The protocol we propose in this document presents minimal risks for our potential subjects, while has the potential to produce important contributions. The cardiovascular parameters we intend to analyse are: blood pressure, heart rate and leg blood volume. These signals will be acquired non-invasively and with minimal risks. Leg exercises will be performed by means of a stepping device (MARCOS) previously developed in our Lab. MARCOS enables to vary the resistance applied against knee-extension movements, and therefore it allows a systematic evaluation of different exercise intensities. Finally, microgravity conditions can be easily emulated by letting the subjects lay on a tilted platform with head-down (i.e. head-down bed rest - HDBR, or head-down tilt - HDT) during the exercise sessions, thus inducing a shift of body fluid toward the thorax. The most effective inclination angle has proved to be as low as -6°, thus constituting only minimal risks for the subjects. In practice, subjects will comfortably lay on the negatively tilted platform and will perform stepping at different intensities while their cardiovascular parameters are being monitored and recorded in encrypted form for subsequent analysis.