Sunday, April 14, 2013

Time for New Shoes?

You’ve finally found the perfect pair of running shoes. They fit and feel wonderful. You feel as if you can run forever in them, but they are now starting to show some wear. Is it time toss your favorite shoes and get a new pair?

There are several things to consider when deciding if your athletic shoes need to be replaced. First, how much has the shoe been used? For high-impact activities such as basketball or tennis, shoes should be replaced after roughly 60 hours of use. A simple guideline for running shoes is to change them every 300-500 miles, but there are many factors than can shorten or extend the life of a shoe. For example, a petite runner will have less wear than a heavy runner. The type of running surface can also make a difference as a soft trail will result in less wear than a concrete sidewalk.

Next, check for signs of wear on the outsole. Place your shoes on a flat surface and examine them from behind. Excessive wear may cause the shoe to tilt to one side. If the heels are not perpendicular to the ground, the shoes need to be replaced. For most heel-striking runners, a normal wear pattern is on the outside corner of the heel. If one typically runs on a road or track with a cant (cross slope), an asymmetric wear pattern may develop. A significant asymmetry should be evaluated by a podiatrist as it may be caused by an issue that may be improved through the use of a custom orthotic. 

Finally, it is important to know that the cushioning and support of a shoe will eventually wear down, even if the visible exterior remains in good condition. Athletic shoe midsoles are typically made of EVA which is a compressible material that loses its shock absorptive capabilities with prolonged use. Other factors can speed the degradation of EVA such as high heat or UV light. Loss of cushioning can lead to injuries such as stress fractures or shin splints. Another part of the shoe that can wear out is the upper which holds the shoe onto the foot. This supportive portion of the shoe can become over-stretched with use. When this occurs, the foot has more room to move inside the shoe which can lead to injuries and sprains. 

Good shoes are important in all activities as they provide support, stability, and shock absorption. With continued use, the loss of these protective functions can potentially lead to overuse injuries of the foot and leg such as plantar fasciitis, stress fractures, ankle sprains, and shin splints. The decision to replace your shoes depends on several factors, but if your shoes appear worn, it is time for new shoes.

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