Doctors Explain When to Replace Worn-Out Running Shoes

Running shoes may look fine on the outside long after they've stopped doing their job, doctors say, and continuing to run in worn-out shoes can leave feet, knees and joints unsupported, raising the risk of aches, pains and injuries.

"In general, a running shoe should last somewhere between 300 and 500 miles," said Dr. Dietmar Walter, head of podiatry at Stride Soles, a custom orthotics company. "However, the exact length depends on your weight, running surface and of course the shoe type."

Walter said body weight can dramatically affect how quickly a shoe wears out. "I see many patients over 200 pounds only last 200 miles in their shoes, while someone under 140 pounds might last over 550 miles," he said — a gap of more than 350 miles between the two groups. Running surface matters too: treadmills tend to be gentler on shoes than pavement or concrete, which wear down cushioning faster.

Mileage isn't the only signal. "A good sign that your shoes need replacing is if you are starting to get unexpected aches and pains — like achilles tendonitis, shin splints or plantar fascia pain," said Dr. Milica McDowell, a doctor of physical therapy and co-author of "Walk: Rediscover the Most Natural Way to Boost Your Health and Longevity — One Step at a Time."

Walter recommends checking three parts of the shoe for visible wear. First, the midsole: if it looks compressed, has grooves or ridges, or shows uneven wear, it's likely time for a new pair. Second, the inside back of the shoe where the Achilles rests — if that area is torn or missing material, the foot is no longer held securely. Third, the bottom of the shoe: if foam is visible through worn rubber or there are bald spots with no tread, replacement is overdue.

Doctors say paying attention to how shoes feel matters as much as counting miles, since breakdown happens gradually and can go unnoticed until pain sets in.