In part III of our plantar fasciitis series by @jfitboyd, we demonstrate a highly effective FUNCTIONAL exercise for developing eccentric posterior tibialis strength. Traditional strengthening with a theraband, into plantar flexion and inversion, is still a great exercise. But once adequate motor control/strength has developed, incorporation of functional strengthening is recommended.
As stated in previous posts, one cause of plantar fasciitis is prolonged pronation. This is often due to posterior tibialis—known commonly as the post tib—weakness. The post tib is a primary arch stabilizer as it ECCENTRICALLY controls pronation. Therefore, developing strength of the post tib is critical in helping reduce over-lengthening of the fascia, which can result in microtears and periosteal lifting (bone spurs). A traditional way to strengthen the post tib is with a Theraband around the foot while sitting in a chair or lying down.
However, a more functional approach is to perform a lateral step down. This will not only train the post tib, but also intrinsic musculature of the foot as well as the glute medius muscle as an added bonus. When you descend into the squat, your foot will naturally pronate. This pronation must be eccentrically controlled by your post tib.
HOW TO: Start with both feet on top of a step. Next, slowly lower the unaffected leg down off the side of the step to lightly touch the heel to the floor. Then return to the original position with both feet on the step. If you do not have a step, a box works just as well for this exercise.
Remember! Maintain proper knee alignment: Knee in line with the 2nd toe and not passing in front of the toes.