Since their discovery, Luminous and Ultraluminous Infrared Galaxies (U/LIRGs) have been the subject of numerous studies due to their characteristically intense star formation rate (SFR). These objects are the perfect laboratory to study in detail the physical and dynamical processes that govern the creation of stars from gas reservoirs and are therefore critical for the evolution of galaxies. Furthermore, although these galaxies are not common in the local Universe, they are the dominant population to the energy density at z>1. Understanding the behaviour of gas and stars in these objects is therefore critical to our knowledge of what the Universe was like more than 8 billion years ago. Gas kinematic studies in these objects have revealed that their behaviour encompasses a wide range of dynamical states, from those dominated by the rotating-disc motions to much more complex ones driven by gravitational interaction processes. It is also worth noting that the intense starbursts and the presence of active galactic nuclei (AGN) in these objects yields a scenario where the presence of gas ejections, in any of their phases, is not uncommon. In this scenario, the stellar component is really relevant, since stars area better tracer of the gravitational potential as they are less reactive to local events that may perturb their kinematics. However, the stellar kinematics of these objects remains largely unknown, partly due to the difficulty of obtaining a signal-to-noise value (S/N) high enough to observe the stellar continuum, and has only been studied for a small number of objects, generally from the integrated and/or nuclear spectra...