To understand these differences, we need to explore the biomechanics of running, which can be divided into two major components: running kinematics, the way in which the body moves, and running kinetics, the relationship between movements and the forces that cause them. To understand the important kinetic differences between different kinds of foot strikes we will first consider key differences in running kinematics. Note that there is a continuum of different kinds of landings from landing on the heel (heel striking), landing simultaneously on the heel and ball of the foot (midfoot striking), and landing on the ball of the foot (forefoot striking). Again, for simplicity, we focus here on heel and forefoot striking, noting that midfoot striking is often intermediate.

The explanations below illustrate how and why a large collision is generated when heel striking and why such a small collision is generated when forefoot striking.

Here we focus on the difference between heel striking and forefoot striking (see bottom of page for more on midfoot striking which is often intermediate). In heel striking, the collision of the heel with the ground generates a significant impact transient, a nearly instantaneous, large force. This force sends a shock wave up through the body via the skeletal system. In forefoot striking, the collision of the forefoot with the ground generates a very minimal impact force with no impact transient.