Apparatus and methods for therapeutically treating bone fractures, osteopenia, osteoporosis, or other tissue conditions. A platform supports a body to be treated. An oscillator is positioned within the platform and is configured to impart an oscillating force on the body. A capacitor assembly is positioned adjacent the platform for automatically determining the mass of the body being supported on the platform. Once the mass of the body is determined, an amplitude of the frequency of the oscillating force is adjusted to provide a desired therapeutic treatment to the patient. Also, the capacitor assembly is configured to turn the oscillator on and off as a function of whether or not a body is being supported on the platform.