It's all about the force. After studying the physics behind some of the world’s fastest runners, researchers came up with a new model they say could make anyone faster. It may help injured runners recover faster, too.

One equation to predict speed: a simple two-mass model ― based on the force resulting from the impact of the lower leg (shin, ankle and foot) on the ground, and the force that lifts and supports the rest of the body.

Two forces: The total force of the shin, ankle and foot striking the ground, and the total force of the rest of the body striking the ground.

Three things in order to predict a runner’s speed: • How much time a runner’s foot spends on the ground • How much time the runner is in the air • How quickly the ankle is moving when the runner hits the ground