member, or friend, or colleague who’s always worrying about the toll running is taking on your knees, hips, and back. You might even be worried yourself. We all know a few one-time runners forced to become swimmers, cyclists, or power-walkers. We wonder
therapist and biomechanist Irene Davis from the University of Delaware's Running Injury Clinic. "Your threshold could be at 10 miles a week, or 100, but once you exceed it, you get injured." Various studies have identified injury thresholds at 11, 25, and 40
