Most of the recent studies on fast particles deal with the stabilization-destabilization of magnetohydrodynamics modes. Here the authors present another aspect of fast particle resonances in tokamaks and review some recent results on the dynamics of energetic electrons and alpha particles. The interaction between the runaway population and the magnetic ripple is analyzed. The occurrence of an induced radiative slowing down is demonstrated and its potential is assessed. Then, the resonant channeling of alpha particle free energy, to either fast electrons or fast ions, by means of lower hybrid waves is investigated, and the efficiency of this process is analyzed.