Q: does they? i saw that usain bolt (the fastest man on earth) doesn't have much muscle on his leg. I know that his tall but i am short so if i build leg muscle can i run faster than now?
A: Bolt does have muscles on his legs. It might not seem so since he is very tall, but speed is strength. All sprinters have strong muscles on their legs. Middle distance and distance runners have strong muscles but they can not be as large as sprinters because they have to carry those muscles with them as they run. All elite runners do weights, and plyometric exercises to build strength.