How fast can a human run?

Question

I'm a runner (cross country) and I'm always amazed at how fast Olympic sprinters are. There's a lot of hype about those in the 100-meter dash being the fastest in the world, and we're constantly seeing the 100-meter time dropping. But is there a limit? How fast can human being, propelled only by its own energy (i.e. without any external assistance) run?

Answer 1

Studies done by Peter Weyand, Professor of Applied Physiology and Biomechanics from Southern Methodist University, suggest yes but only to about 35-40 mph. Usain Bolt holds the record for the fastest 100 meter at around 28 mph. The reason for this limit is due to the limits of the fast-twitch fibers of muscles.