We have performed magneto-absorption measurements in p-Ge under intense crossed electric and magnetic fields. The results are interpreted with the coupled-band (Pidgeon and Brown) model. By comparison with the parabolic (Luttinger) model we show that non-parabolic effects, caused by the influence of the spin-orbit split-off band and the conduction band on the valence bands, have to be taken into account to explain the observed spectra.