Many runners are in the shoe rotation habit. They run in their favorite running shoes until they are worn out and then instead of throwing them away they wear them as casual shoes because they still look good. To use a Nike slogan, Just Don’t Do It. When we are running our shoes compress & absorb shock, they keep our leg aligned & stable, and keep us from bruising our toes and heals. When we’re walking, same thing.
You must have figured out by now that running in old or worn out shoes can lead to an increase in running injuries because they lose stability and shock absorption capacity over time. That added stress to the feet and legs increases and can lead to overuse injury. Walking in those worn out shoes can do the same thing, “miles is miles”.
The most common error made in the are my shoes worn out equation is the sight test. We turn them over and look at the tread pattern and search for sole wear, we look at the uppers and see if there are any holes, and if everything looks fine, we’re good to go. Weakness in this test comes from being unable to get a good look at the midsole. The midsole layer of a shoe provides the cushioning and stability. It will usually wear out miles before the rest of the shoe will show any signs of wear. When a midsole wears out the shoe looses functional stability and cushioning, which can lead to increased stress and injury risk.
Heavier runners will need to replace their shoes more often because of extra compaction. Lighter runners will get more mileage because they are not producing the same compression rates. It is recommended that running shoes be replaced between 350-550 miles. There are some variables, for example, if you run exclusively on the roads hard surface, your shoes will wear out faster than trail running. If they feel beat, you know you have an excess of 350 miles on them, and you are beginning to feel foot, ankle or knee pain, they’re probably worn out even if they don’t look like it. If they’re worn out, throw them away. Walking in them is as bad for you as running in them.