If your ankles hurt when running forefoot, certain parts of your forefoot strike landing pattern may be incorrect. For example, landing big-toe-first influences movement patterns of the ankle in ways that ratchet up ankle rolling, and the full consequence of this is an ankle sprain. To ensure stronger protections on the ankles during running, making initial ground-contact under the 5th toe was found to be a safer landing strategy of the foot. Read more here about the clear advantages and mechanical relevance of touching-down first under the 5th toe, not the big toe in forefoot 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.