  Based on SPH simulations, we quantify the geometrical distortion effect due
to tidal and rotational forces on polytropic secondaries in semi-detached
binaries. The main effect is an expansion of the polytropic star, with an
effect on the radius of $\sim$ 5%-12%, depending on the polytropic index and
the mass ratio. We apply such distortion effects to the secular evolution of
secondaries in cataclysmic variable systems. We focus on systems below the 2-3h
period gap and that approach the minimum period. We find a significant increase
of the predicted minimum period ($\sim$ 4% if changes in the secondary's
thermal relaxation are approximately taken into account). Though an
improvement, the effect is not big enough to solve the mismatch between
predicted and observed minimum period at 80 min.
