为什么有的人跑得那么快？

原标题：How do some people run so fast? The science of speed explained


Usain Bolt, the world's fastest person, ran a 100-meter sprint at a speed of 23.35 miles per hour (37.57 kilometers per hour).
世界上跑得最快的人是尤塞恩·博尔特，他百米短跑的速度为每小时23.35英里（37.57公里）。


That's mind-blowingly fast for a human. It's about the same speed as cruising in a car through your neighborhood or in a school zone. It might not seem that fast when you're in the car, but for a person? Few runners in the world can even come close.
对于人类而言，这个速度真是快得惊人。这大约相当于在社区或学校周边区域开车的速度。当你坐在车里时，可能不觉得车跑得有多快，但对于一个人来说就不同了。世界上很少有跑步者能接近这个速度。


There are several reasons why some people can run very fast while others tend to run more slowly. Genetics – the traits you inherit from your parents – play a role, but so do your choices and experiences.
有几个原因可以解释为什么有些人能跑得非常快，而其他人则跑得比较慢。来自父母的遗传基因是一个因素，但你的个人选择和经历也会产生影响。


One major factor that influences your ability to run fast is the structure of your body, including how your muscles work.
影响你快速奔跑能力的一个主要因素是你的身体结构，包括你的肌肉是如何工作的。


The human body has more than 600 muscles that work together, allowing you to move in different directions and at various speeds. These muscles are made up of groups of fibers. There are two main types: fast twitch and slow twitch.
人体有600多块肌肉协同工作，让你能够向不同的方向移动，并以不同的速度移动。这些肌肉由纤维群组成。纤维群主要有两种类型：快肌纤维和慢肌纤维。


Muscles have different mixes of these fiber types. For example, two muscles make up the calf: One is predominantly fast twitch – that's the gastrocnemius, used for sprinting and jumping. The other is mostly slow twitch – that's the soleus, used for walking and jogging.
肌肉由不同类型的纤维群混合组成。例如，小腿由两块肌肉组成：一块主要是快肌纤维——那是腓肠肌，用于短跑和跳跃。另一块主要是慢肌纤维——那是比目鱼肌，用于走路和慢跑。


Fast-twitch muscle fibers are larger and help your body move quickly and generate significant force. Sprinters tend to have an abundance of fast-twitch muscle fibers. However, this muscle fiber type also tires quickly, which limits how long you can run at top speed to relatively short distances.
快肌纤维较大，帮助你的身体快速移动并产生巨大的力量。短跑运动员往往有大量的快肌纤维。然而，这种肌肉纤维类型也很容易疲劳，这限制了你以最高速度跑步的时间，只能维持相对较短的距离。


Slow-twitch muscle fibers are smaller and help you run at slower speeds, but with greater endurance. Long-distance runners and competitive cyclists tend to have a lot of these muscles.
慢肌纤维较小，帮助你以较慢的速度但更强的耐力跑步。长跑运动员和竞技自行车手往往有很多这种肌肉。


How much you have of each type of muscle fiber – fast twitch and slow twitch – is mostly determined by your genes, so you'll have to work with what you're born with when it comes to muscle types. But exercises can help train those muscles.
你拥有的每种肌肉纤维——快肌纤维和慢肌纤维——的数量主要由你的基因决定，所以在肌肉类型方面，你将不得不使用你出生时所拥有的肌肉纤维。但是锻炼可以帮助训练