Usain Bolt is an example of this. I remember being totally shocked when he ran the 100m in 9.59 [1]. Check out this awesome graph from the "Men's 100 m progression" wikipedia page.

[1]https://www.youtube.com/watch?v=3nbjhpcZ9_g [2]http://upload.wikimedia.org/wikipedia/commons/6/62/World_rec...