The Uses of Medial Posting in Running Shoes

There are literally hundreds of different running shoe brands and models, and they are all probably designed to meet the needs of each different runner. Each brand will use their own set of characteristics and each model made by each brand has a different set of design features that they use. The problem with the prescribing and buying of running shoes is that each runner will have a different foot shape and size as well as a different way that the foot functions and the way that they run and all of this needs to be matched up to the correct characteristics of a running shoe to meet their needs. These different characteristics include features such as the drop, which is the difference between the height of the shoe under the ball of the foot versus the heel. The amount of cushioning in different parts of the running shoe will also vary in different shoes and is yet another variable design feature. Some runners need more cushioning, and some runners need less. The midsole which is the bottom part of the shoe is one of the features of the running shoe that varies the most. The midsole can be a single density or dual density.

A dual density feature is what is known as a medial post. This is when there is a higher density material within the midsole on the medial side of the midsole only. The medial posting was first introduced in 1984 in the Tiger X-Caliber GT running shoe which later became the ASICS Gel Kayano. The original purpose of this medial post feature was as one of a number of motion control design features in running shoes to control ‘overpronation‘ of the foot in the runner. At that time ‘overpronation’ was considered a problem for runners. This is when the foot rolled inwards excessively at the ankle joint, so it does make some sense that the shoe be firmer in that medial area of the midsole to try and stop it. However, the evidence of the medial posting being to able to do that is not very good. The reason for this is that the medial posting will have differing effects on different runners and just how wells that is works will depend on what is causing the ‘overpronation’. This is also based on the assumption that something needs to be done about the ‘overpronation’, which is not always the case. In some runners, the medial posting is particularly useful because it can move the centre of ground reaction forces medially. This will alter lever arms around the joints in the foot and some clinicians find that particularly useful in the management of some runners’ problems.

Medial posting as a design feature that is used in running shoes is being used less now and a number of brands have dropped it. That is a shame as it still does have practical uses in some runners who will benefit from it. It is not going to be of much use to those runners who do not need it.

Craig Payne is a University lecturer, runner, cynic, researcher, skeptic, forum admin, woo basher, clinician, rabble-rouser, blogger and a dad.