Low-temperature magnetotransport experiments have been performed on a p-type GaAs/AlxGa1-xAs quantum well. From activation measurements on Shubnikov–de Haas conduction minima it was found that exchange interactions can be of great importance for both odd and even filling factors and strongly influence the observed periodicity. Furthermore, it was found that the temperature dependence of Shubnikov–de Haas oscillations in the low-magnetic-field regime could not be explained within a single-particle model based on a solution of the full Luttinger Hamiltonian in a magnetic field. Numerical simulations of Shubnikov–de Haas spectra, based on a model that treats hole exchange interactions in a simplified manner, show unambiguously that exchange driven enhancement of hole "spin" splittings are extremely important at magnetic fields as low as 1.5 T. Also, the inclusion of a valence-band warping in the calculations is shown to be essential. Qualitatively, most experimental observations could be described within the presented model. Our results imply that, in any hole system, the effective masses obtained from temperature-dependent SdH measurements are to be treated with extreme care as they can deviate from their single-particle value by as much as a factor of 2.