Wearing the right running shoes can mean the difference between safety and injury when you take to the road (or the track). But there’s no one-size-fits-all definition of right—so a type of shoe that’s perfect for your running partner may be totally wrong for you.

Simple safety strategy: “When it’s time to buy a new pair of running shoes, bring your old pair along to the store. Because the wear pattern on the soles is a visual representation of what your foot is doing mechanically, it provides clues that a knowledgeable salesperson can use to fit you with the most appropriate shoe,” said podiatrist Jonathan D. Rose, DPM, coauthor of The Foot Book: A Complete Guide to Healthy Feet. For instance, here’s what it means if your old soles have…

  • Visibly worn treads on the outside edges, with relatively untouched inner edges. You tend to supinate—meaning that your ankles roll outward too much—probably because your high, rigid arches restrict the normal inward movement called pronation. Landing hard on the outer edges of your feet increases your risk for stress fractures. You’ll do best with well-cushioned, highly padded, shock-absorbing running shoes, Dr. Rose said. Avoid styles labeled “stability” or “motion-control”—these would only further encourage supination.
  • Excessive wear on the inner edge of the heels and/or behind the big toes. You tend to overpronate—that is, your ankles roll inward too much—which is likely due to flat arches or excessive rotation at the hips or knees. This increases your risk for various painful inflammatory conditions that affect the heels, ankles and shins. For safety, Dr. Rose recommended a stability shoe (for moderate overpronation) or a motion-control shoe (for severe overpronation)—these provide extra arch support and stabilizing features that limit inward roll.

Where you shop matters, too. “Clerks at discount chains may not be knowledgeable enough to recommend the right shoe, so it’s worth paying a bit extra to buy from a specialty retail store with experienced salespeople,” Dr. Rose said. Some top stores even have a treadmill on site so salespeople can observe your gait firsthand to confirm what they learned from the wear pattern on your old shoes and make the best recommendation for your new pair.