When it comes to sustained foot and ankle strength for forefoot running, most of the growth in strength is going to come from the sensory input stimulating the bottom of the feet. This is why I really champion wearing barefoot-like shoes, like the Sockwa X8 or the Vibram KSO EVO because they give more sensory broadband than traditional running shoes. I think we are more convinced than ever that when the sensory nerves in the bottom of the feet participate more fully, the effects ripple across the lower leg, activating other motor nerve networks that not only directly stimulate greater muscle tone, but activate key withdrawal reflexes in the leg, helping mop-up mechanical inadequacies, giving you more top-notch mechanical efficiency during running. Read more here on my list of all the minimalist shoes and sandals most suitable for helping you improve and sustain an effective forefoot running style.