If the shoe fits ... Published March 4, 2009 81st Surgical Operation Squadron KEESLER AIR FORCE BASE, BILOXI, MISS. -- Wearing proper running shoes can help prevent injuries, such as patellofemoral pain syndrome, shin splints and fasciitis. Feet are not all created alike. Some have low arches, others high arches -- few have normal arches. Normally, feet pronate (roll inward) slightly for shock absorption. Depending on the foot type, feet may pronate sufficiently, too much or too little. About 60 percent of the population are overpronators. They tend to have low arches, which require the feet to excessively pronate when the feet hit the ground. Motion-control shoes are best for moderate to severe overpronators as well as larger or heavier runners who need more support. The inside sole of the shoe is made of denser materials that prevent overpronation. Underpronators make up 30 percent of the population. They usually have high arches and tend to run on the outside of their feet. Due to decreased pronation, their feet have poor shock absorption. These runners should choose cushioned shoes. Cushioned shoes have maximum midsole cushioning and minimum arch stability. Roughly 10 percent of the population have normal arches, and their feet pronate slightly for shock absorption. Runners with normal arches and those with mild to moderate overpronation should wear stability shoes. Stability shoes provide arch support and midsole cushioning. Here are some tips for buying new running shoes: Look for shoes made specifically for running. Shop at the end of the day or work shift when feet have had time to expand. Have feet measured since they tend to widen and lengthen with age and activity. Wear athletic socks when trying on shoes. Bring orthotics if worn. Try shoes on both feet. Make sure there is a half inch from the longest toe to the front end of the shoe. Ask for a wider shoe if the one tried is too narrow. Jog in the shoe before buying them. Go for fit and comfort, not solely on looks. Remember that running shoes don't last as long you may think. Running shoes lose their shock absorbing qualities between 300 and 500 miles. Runners should follow these general guidelines for shoe use and replacement: Those who run less than 25 miles a week, replace shoes every four months. Those who run more than 25 miles a week, replace shoes every three months or 300-500 miles. Shoes may also be replaced based on signs of wear and running injuries. To help shoes last longer: Use running shoes only for running. Try alternating two pair of running shoes. Avoid storing shoes near a heat source or in direct sunlight as heat can deform shoes. Hand-wash shoes in cold soapy water and air dry. Finally, runners need to include warming up, stretching, cooling down, cross training, adequate rest and a gradual increase in mileage in their practice of injury prevention. Wearing proper shoes alone won't prevent injury. Anyone suffering an unresolving running injury should stop running, see their primary care manager and ask how physical therapy can improve the condition.