Purpose: This article focuses on the effect of gravity on cardiorespiratory responses at rest and exercise compared in three positions Current knowledge and key points: Low blood negative pressure is in relation to the body position and gravity. This process has not been the subject of several studies. But in the few studies that there is, we noticed that in all experiments, there are cardiorespiratory responses resulting from the reduction of the effect of gravity or following a change of position body (supine / uper) and these responses are expressed in different ways. Future prospects and projects: We suppose that the accumulation of blood in the lower limbs either by simple gravity ( low blood negative pressure), or by applying negative pressure through a decompression chamber, generates ventilatory or cardiac responses, or both on different ways depending on the body position