Increasing leg blood volume during head-down tilt by performing physical exercises, a preliminary study

Performing physical exercises is one of the more established countermeasures against cardiovascular deconditioning during space flights. However, a systematic evaluation of the physiological effects of this training in microgravity conditions is still lacking. This manuscript is a first step towards such an assessment. Thirteen male voluntary subjects performed leg press exercises in a microgravity-like condition (head-down tilt). We observed systematic changes in the cardiovascular parameters as an after effects of the exercises, with an increase of leg blood volume, heart rate and pulse blood pressure, and a decrease of diastolic, systolic and mean arterial pressure. Such variations were statistically significant with respect to the values observed at baseline (before the exercise), however they were only transient. Thus, cycles of training and resting periods may be necessary to keep the state of the cardiovascular system obtained after exercises.