Here is something to think about. As one midfoot strikes the foot during walking or running the individuals body mass is typically directly over the foot. When this occurs in a zero drop shoe (ie. flat, your rear and forefoot are on the same plane) the tibia-ankle is at the very least, at 90 degrees. Meaning, the tibia is at the very least at 90 degrees and is at the very least perpendicular to the ground and plane that the foot is on. And with just a little bit of forward body mass movement over the foot the critical and necessary range of 110-115 plus degrees of ankle dorsiflexion (depending on your reference source) is achieved. This means that one does not have to prostitute the foot into greater than normal pronation to drop the arch further to gain the extra amount of ankle rocker (dorsiflexion) that is necessary to pass over the foot.
However, think about this. What if that same foot is in a stacked heel shoe. There are plenty of shoes still out there that have a ramp delta that is above zero drop. So, what we have is a shoe that has the heel higher than the forefoot, a sloped shoe. IF this same foot midfoot strikes what happens now ?Well, midfoot strike now occurs in a relatively greater plantarflexed posture (ie. heel is raised higher than the forefoot because of the shoe). This means we are not anywhere near the 115 degrees necessary for normal gait, timely heel departure, timely forefoot load, timely hip extension, timely gluteal activation etc. These timely gait events are paramount to normal gait and when they are altered injury and altered tissue loads can occur. Altered motor recruitment patterns are likely to ensue. In the scenario proposed, as the body mass moves over the slightly plantarflexed foot we might now only get to 90 degrees of ankle rocker before the body mass is far enough forward to create the passive heel rise during late-midstance phase of gait. And when the body can only get 90 degrees of ankle dorsiflexion/rocker during midstance the extra amount of dorsiflexion range may need to come from some other joint. It may come from more than normal midfoot pronation, knee hyperextension, knee valgus etc. This is potentially a long list of compensations.
Food for thought, especially for those who say to others. “Hey dude, chuck your ramped shoes and go minimialism or barefoot. Just go for it. I did and I was fine !”
The Gait Guys