Write a short paragraph that explains the central idea of the article Bolt is world's fastest runner. Use at least two details from the article to support your response.

Answer: Bolt running in between two other sprinters on a field ... The science explaining how Usain Bolt became the fastest human in the world ... This will be his last race; Bolt is set to retire after this running season (there's ... Fast-twitch muscle fibers are used to generate huge amounts of force, but they don't ...