The short foot exercise is an exercise that is widely recommended for the treatment of flat foot or overpronation.
The exercise is carried out by shortening the distance between the heel and the base of the hallux contracting the muscles in the arch to slide the forefoot posteriorly along the ground.
There is some controversy about the SFA as it is assumed that it will only help those flat feet that are due to a weakness of the muscles and not on other causes of flat feet or overpronation. This makes sense, if a weakness in the muscle is the cause of the problem then a strengthening of them should be the solution. If there are other causes then strengthening is probably not going to help unless the actual cause is addressed.