Usain Bolt: the fastest man alive is 6'5" and 207 pounds. Being this large is rare for a sprinter because 207 pounds takes a lot of work to accelerate. To make up for this disadvantage he sprints quite differently than others.
His average stride is 2.44 meters long. This means that in a 100 meter race he only takes 41 strides. That saves a lot of time because the more times that you come in contact with the ground, the more time it takes to complete the race. In the World Championship in Berlin, Bolt's closest competitor made 2.22 meter strides, resulting in about 45 steps through the 100 m race. Bolt finished in 9.58 seconds(the world record), with an average speed of 10.44 m/s and maximum speed of 12.42 m/s.
Long strides is not the only thing Usain Bolt does differently to improve his speed. Every time bolts feet touch the ground he rotates his body about 20 degrees from the vertical forward as he pushes off from the ground. Being so tall he has a lot of gravitational torque when he leans forward. He uses this torque to his advantage by allowing his body to free fall forward.
Take a look at Bolt's record breaking race in the world championship in Berlin.