摆, 即使质心的高度再也提升不了 弯曲的身体却可以由上方跳过去。 Fosbury 的新招式让跳高的 世界纪录连创新高, 原理是尽量弯曲身体, 使选手的质心离身体越远越好, 因此有更多空间能运用于 闪过不断加高的横杆。 因此可以说,Fosbury 绝技是运动史上 的一次向前大飞跃, 并且是向后飞跃。