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It's not fair!
真不公平！
What's not fair?
什么不公平？
I was rereading the Constitution of the United States. It sayshere that “All people are created equal.”
我又读了一遍《美国宪法》，上面写着：“人人生而平等。”
That's just not true!
事实并非如此!
What do you mean?
你想说什么？
Well, it's always being my dream to become the Olympic champion in the 100-meter-dash.
成为奥运会的百米短跑冠军一直是我的梦想。
But no matter how hard I train, I'm just not fast enough.
可是，无论我多么努力，我就是跑不了那么快。
You just realize this now.
你才意识到啊！
Some guys are simply faster than everyone else.
有些人就是比别人都跑得快。
That's because some people are born with more faster twitch muscle fiber than others.
那是因为他们天生比他人多快收缩肌纤维。
With what?
有更多什么？
That's a big part of what make people faster than others.
快收缩肌纤维大大地决定了跑步速度。
Muscles are made of two kinds offibers–fast twitch and slow twitch.
肌肉有两种纤维构成：快收缩肌肉纤维和慢收缩肌肉纤维。
What's the difference?
有什么不同吗？
Slow-twitch fibers use energy aerobically and can work for long periods of time before gettingtired.
慢收缩肌肉纤维用于有氧耗能，适合耐力性运动。
So they can contract more slowly, but can keep going without burning themselves out.
所以慢收缩肌肉纤维收缩更慢，但是持续时间更长。
Exactly, since they have to keep going for long periods.
说的对，因为马拉松耗能耗时长。
So sprinters have a lot of fast twitch muscle fiber.
那么，马拉松选手肯定有很多慢收缩肌肉纤维了。
Right! Fast twitch fibers consume energy quickly and are good for short, powerful bursts ofmovement like sprinting and jumping.
没错！慢收缩肌肉纤维富含肌红蛋白。肌红蛋白可帮助肌细胞将氧转运到线粒体，而线粒体是细胞能源工厂。
World-class sprinters typically have about 80% fast twitchmuscle fiber.
对，快收缩肌肉纤维耗能快，特别适合短而有力的爆发性动作，比如短跑和跳跃，世界级短跑健将体内80%肌肉都是快收缩肌肉纤维。
Luck dogs!
真是幸福！
And, of course, they train incredibly hard to develop their natural gifts. Olympic gold is not wonby muscle fiber alone.
当然，他们不仅仅靠天赋，还有艰苦地训练来完善技能。获得奥运金牌可并非肌肉纤维就可以。
But it certainly helps!
但是不得不承认肌肉纤维起了作用。
