The specific advice can differ from specialist to specialist. Some, like Dr. Weinstein, say most people can continue with the sport they love although they may need to cut back a bit, running shorter distances or going more slowly. Others say to cross-train at least some of the time and others say the safest thing to do is to cross-train all the time until the pain is gone. You might end up cycling instead of running, or swimming instead of playing tennis. But unless it’s something as serious as a broken bone or a ripped ligament or muscle, stopping altogether may be the worst thing to do.

“We want to keep you moving,” said Dr. William Roberts, a sports medicine specialist at the University of Minnesota and a past president of the American College of Sports Medicine. “Injured tissue heals better if it’s under some sort of stress.”

He and others acknowledge that the advice to keep moving may come as a surprise and that some doctors feel uncomfortable giving it, worried that their patients will do too much, make things worse and then blame their doctor.

“I’m not convinced this is part of every doctor’s training or that everyone is ready to make it part of mainstream medicine,” Dr. Roberts said. “You have to work with athletes a while to figure out how to do it and how to do it well.”

“The easy way out is to say, ‘Don’t exercise,’ ” said Dr. Richard Steadman, an orthopedic surgeon in Vail, Colo., and founder of the Steadman Hawkins Research Foundation, which studies the origins and treatment of sports injuries. That advice, he added, “is safe and you probably will have healing over time.” But, he said, “if the injury is not severe, resting it will probably prolong recovery.”