In slowly rotating stars, the coupling of helium settling and meridional circulation leads to a particular hydrodynamical process which was not introduced in previous computations of abundance variations. The μ-gradients induced by element settling can lead to a quasi-paralysis stage in which the efficiencies of both the meridional circulation and the microscopic diffusion are strongly reduced. Such an effect was studied in the eighties for nuclear-induced μ-gradients by Mestel et al., who called it “creeping paralysis”. Below convective zones, this process has important consequences. Here we discuss the case of the halo stars and the sun.