The method is for use in a part of a mammal having one or more tender points and comprises a dministering a fluid, by a needleless, pressure-based injector, to substantially all of the tender points in the part. The volume of the fluid that is administered to each of the tender points can be about 0.5 cc. The operating pressure of the injector can be about 150 psig. The fluid can be a local anesthetic such as ropivacaine.
