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Find Your Shoe Replacement Sweet Spot: A MilestonePod DIY Guide

Do you wear your shoes well past their prime? You could be risking injury.

Do you replace your shoes too soon? You could be wasting money.

If you are a fan of the MilestonePod you may have seen a recent article about Yosh, a Pod fan from Massachusetts.  Yosh spent the past year replacing his shoes every 300 miles like clockwork. He also happened to enjoy his first year of injury free running. This begged the question: was he was wasting money by buying new shoes every 300 miles or was it indeed the reason he stayed healthy? The Milestone Sports team checked into his data and sure enough, he was changing his shoes at exactly the right moment – when his rate of impact (ROI) started to increase.

The lower your rate of impact, the better you and your shoe disperses the force of landing.  After many miles of training, the foam in your shoe starts to break down, causing your body to take more shock upon landing. As a result, your rate of impact will increase.

What did we look at to help Yosh? Rate of Impact + Shoe Odometer. This is the graph that Yosh used to determine when his shoes were wearing out and they needed to replaced:

rate-of-impact-increasing-with-shoe-wear

With the new “Run Log Export” feature of the MilestonePod App, anyone can plot their shoe mileage and rate of impact to see exactly when to replace their running shoes. Here’s how:

a). Export your run log (Menu > Settings > Export Run Log to Excel)

b). Sort by “Model” then keep only the shoe you want to plot. Delete all other rows

c). Then, sort by “Accumulated Distance” (smallest to largest)

d). In the empty column after “ROI High %” (column Z) input this equation:   =0*W2+X2*0.5+Y2

e). Copy this equation down the entire column

f). Name the column (i.e. ROI summary)

g). Select only “Accumulated Distance” + the new ROI columns (use “Command” or “Control” key)

h). Click Insert > Chart > Scatterplot

i). Right click on any data point and select “Add chart element” > Trendline

 

Pay attention to the general trend of when the points increase.  For Yosh, the trendline continued up the entire time, but he did not have consistently high rates of impact until around 300 miles. Some runners will have a higher ROI starting point even with new shoes (based on personal running form), making it even more important to look at trend increase vs. the bottom line number.

In this next example from a Pittsburgh Marathon runner, you can see the rate of impact consistently increases around 350 miles.  The scattered high points before 350 miles and the low points after 350 miles could be attributed to non-shoe factors such as fatigue or softer than normal running surface.

 

shoe-wear-2-1

There are many factors that affect shoe life and rate of impact, such as running form, shoe type and running surface. Adhering only to the industry standard of “300-500 miles” may put you in harm’s way. Instead, let the Pod auto-track your Shoe Odometer and rate of impact, and you will always know exactly when you need new shoes.

Author notes:

For the best data, we recommend waiting until you have at least 250 miles on your shoes prior to plotting your graph.

Some data may not be available for all runs due to release dates.  Remember Milestone Sports does big things, but is still a young company.

Author: Steve Suydam

Steve is a PhD and Director of Research at Milestone Sports. He can be reached at steve@milestonepod.com.