You love your running shoes. They've carried you up Tantalus and around the Ala Wai Canal. They're dirty and beat up and you love them, but you're worried that they don't give you the cushion and support you need.
So how do you know when it's time to break up with your running shoes? There are lots of different ways to determine when to give your old shoes the “heave ho.”
500 miles. I was taught in podiatry school that the average lifespan of a running shoe is 500 miles of use. After that time, the midsoles are usually broken down and the shoes have lost most of their shock absorption.
One year versus six months. For diehard runners who are tough on their shoes, a set timeframe for replacement is a way to prevent injuries. Distance runners or heavy runners will need to replace their shoes earlier rather than later. One way to prolong the life of your running shoes is to alternate them with another pair. This allows the shoes to dry out and regain resiliency on their "days off."
When the uppers have holes. Some runners will change their shoes when their uppers have holes, reasoning that the midsoles are probably just as damaged.
When the shoes tilt. Most runners land on the outsides of their heels and roll medially onto the balls of their feet. This causes the shoes to wear on the outsides of the heels and tilt laterally. I recommend replacement of the shoes if the shoes are inverted more than 5 degrees from vertical. Worn-out, tilted shoes can cause ankle sprains, tendinitis problems, or worse yet, ankle fractures.
When the wear pattern exposes the midsole. The normal wear on the outside of the heels will present as a thinning of the black rubberized material of the outsole. When the layer of black material is completely worn away and the lighter-colored midsole material is exposed, the shoe is worn out and needs replacement.
When the “bounce” is gone. When the shoe is new, the midsoles are "springy," but as the shoes are worn, the air cells in the midsole material crush and compress on a microscopic level and the shoes start to feel "dead." When the spring is gone, it's a good time to replace the shoes. One caution about using this method: the loss of bounce is gradual and you may not realize it happened until the shoes are too far gone.
When it hurts to wear the shoes. I know it seems obvious, but if you get hurt using your shoes when you didn't get hurt before, chances are the shoes are worn-out and need replacing. Don't wait until the pain is unbearable before you change your shoes. Realize that the minor ache from the injury will get worse over time due to the repetitive trauma.
I recommend these methods and they all work. Use whichever method occurs first or works for you. If you aren't sure your shoes need replacing, contact your podiatrist or sports medicine specialist.
I know it's difficult to retire your beloved shoes, but maybe you can still wear them while pulling weeds.
Dr. David Y.S. Yee is a board-certified podiatrist in private practice in Honolulu. He is on the medical staff of Straub Clinic and Hospital. His areas of practice interest include diabetic foot care, shoe fit and design, patient education, orthotic therapy and extracorporeal pulse activation therapy (EPAT).