In-situ straining experiments on dislocation motion in Ge and Si-5 at% Ge alloy single crystals are performed in a high voltage transmission electron microscope. In comparison with previous results by other methods, the dislocation velocities are found to be enhanced due to a recombination enhancement owing to the excess carrier injection by the electron beam. The reduction in the activation energy of dislocation motion is ascribed to the recombination-assisted kink formation. The kink migration energy is estimated to be 0.7 eV in Ge and 1.5 eV in SiGe.