ATLANTA, Georgia (CNN) -- -- Julie Beverly runs about 20 miles a week. While her workouts are helping to tone her body, they're also wearing down the soles of her sneakers. "The shoes are starting to bow on the sides because they're so old," says Beverly. "Actually, they're making the back of my ankle hurt."
Athletes should keep track of their mileage and replace their workout shoes every 250 to 500 miles.
Beverly isn't alone in complaining of foot, heel or leg pain. Atlanta, Georgia, podiatrist Perry Julien says, "We estimate that 20 percent of the people that come into our office with an injury are there because of their shoes. Either they're worn out or they're just incorrect for their foot type."
Running shoes don't last forever, the doctor says. He recommends that athletes keep track of their mileage and replace their workout shoes every 250 to 500 miles. For someone who runs 20 miles a week, that could mean new shoes as often as every three months, but probably about every six months for sure.
Dr. Julien also recommends that people mark their shoes with the date of purchase to keep precise track of the age. "A date or knowing how much you run on it is better than looking at them," he says.
"Often times when a shoe wears down, it wears down in the mid-sole, and you can't see that wear," he says, "but then you lose the support and the cushioning."
Julien tells his patients to buy their running shoes from a store with experienced sales personnel. They can help determine the right style of shoe for your foot.
Beverly, 31, did just that at Phidippides, a running-shoe specialty store near her home in Atlanta. She spent close to an hour with Gregory Sheats, a sales clerk with 26 years of experience.
"We evaluate her foot by using a diagnostic shoe, and then we can determine the foot function and we'll know which characteristics we'll either be compensating for or complementing," Sheats explains. Watch Health Minute for more on picking the right running shoe »
Sheats determined that Beverly's feet roll in when she walks or runs. He recommended a shoe that will center her feet and neutralize the roll. Beverly began trying on many styles and brands of sneakers. She even ran around the store before settling on what she called the perfect pair.
Julien suggests buying a running shoe that is one-half to 1˝ sizes bigger than everyday footwear.
Be sure to wear a sock with the same thickness you would use for running. Julien says cotton socks can cause blisters. "Cotton tends not to wick away moisture, so using an acrylic blend sock or one of the newer models that wick away moisture will help keep the feet drier."
When it comes to breaking in new sneakers, Julien prefers that runners do it gradually to avoid blisters and other foot complaints, "You really should walk in them for a few days. Let them break in slightly, and then start running a few miles."
Beverly's old sneakers were in such bad shape, she vowed never to wear them again and walked out of the store sporting the new pair. She paid about $100 for the shoes but says, "It's a small price to pay for your ankles and legs and to be able to run without pain." E-mail to a friend
Judy Fortin is a correspondent with CNN Medical News.
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