The Great Myth of Rotating your Shoes : Here are the Actual Facts as we see them.
Everyone has heard the rules, rotate into new shoes about every 400-500 miles. We disagree, kind of, and we have talked about it on previous blog posts in the past and on our podcasts. Many shoe reps have agreed with the methods we employ for our runners.
The EVA foam often used in shoe manufacturing has a lifespan, or better put, a given number of compression and shear cycles. It can go through a rather fixed number of compression cycles before it loses its original structural properties, the older the foam gets the faster the degradation process and the more risks it poses for runners. It is known that EVA foam compressed into a focal vector or area over and over again becomes softer and more giving into that vector/area over time. Hence, if you have a compensation pattern or a known foot type (forefoot varus, forefoot valgus, rearfoot varus, rearfoot valgus or a combination of these 4) you will break down a certain region or zone of the shoe’s EVA foam. For example a forefoot varus foot type will often drive some heavy focal compression into the foam under the first metatarsal. However, if you combine it with a rear foot valgus it will drive shear forces and compression into the EVA foam along the entire medial aspect of the shoe (see the 2 pictures attached, you can see the evidence of excessive medial compression and medial shear in a foot that has severe rearfoot valgus and forefoot varus. This is a very poor shoe prescription for the foot type involved).
Here is what you need to do / know:
1- Know your athletes foot type so you can make more informed decisions.
2- Know the type of foam of the shoes you are recommending (ie. Altra uses A-Bound foam instead of EVA just as an example. A-Bound is an environmentally friendly energy-return compound is made of recycled materials. It reduces the impact of hard surfaces while still maintaining ground feedback. Traditional running shoe foam compresses 70-90% while A-Bound™ compresses 2-3x less so it won’t deform over time.). Cheap shoes use cheap materials. Altra goes the extra mile for foam quality and many others are beginning to follow suit. If you think you are getting a deal on shoes, know what “the deal” is, it just may be cheaper materials.
3- 500 miles is not the rule for everyone and every shoe. If you have a relatively neutral forefoot and you are a forefoot or midfoot strike runner you will get far more miles out of a shoe. If you depend on a stability shoe with dual densities of foam to slow your pronation and control your medial foot because of a rearfoot valgus and/or forefoot varus know that the shoe’s foam will break down less uniformly because of foam interface junctions and whatnot. This is a science. Engineers call it “the mechanics of material deformation”. We wonder how many mechanical engineers shoe companies have on board in their R&D divisions ? We know for a fact that a few do not. There was a reason we snuck quietly into the mechanical engineering departments of our Alma Mater and sat quietly in the “Materials” classes. At the time our roommates just told us it was cool class, little did we know why it was so interesting to us, until now.
4- Here is what we recommend. Fit the foot type to the right shoe selection. If you are weak in this territory consider taking our intense “National Shoe Fit” program. Fit is everything. Make the wrong choice for your client and the shoes will break down quicker and into poor and risky patterns. Make the right choice and be their hero. If you are looking for a way to improve clientele happiness and store loyalty our Shoe Fit Program is the way. Just read the testimonials here on our blog. Some of the top stores in the Nation have quietly taken the National Shoe Fit Program from us, they have good reason to. They also have good reason to keep it quiet, to get the edge on the competition.
You can email us to get this information and the e-file program download. Why not certify your entire store staff ?
Email us at firstname.lastname@example.org. This program will teach you foot anatomy, functional anatomy, shoe anatomy, foot types and matching foot type to shoe type as well as many other aspects of gait and lower limb biomechanics.
* 5- Try this recommendation. At 250 miles buy a new shoe to accompany your shoe that already has 250 miles. Now you are rotating 2 shoes. From this 250 mile point moving forward, alternate the newer show with the older shoe. This way you are never in a shoe that is notably more deformed in a specific area of the EVA foam because of your compensations, limitations or foot type. Essentially you are always just a day away from a newer shoe that has less driving force into abnormally compressed EVA foam. The older the shoe gets the more it accelerates your foot and body into that deformation and hence why many injuries occur as their shoes get older. Continue to alternate shoes on every other run (new, old, new, old). Once you hit 400-500 miles on the old shoes, ditch them and get a new pair again to restore the cycle once again. In fact, to be specific here is what we recommend. Monday, old shoe. Tuesday, new shoe. Wednesday do not run, rather, rest or cross train. Thursday go back to the older shoe. Friday new shoe and repeat. This way you are 4 days between runs in the older more deformed shoe. The one day off running in mid week gives tissues that were challenged by the “old shoe run” a bit more time to repair.
6- Dedicate your shoes to running only. Running gait is not the same as walking gait. Why would you want to break down the EVA foam at the rear foot during walking (because heel strike is normal in walking) when in running you are a mid-forefoot striker ? Keep walking shoes for walking, running shoes for running. Otherwise you are just asking for trouble.
Check out our National Shoe Fit program and certification process here as well as links to our other teaching DVD’s & e-downloads:
Shawn and Ivo. Helping you use your head (and shoe knowledge) better everyday.
The Gait Guys (have you checked out our RebelMouse page ? https://www.rebelmouse.com/TheGaitGuys/
Keeping up with our awesome informative podcasts ? It is all free stuff ! https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138
How about our youtube channel ? http://www.youtube.com/user/thegaitguys
How about our Facebook PAGE ? https://www.facebook.com/pages/The-Gait-Guys/169366033103080