I believe that healing can only occur from within. Ultimately, there is not another person, whether doctor, chiropractor, physical therapist, or any of the alternative medical practitioners, who can heal.
However, all of those in the so-called healing professions can create a more favorable environment in which self-healing can occur.
Any modality that brings the body into a more aligned or better status can create such environment. Exercise is clearly among those modalities, and it is therefore appropriate to call exercise medicine.
However, whether exercise creates a better or worse environment is dose-dependent. A little goes a long way, and more is not always better. We all know of people who exercise so compulsively that they are creating a negative internal environment, and rather than improving their health, they are compromising it.