One of the many reasons heel striking is bad for running is that the high impact that travels heel to toe was found to cause excessive motions of the foot which increases strain on the foot-ankle complex.
More specifically, heel striking when running is typically accompanied by a burst of high impact on the heel. This heavy impact then travels narrowly through the middle of the foot and becomes heavily localized in the middle of the forefoot. This will negatively affect the stability of the foot because the foot is forced to pronate more to try and minimize the excessive impact pressure (because the impact cannot dissipate over a larger area of the foot, like it does in forefoot running). This is how heel strike running creates foot mechanics that work against you. Read more Read more here!
