Footwear For Runners with Flat Feet
In this study, motion control shoes were compared to neutral shoes in recreational runners with flat feet. The medical term for flat feet is pronation. Women who ran short distances (1.5 km or about one mile) several times a week were tested. They all had signs of over pronating.

Muscles along the inside of the ankle and foot called invertors are supposed to control foot pronation. Less active invertors place the foot at increased risk for injury.

Without proper control of the foot, pronation occurs. An increase load is transferred to the medial (arch side of the) foot and under the first metatarsal (big toe) area. Then the foot can't handle the impact during running.

Using motion control shoes prevents excessive pronation. This means fewer pronation-related injuries. The shoes have a special design using different materials to absorb the impact of landing.

Testing showed the plantar force load using the special shoes was the same at the beginning and at the end of the 1.5 run. Without the adapted shoes, the load increased at the end of the relatively short run.

It's not known whether the motion control shoe design has the same beneficial effect over longer distances. More studies are needed to find out the effect with more miles. It does appear that injuries related to excessive pronation may be prevented for recreational runners over short distances.
References
Roy T. H. Cheung, BSc(Hons)PT, and Gabriel Y. F. Ng, PhD, MPhty, PDPT. Influence of Different Footwear on Force of Landing During Running. In Physical Therapy. May 2008. Vol. 88. No. 5. Pp. 620-628.