I’ve always advocated forefoot striking as opposed to rearfoot striking. The benefits have a growing scientific body of evidence to lean on. Whether you’re looking to prevent injuries, improve your performance, or increase your efficiency, forefoot striking can help you achieve your goals.
However, I’ve never explained exactly what makes forefoot striking better. For those of you who haven’t just accepted my statements at face value, this post is for you.
There are scientific differences between the forefoot strike and the rearfoot strike. I’m not referring to the obvious “your heel touches first the ground” or “the ball of your foot touches the ground first”. I’m referring to the physics of the foot strike, specifically Newton’s Second Law of Motion (Force = Mass * Acceleration).
In a rearfoot strike, your heel touches the ground first. This generates an instantaneous impact force which absorbs into your body [I’m going to refer to this as Force A]. Then, as your foot rolls forward, you generate an impact force a second time, this time over a longer time period (a few tenths of a second, depending on your speed) [I’m going to refer to this as Force B]. In the interest of fairness, research has shown that traditional running shoes with built up heel cushions can absorb up to about 10% of that first instantaneous impact force.
In a forefoot strike, the ball of your foot touches first. You create an impact force almost identical to Force B generated during a rearfoot strike. This is spread out over the same, slower time period (tenths of a second) as in the rearfoot strike.
In plain English, this means that the impact Force A is almost completely eliminated by forefoot striking, while impact Force B is nearly identical for both foot strikes. Over thousands of steps per mile, you can begin to see how forefoot striking reduces stress on your feet and legs.
In Part II of this article, we’ll dig into detail on why Force A is so damaging to your feet, legs, and joints. You’ll discover that not only are you eliminating one of two forces – but that the force you eliminate is much more dangerous to your physical health. Finally, I’ll break all of this down into an easy-to-understand chart that explains the differences between the two forces and the two foot strikes.