The experimental observation of the association of the internal heat transport barriers in tokamaks with rational q surfaces is an open problem. Often the mechanism invoked for the onset of an ITB relies on the reduction of turbulence by a local increase of the E×B velocity shear. In this work we present in some detail the analysis of the possible role of an externally applied electrodynamic torque, resonant on a rational surface and give an interpretation of some JET experiments.