Running Barefoot: Biomechanics of Foot Strike | Mindfulness & Mindful Running | Scoop.it
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.

Therefore, quite simply, a runner can avoid experiencing the large impact force by forefoot striking properly.