The idea of introducing an electric current into your system may seem distressing. However, electrical shock is commonly used to treat patients experiencing heart conditions such as cardiac arrest. Recently, external electrical stimulation has been substituted for gym time and is used to produce "fake" stimulation of the nerves innervating muscles. This often produces the same effects that may result from an (honest) heavy-duty muscular training program. But why would someone carry a battery and some electrodes with him or even implant these devices into his body to receive these electrical stimulations?