The very first part of your foot that should land on the ground when running is your forefoot as it has major implications for injury prevention. For instance, research has found that high bending strain and damaging pressures on the foot can be easily avoided in running by making initial ground-contact towards the outer-side of the forefoot, just under the 4th and 5th toes. Read more here about the full advantage and mechanical relevance of touching-down first under the 5th toe, not under the big-toe, nor on the heel (heel strike) in running.
BSc Neurobiology; MSc Biomechanics candidate, ultra minimalist runner & founder of RunForefoot. I was a heel striker, always injured. I was inspired by the great Tirunesh Dibaba to try forefoot running. Now, I'm injury free. This is why I launched Run Forefoot, to advocate the health & performance benefits of forefoot running and to raise awareness on the dangers of heel striking, because the world needs to know.