An exercise stand which is constructed of a main frame on which are mounted a leg at each corner. A motor vehicle includes an electrical accessory connected to an electric battery of the vehicle, wherein powering of the accessory is controlled by the above method when the battery is charged and connected to an external generator. The vibrating body has vibrational characteristics in which whether or not a resonant frequency of the torsional vibration and a resonant frequency of a disturbing vibration are equal to each other depends upon a shape-defining parameter for defining a shape of the integral spring extending lengthwise.