By Erica Moe

What kind of shoe do you have? Do you wear running shoes for every activity?

Consider getting sport-specific shoes if you spend more than three hours per week doing a sport activity. For example, if you play basketball twice a week for 1.5 hours, consider a shoe with ankle support. If you attend cardio classes three times per week for an hour each, you will want lateral support that running shoes may not provide.

How long is too long?

Athletic shoes should be replaced approximately every 500 miles. Type of shoe, type of surface, amount of use and your own biomechanics can impact the life span of your shoe.

Look for the signs. Maybe you no longer feel the cushioning; or have aches in your lower extremities or back. Shoes may stretch over time and not fit correctly any longer. Take a look at your shoes. If you can see obvious wear and tear, it may be time to shop.

Why replace?

Wearing worn out shoes could injure your feet and other body parts, i.e. the foot bone is connected to the ankle bone, etc. Common injuries due to worn out shoes include: shin splints, heel spurs, plantar fascitis and stress fractures. Replacing worn out shoes is on Dr. Stephen Pribut’s list of the top ten ways to avoid running injuries. “It is always cheaper to replace your shoes than to make a visit to the doctor’s office,” he points out.

If your shoes are no longer supporting you, it is time to get fitted at a local specialty shoe store with expertise to watch your running or walking gait. Have your feet measured each time you purchase shoes. Your foot shape and size can change as you age. The American Council on Exercise reminds us that feet can swell up to a half size by the end of the day. It’s a good idea to wear the shoes at least 10 minutes in the store before purchasing.

Components of a shoe

• Last: The template or model upon which the shoe is built. Different manufacturers use different lasts.
• Outer-sole: The outermost part of the sole, which is treaded. On running shoes the tread is designed for straight-ahead motion. Court shoes and cross trainers have their tread optimized for lateral or side-to-side stability.
• Upper: The uppermost part of the shoe. This part encompasses your foot and has the laces.
• Midsole: The portion between the upper and the outer-sole. This area’s major contribution to the shoe is shock absorption. Ethylene vinyl acetate and polyurethane midsoles are composed of foam materials. These materials, after a certain amount of use, will no longer absorb the impact of each compression. Therefore, shoes will lose their shock absorption over time.
• Sockliner: This is the liner inside the shoe that has a bit of an arch and usually some shock-absorbing material incorporated into it.
• Counter: A rigid piece surrounding the heel that provides some stability.

Interested in learning more? American Association of Podiatric Sports Medicine: aapsm.org.

—Erica Moe is an ACSM certified exercise physiologist who writes on behalf of the Mission Valley YMCA, where she is a fitness director.