Retail Focus Thursday: The Lateral Flare
We recall that The lateral flare is part of the outsole, where it is elongated laterally (as opposed to medially, as in a medially flared shoe), to create stability.
Look at the above example (left above). Notice how the cushioning is different at the lateral aspect of the outsole; in this case: two densities. In this case, Nike Cesium, there is no lateral flare but plenty of entry zone cushion ! In this case this is to “ease the foot into pronation” (keep the foot longer in supination) and is considered a motion control feature (along with dual density midsoles and torsional rigidity, among others).
The typical lateral flare however, as seen in the middle picture drawing, can be a good thing and acts differently than the soft lateral entry zone of the Cesium above. The typical lateral flare will help to pronate the rearfoot, helping minimize the risk for ankle inversion; something you do not want especially when trail running where heel strike is sometimes more pronounced. The Nike above on the other hand, without the lateral flare, will keep the foot in supination longer, and tends to increase stresses to the lateral column of the foot. Not a good trail running shoe example !
Typical lateral flares, speed up initial pronation (when walking we usually strike on the outside of the heel, as do some heel strike runners. The flare creates a greater distance to travel in the same amount of time; again; see center pic above). It does not appear to increase total pronation or affect impact forces. It is a good idea for one problem, but often creates another. Not everyone can handle an increased speed of pronation effectively: these folks need to suddenly decelerate the medially spinning leg. What will do that? Most likely the glutes (max and medius); the vastus medialis (contracting eccentrically) and the anterior leg muscles (like the tibialis anterior, extensor digitiorum longus, extensor hallucis longus). You have probably been reading our posts for some time now. How many individuals have competency in these muscles? Not many.
Regarding the lack of lateral flare in the Nike shoe above, this feature has a tendency to “close” the knee medially and “open “it laterally. On the other hand, a typical laterally flared shoe will open the medial knee joint line and close the lateral but this does depend on the degree of tibial torsion and varum. These lateral flare issues need to be strongly thought out when prescribing a shoe for a client. This can be a double edged sword. Arthritis is most likely going to effect the medial (inside) knee 1st so you will want to chose a shoe that does not compress that medial knee.
The bottom line? Proceed with caution with ANY shoe that has a motion control feature and know what you are recommending.
A little lost? Have no fear; the complete shoe fit program (with IFGEC certification if desired) is coming in the next few months. Watch here, on Facebook or Twitter for the announcement. What is the IFGEC you ask ? “The International Foot & Gait Education Council” , a group of experts brought together from around the world in a combined braintrust to further foot, gait, running form and shoe forward thinking.
The Gait Guys…Shoe Geeks Extroidinaire. Helping you help your clients make better shoe choices