When should you replace running shoes?

Expert insight: 

The cushioning in running shoes, which absorbs the shock and impact of each step, breaks down every time you wear them. The less cushioning there is, the less effective your pair will be at protecting your joints from issues like runner’s knee and shin splints, says New York City-based Precision Run coach Elizabeth Corkum. 

If you wear light shoes built for speed, you should replace them every 300 to 400 miles. More supportive pairs might last 500, she notes. 

But people often have too narrow a definition of mileage, counting only those they log during actual runs, Corkum adds. If you wear your sneakers to the grocery store, when you lift, or during group fitness classes, you’ll have to buy a new pair at least every three months.

The bottom line: 

Corkum suggests designating one pair of shoes for errands and in-club workouts and a second pair solely for running. Moisture from sweat causes the cushioning to break down even faster. To combat this, remove the insoles after each wear and let everything air dry.