Whether you're an avid marathoner or simply enjoy the occasional jog, it's important to know when to change your shoes. If you keep running on worn-down soles, you risk incurring injuries that warrant an otherwise avoidable trip to the foot doctor. There is no uniform answer to the question of when to replace your sneakers, as it depends on everything from how much you run to the condition of your feet. Use this guide to determine if it's time for a new pair.

A Guide to Replacing Your Sneakers
General Advice
The prevailing wisdom is that you should change shoes about every 350 to 500 miles. For some people, this equates to buying a new pair every six months to a year. Some write down the d...