Usain Bolt and the limits of human speed
Scientific advancement is pushing performance to the point where future limits are likely to lie largely where we decide to set them.
How fast might human beings ultimately run?
Usain Bolt's recent assault on the track and field record book – running 9.58 in the 100m and reaching a top speed of nearly 28 mph – has raised this question at a crucial crossroads for organized athletics. While specific predictions by modern science are not precise, the general influence of scientific advancement is poised to overwhelm human performance and organized athletics as we have known them.
Although we can readily quantify the forces acting on the body and predict the motion they produce using classical Newtonian mechanics, we still have an incomplete understanding of the process of force production within the body, and how the body's internal forces eventually translate into motion.
Conceivably, the secret to blazing running speeds might be explained by either of two abilities: repositioning the limbs quickly through the air, or hitting the ground forcefully with each step. Contrary to intuition, fast runners achieve their greater speeds, not by repositioning their legs any more rapidly, but rather by hitting the ground with greater force and quickness than slower runners do.
How hard and how quickly do elite sprinters hit the ground? Once up to speed, an athlete like Usain Bolt will hit the ground with a force equivalent to roughly 1,000 pounds, and do so within five 100ths of a second of the first instant of foot-ground contact.