Elite sprinters attack ground to maximise speed

Scientists have unlocked the secret behind Usain Bolt's extraordinary speed - he delivers a firm, rapid punch to the ground!
The world's fastest sprinters have unique gait features that account for their ability to achieve fast speeds, scientists have found.
Researchers from Southern Methodist University, Dallas suggest that the secret to elite sprinting speeds lies in the distinct limb dynamics sprinters use to elevate ground forces upon foot-ground impact.
"Our new studies show that these elite sprinters don't use their legs to just bounce off the ground as most other runners do," said Ken Clark, lead author of the research from the SMU Locomotor Performance Laboratory.

"The top sprinters have developed a wind-up and delivery mechanism to augment impact forces. Other runners do not do so," Clark said.
Previous studies had established that faster runners attain faster speeds by hitting the ground more forcefully than other runners do in relation to their body weight. However, how faster runners are able to do this was unknown.

"Elite speed athletes have a running pattern that is distinct," Clark said.
"Our data indicate the fastest sprinters each have identified the same solution for maximising speed, which strongly implies that when you put the physics and the biology together, there's only one way to sprint really fast," he said.

The critical and distinctive gait features identified by the research occur as the lower limb approaches and impacts the ground, said study co-author and running mechanics expert Peter Weyand, director of the SMU Locomotor Performance Lab.
"We found that the fastest athletes all do the same thing to apply the greater forces needed to attain faster speeds," Weyand said.
"They cock the knee high before driving the foot into the ground, while maintaining a stiff ankle. These actions elevate ground forces by stopping the lower leg abruptly upon impact," Weyand said.
The fastest runners decelerate their foot and ankle in just over two-hundredths of a second after initial contact with the ground, researchers said.

The tests conducted compared competitive sprinters to other fast-running athletes.
The competitive sprinting group included track athletes who specialised in the 100- and 200-metre events. More than half had international experience and had participated in the Olympics and Track and Field World Championships.
They were compared to a group of athletes that included competitive soccer, lacrosse and football players.
The findings were published in the Journal of Applied Physiology and The Journal of Experimental Biology.