When Are Your Running Shoes Dead?

Running shoes wear out more quickly than you might think.  There are many rules flying around out there about when shoes need to be replaced.  Shoe companies, retailers, and clinicians say after “300-500 miles”. Or after “3-6 months or regular running”.  Or “when you start to feel foot or lower leg pain”.  Runners themselves often say “when there’s no more tread on the bottom”.  Or “when I have holes in the upper”.  Or “when they smell too bad to tolerate anymore”.


While there’s still rubber, it’s wearing smooth and thin. This shoe is past it’s useful life outside of maybe mowing the lawn

Here’s a conversation I have many times each month in my clinic as I interview a new client who suffers from some injury somewhere between the low back and the feet:
Me: “Are those the shoes you’re currently running in?”
Client: “Yes I love these shoes and they’ve been discontinued”
Me: “May I take a look?”
Client: “Yes they still have some tread left on the bottom and sorry they’re so smelly”
Me: “How long have you been running in this pair?”
Client: “Maybe 2 years”
Me: “ Do you wear them just for running or do you wear them day to day too?”
Client: “ Oh I wear them to the gym and to hike too”

You get the picture.  The common rule for consumers is that if there is still rubber left on the bottom, and the uppers are still mostly intact with a mere hole or two, that the shoe is still ok.  Unfortunately, it’s the mid sole foam that wears out first.  The soft white or grey stuff between our foot and the rubber breaks down well before the rest of the shoe shows much wear.  It can develop horizontal lines, it can shred and get super dirty.  But mostly it shows little visible wear.


Notice the stress lines and wear in the grey mid sole foam

Pain in the feet or legs is probably the best indicator that the shoes are done for.  But waiting for pain to tell you when your shoes are worn isn’t ideal as it can lead to frustration and expense that far outstrips the cost of a $100 pair of shoes.  Now there’s a way to tell when the foam has lost it’s life.

A former CU Cross Country running star, Connor Winter, along with CU professor Roger Kramm  are developing a small, light weight device called “Shoe Sense”.  The sensor will tell you when the foam in the mid sole is shot and no longer supports running.  The idea was spawned when Connor realized how important fresh shoes (like a new pair each month to support his 100+ mile/week training volume) were to his performance and his longevity and health as an elite runner.

Connor and Dr Kramm are working to create a database that catalogues every shoe and it’s wear pattern as well as it’s overall life relative to your mileage, running style, impact forces, and body weight.  The sensor wirelessly transmits the total running impact to a mobile application where the runner can monitor key metrics. When it’s time to replace worn out shoes, the application alerts you and makes recommendations for the optimal next pair of shoes based on your unique running style.  This product could change the standard for running health and injury prevention.  And save me the conversation and the olfactory strain of smelly old shoes.  All the while saving you a visit to see me  when your body breaks down!


The pod sits atop your laces and collects data on various metrics. Learn more at www.shoesenserunning.com

This sensor has great promise and I hope it will increase runners’ sensitivity to replacing worn shoes.  It’s often the first variable I address to make sure it’s not sabotaging my treatment and keeping athletes from running.  Once running athletes replace their worn shoes, the consistently marvel at how good they feel.  I can say with confidence that for many clients, replacing worn shoes is half the injury battle.  I’m personally eager to see what Shoe Sense says abou the durability rating of different shoes based on how they wear over time.  But mostly I like that the sensor gives me yet another reason to go shoe shopping.  I hope you’ll check out Shoe Sense Running and please let me know what you think. In the meantime, please go get new shoes if you’ve run in a pair for over 6 months.  You’ll be glad you did!


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