Chronaxie is the minimum time required for an electric current double the strength of the rheobase to stimulate a muscle or a neuron. Rheobase is the lowest intensity with indefinite pulse duration which just stimulated muscles or nerves. Chronaxie is dependent on the density of voltage-gated sodium channels in the cell, which affect that cell’s excitability. Chronaxie varies across different types of tissue: fast-twitch muscles have a lower chronaxie, slow-twitch muscles have a higher one. Chronaxie is the tissue-excitability parameter thatpermits choice of the optimum stimulus pulse duration for stimulation of any excitable tissue. Chronaxie (c) is the Lapicque descriptor of the stimulus pulse duration for a currentof twice rheobasic (b) strength, which is the threshold currentfor an inf