人到底能跑多快？

12!10.6!9.95!9.58!一個個抽象的數(shù)字，見證了人類在百米跑道上挑戰(zhàn)自我的一個個勝利瞬間。提高的雖然只有短短零點零幾秒的成績，我們卻已追逐上百年。下一位書寫傳奇的英雄是誰，哪里又是人類速度的真正極限?

Usain Bolt set new world records for the 100 and 200 metres at the World Championships in Berlin a few months ago. His achievements have raised the question: how fast can a man run?

In 1968， an American Jim Hines became the first man to break the 10 second barrier in the 100 metre sprint1).The record was chipped away2) at steadily until Usain Bolt burst upon3) the scene.

Since then the record has tumbled4) race after race: from 9.72 in May 2008 to 9.69 three months later to 9.58 in August 2009. The sprinter himself thinks he can run the race at 9.4 seconds.

Analysts agree that he can improve his performance. He still slows down at the end of the race when he knows that he has won by a clear distance， his overall technique could still be refined and crucially5) he has not run the race with the legally allowed fair wind6) behind him.

But what is the ultimate best time for the 100 metres?

At 6ft 5ins (1.96m) Bolt is much taller than other Olympic sprinters who are normally between 5ft 9ins (1.75m) and 6ft 3ins (1.9m).

For athletes any taller it had been thought that any additional benefit from a longer stride7) would be outweighed8) by their greater bulk.

Some scientists have speculated that Bolt might have more so-called \"fast twitch9)\" muscles fibres for a man of his height. These provide sprinters with the bursts of power they need for fast acceleration.

But others have suggested that taller men simply have not been attracted to athletics， preferring to devote themselves to more lucrative10) sports such as basketball or American football. According to Raphael Brandon， of the English Institute of Sport， more tall powerful athletes might now be inspired by Bolt's example and be drawn to sprint events. That may well bring the time down yet further.

To do it the human body will have to be able to cope with more forces placed upon it. But the key limiting factor， he says， is that sprinters have to have their feet on the ground for a proportion11) of the time to generate their pace.

\"I think there will come a point where to run any faster you will have to spend so little time on the ground that you won't actually be able to generate the speed.\" Mr. Brandon believes that it is highly unlikely that anyone will be able to run faster than 9.2 seconds. But he is the first to admit that for generations people have been suggesting limits for athletic events which have been subsequently been smashed12).

在幾個月前的柏林世錦賽上，尤塞恩·博爾特刷新了100米和200米兩項世界紀錄。他的成績讓人們不禁要問:人到底能跑多快?

1968年，美國人吉姆·海因斯在100米短跑比賽中成為突破10秒大關的第一人。這一紀錄不斷被改寫，但提升空間都很小，直至尤塞恩·博爾特橫空出世。

自此，這一紀錄在一場又一場的比賽中變得不堪一擊:2008年5月是9.72秒，三個月后是9.69秒，到2009年8月又成了9.58秒。這位短跑運動員自認為可以用9.4秒跑完比賽。

分析人士也一致認為，博爾特還能跑出更好的成績。當臨近比賽終點，他意識到自己已經(jīng)遙遙領先時，還放慢了腳步。他各方面的技術仍有精進的空間，尤為重要的是，他在比賽時，身后并沒有規(guī)則允許范圍內(nèi)的順風。

但是，100米短跑的最好成績最后到底會是多少呢?

身高6英尺5英寸(1.96米)的博爾特要比其他奧運會短跑選手高出許多，這些人的身高一般都在5英尺9英寸(1.75米)到6英尺3英寸(1.9米)之間。

人們一直以為，身材高大的田徑運動員，雖然步幅較大，但這種優(yōu)勢會因其體重較重而化為烏有。

一些科學家推測，博爾特可能比與他同樣身高的其他人多一些所謂的“快速抽動”肌纖維，這些肌纖維能夠為短跑運動員帶來迅捷加速時所需要的爆發(fā)力。

但是，已有另外的科學家提出說，身材高大的人是不會對田徑運動感興趣的，他們都偏愛投身于更為有利可圖的運動，比如籃球或美式足球。據(jù)英國體育研究所的拉斐爾·布蘭登稱，或許是受到博爾特示范效應的激勵，現(xiàn)在越來越多高大健壯的運動員開始走向短跑賽場。這樣一來，跑完100米的時間很有可能還會進一步縮短。

要做到這一點，人體就必須克服施加在身體上更多的阻力。不過他表示，關鍵的制約因素在于，短跑運動員在跑步過程中，速度產(chǎn)生的前提是雙腳必須與地面接觸，而這會消耗一部分時間。

“我想，將來要想跑得更快，就必須用極少的時間去觸地，當這一時間少到實際上已經(jīng)導致無法產(chǎn)生速度時，就達到極限了?！辈继m登相信，任何人跑出9.2秒的可能性都微乎其微。不過，他也第一個承認，幾代人以來，人們總在不斷地提出田徑比賽的極限，可是隨后極限又紛紛被打破。

Vocabulary

1.sprint [sprInt] n. 短距離的全速奔跑

2.chip away: 逐步瓦解，削弱

3.burst upon: 突然來到

4.tumble [5tQmbl] vi. 被推翻，遭傾覆

5.crucially [5kru:FElI] adv. 關鍵性地，至關重要地

6.fair wind: 順風;fair [fZE] adj. (風、潮水)(向)順的

7.stride [straId] n. 步幅

8.outweigh [aut5weI] vt. 在價值(或重要性、影響等)方面超過

9.twitch [twItF] n. 抽動，抽搐

10.lucrative [lju:krEtIv] adj. 生利的，賺錢的

11.proportion [prEu5pC:FEn] n. 部分

12.smash [smAF] vt. (嘩啦一聲)打碎，打破