It is a report on our running joint work with V. Chernousov and A. Pianzola. Let R be the Laurent polynomial ring in n variables over a field k of characteristic 0. We are interested in loop semisimple simply connected groups G/R, that is a certain kind of reductive group schemes related to (multi)-loop Lie algebras. When such a group is isotropic, we shall investigate the question of its generation by one parameter additive subgroups, with special attention to the nullity one case.