As a runner, you know that those comfortable running shoes you love so much are like an old friend. You feel secure and happy when they're on your feet, and they've probably traveled with you through miles of memorable runs. But the time will come when the wear and tear will force you to part company with those old pals and buy new running shoes.
The general rule of thumb is that you should replace running shoes somewhere between 350 and 550 miles, depending on your body weight, the surface on which you usually run and your running style. Lighter runners might be able to wait until close to the 550 mark to shop for on a new pair, while heavier runners might wear down cushioning, tread and support material faster. If you wear running flats, replace them between 125 and 250 miles -- flats are not as durable as running shoes and they wear out faster. It's a good idea to log your miles to keep track of how far your shoes have carried you -- this will help you determine when it's time to buy a new pair.
If you have a hard time keeping track of your miles, use a time frame as a good indicator of when it's time to buy new running shoes. The general consensus is that you shouldn't use a pair of running shoes any longer than six months if you run four days a week. If you run anywhere from three to five miles a day, four days a week, you'll be putting in approximately 300 to 500 miles every six months. If you run daily or more than four days a week, you'll need to replace your shoes sooner than six months. Obviously, runners who don't run far or as consistently can wait a few months longer. If you wear running flats on a regular basis, replace your flats between three to six months depending on your often you wear them each week.
Put your shoes on a table and look at them to see how worn they are. If they lean to one side, the mid-sole or arch is probably worn out. In addition, check the tread. Look for spots in the tread that are worn down from repeated pounding of the pavement or trail.
One good way to know you need new shoes is if you feel aches or pains in your low back, knees or ankles. Muscle fatigue and shin splints are other warning signs that your shoes are worn and not giving you the shock absorption you need. Running shoes lose their stability, support and shock absorption capacity after many miles on the road. You risk injury if you continue to run in worn-out shoes.
One way to avoid having shoes that are too new or shoes that are too worn out is to have at least two pairs of running shoes, and alternate them with each run. This lets you extend the life of both, and it helps you avoid injury while still having comfortable and supportive shoes.