“If I was to pick one thing that keeps you injury-free, it’s the concept of rest—getting enough sleep and relaxation and recovery between workouts,” says Norbert Sander, MD. As the founding director of New York’s Preventive and Sports Medicine Center, Sander has treated sports injuries for more than three decades. “You risk injury if you’re running too hard too often or you’re sleep-deprived.”

Dr. Sander is a lifelong runner - and the winner of the 1974 New York City Marathon. “Science backs up how training cycles work,” he says. “You run into problems when you skip the ‘down’ part of the cycle. Don’t be obsessed with doing a particular workout. Frank Shorter once said he never does speed work on tired legs. If the calendar dictates, ‘Today is intervals,’ but you go out and say, ‘I’m beat,’ then you’ve got to adjust that. Because that’s how you can get hurt.”

Multisport coach Scott Cohen agrees. “Our bodies protect us from the continual impact of running by adapting and strengthening themselves. Much of this strength comes from allowing for proper recovery and from cross-training.”

Cohen thinks that “listen to your body” should be the endurance athlete’s mantra. He believes that runners can learn to detect signs of potential injuries early: unusual soreness, localized tenderness in muscles that are stressed by running: “This [awareness] can take time to develop. A gradual progression in mileage—a 10-percent weekly increase, at most—should be a priority if you’re new or returning to running.”