Your lucky pair of running shoes might not be so charmed, after all. According to a new study from the Sports Medicine Research Laboratory in Luxembourg, running day after day in the same sneaks can lead to results-wrecking injuries.
For the study, researchers gathered intel on the running habits, injury rates, shoe usage, and cross-training routines of 264 recreational runners. During the 22-week study, 87 of the subjects suffered from at least one running-related injury that prevented them from logging miles for one day or more. While their running frequency, speed, and mileage varied, the injured runners tended to have one thing in common: They always ran in the same pair of shoes.
MORE: 6 Common Running Injuries and How to Cure Them
Meanwhile, the runners who rotated between multiple pairs of running shoes (3.6 sets of kicks, on average) during the study had a 39 percent lower risk of injury. Researchers say the protective effect is due to mixing up the impact running has on your body. Shoe design influences your stride and form, so if your shoes vary, so does the strain put on any given joint or tissue. Plus, as your shoes wear out, your form could change in response to the decreased cushioning. Another interesting finding: runners who participated in other sports were less likely to get injured. And, likewise, every sport and workout stresses your body differently, explaining why runners who reported more cross-training also had a lower risk of injury.
While running in the same pair of shoes—especially if they’re well-fitting—doesn’t guarantee a run-ending injury, if you’re prone to lower-body pains post-run, it might be time to add to your running shoe collection. After all, a little shoe shopping never hurt anyone. Check out our list of the 7 best running shoes for women.