PUBLISHED 10/28/2008 LAST UPDATED 10/28/2008

RUNNER'S WORLD MAGAZINE

When is it time to retire my running shoes?—Ken Becker, Phoenix
Between 300 and 500 miles. Why the range? Because how quickly a shoe wears depends on you. If you land hard on your heels with each stride, for example, you're going to wear through shoes more quickly than more efficient runners. Go by feel. If after a normal run your legs feel as if the shoes aren't providing you adequate protection, they probably aren't. Give your legs a week to make sure it's really the shoes and you're not just tired. If the shoes still feel dead, replace them. We can tell you that the vast majority of runners replace their shoes too late. When you can see white midsole material poking through the outsole or when the sole under the heel looks crushed, the shoes are long past their prime.

I'm new to the sport, and when I went to buy my running shoes, the local running-store owner explained that training in two or three different shoe models is better for your feet. I bought her story and walked out with two different pairs. Any truth to this?—Rachel Setton, Brooklyn
Good advice, but the up-front cost can seem pretty high. Running in more than one pair will help your biomechanics adapt ever so slightly to each shoe. These adaptations are a good thing because they help prevent overuse injuries. In addition, midsole foam requires as long as 24 hours to fully recover from a run. So if you run at night and then need to get an early workout in the next morning, a different pair will give your body more protection.

After a few tours as an Army fitness trainer stationed in Iraq, I've developed plantar fasciitis. I am a high-arched runner, so what should I look for in a shoe to help curb the pain?—Staff Sgt. James Moore
You should run in neutral-cushioned shoes, since your foot doesn't roll inward enough at footstrike. Adding an aftermarket insole to your shoes will help distribute the pressure and curb your plantar pain. Or try a heel lift, such as Spenco Gel heel cups, which takes some pressure off your plantar fascia by shortening the length your calf has to stretch. Sadly, rest and ice—two things undoubtedly in short supply in Iraq—are key to getting over plantar fasciitis.

Does the surface you run on affect how your shoes break down?—Chris Kuemple, Spring, Texas
Road running will make your shoes wear faster than trail running, for sure, but the way
you run is an even bigger factor. A 200-pound heavy heel-striker who runs exclusively on trails will most likely wear out his shoes well before a 100-pound biomechanically efficient road runner. If you're worried that your shoes are ready for retirement, take a close look at them. If the upper appears pulled or stretched so that the foot is sliding off the midsole, or the grooves on the outsole are worn smooth, it's time for new running shoes.

I notice that during long runs in my motion-control shoes, the balls of my feet hurt. Does this have anything to do with my shoes, my gait, aging, or all of the above?—Aidan Lee, Brentwood, Tennessee
As we age, the natural cushioning of the foot starts to lose its resiliency, which means
shoes with good cushioning are especially important for older runners. To address your sore feet, look for a shoe with good support but better RW Shoe Lab cushioning scores. If you're lighter weight (under 160 pounds), consider moving from a motion-control to a stability model.

The wet test confirms I have flat feet, but my shoes wear along the outside edges. Also, I experience pain along the outside of my knee eight to nine miles into my runs. What type of shoe should I wear?—Bill Ritz, Salinas, California
Chances are your shoe's giving you too much support or you're running in worn-out trainers that are stressing your iliotibial band (ITB). Either way, you're supinating, which means your foot is not rolling inward enough at footstrike. To determine the type of shoe you need, go to a specialty running store to get feedback on your gait. You're likely one of the few runners with flat feet who do not overpronate and need a less-supportive shoe.

Is there any harm in someone with normal arches wearing motion-control shoes?—Joseph Rose, Modesto, California
It depends how much you weigh and how much you pronate. If you weigh less than 140 pounds (120 pounds for women) and overpronate, you'll get plenty of support in a moderate stability shoe. If you weigh 160 to 180 pounds (140 to 160 pounds for women) and overpronate, then go with motion-control shoes. Bigger runners who wear stability shoes will not get the support they need and can actually bottom out the cushioning, negating the shoe's ability to protect the foot from impact.

My shoes wear along the outside, and I have low arches. What type of shoe should I wear?—Michelle "Mimi" Brice, Hayward, California
If that wear is in the heel only, you're one of the 80 percent of runners who are heel-strikers, which means your shoes should offer plenty of impact protection in the heel. Just keep in mind that women often see wear along the outer edge of their shoes because of the greater Q-angle (quadriceps angle) from the hip down to the knee. Shoes with a durable outsole material like carbon rubber will help minimize the wear. Because you have low arches, we recommend going with a more supportive shoe.

I have flat feet, and my arches always get sore after long runs. Why is this, and how can I stop the pain?—Lynne Wekerle, Cincinnati
You most likely have either post-tibial tendonitis or plantar fasciitis. Oftentimes, injuries to the post-tibial tendon are seen just above the ankle, so we're thinking it's plantar fasciitis. We recommend getting properly fitted into a supportive shoe by a specialty running shop. To help the plantar fascia heal, wear shoes with plenty of support even when you're not running, and stretch and massage your arches when you get up in the morning as well as before and after you run. If the pain persists or gets worse, see a sports-medicine doctor.