Abstract <p>The paper examines the effect of breathing with additional negative pressure during inhalation (NPBin, –20 cm H₂O) on breathing and gas exchange in a healthy person in the antiorthostatic position (‒8° relative to the horizontal). It was found that with NPBin, the respiratory rate significantly decreased. Median (M), 1st (Q1) and 3rd (Q3) quartiles were: before NPBin M = 16.4 min^–1, Q1 = 13.4 min^–1 and Q3 = 18.5&#xa0;min^–1; during NPBin M = 6.9 min^–1, Q1 = 5.7 min^–1 and Q3 = 10.2 min^–1. In individual volunteers, the respiratory rate decreased to 4−5 cycles per minute. With NPBin, tidal volume increased: before NPBin M = 0.50 L, Q1 = 0.43 L, Q3 = 0.56 L; during NPBin M = 0.66 L, Q1 = 0.56 L, Q3 = 1.07 L. Changes in respiratory rate and tidal volume were accompanied by a decrease in the minute volume: before NPBin M = 9.6 L/min, Q1 = 7.8 L/min, Q3 = 10.0 L/min; during NPBin M = 6.7 L/min, Q1 = 5.7 L/min, Q3 = 8.2&#xa0;L/min. Also, with NPBin, the respiratory exchange ratio increased: before NPBin M = 0.777, Q1 = 0.722, Q3 = 0.817; during NPBin M = 0.875, Q1 = 0.818, Q3 = 0.916. Despite the decrease in minute ventilation, there are signs of СО₂ washout from the body tissues during NPBin, which indirectly indicates an increase in the efficiency of gas exchange in the lungs during NPBin.</p>