When you rip, tear, sprain or break something, it needs to be immobilized, not stretched, kneaded, heated or worked. A large number of patients (and some trainers) mistakenly take dysfunction as a sign of needing more exercise. So they recommend overusing athletic injuries, like muscle tears and stress fractures, which prolongs pain and delays healing for months and months. A good rule of thumb: no stretching or hard work until tenderness (pain when you push on the muscle or joint) is gone.