The aim of the project was to investigate how respiratory function is affected by increased gravity (G) and the use of G-protection equipment (anti-G suit (AGS), counter-pressure jerkin (CPJ), positive pressure-breathing). Studies in normogravity were conducted at FOI "s respiration laboratory, Linköping and in hypergravity in the human centrifuge at Karolinska Institutet, Stockholm. Development of equipment and software has been performed to allow measurement and analysis of different physiological variables. The two main issues were: A-Effects on lung function of gravitational forces and pressurization of an AGS; B- Function of CPJ during positive pressure breathing at high G-loads (PBG). Our studies showed that a change in body posture from standing to supine deteriorates ventilation distribution between large lung regions (interregional). Increased G-load (3 G) involved significant effects on lung volumes and increased ventilation inhomogeneity, both interregionally and in the lung periphery where gas exchange takes place (intraregionally). Pressurization of the AGS at 3 G improved interregional but impaired interregional ventilation distribution. Furthermore, the amount of trapped gas increased significantly. Studies of CPJ showed no differences in G-tolerance, G-endurance, or comfort, with or without pressurized AGS, during PBG up to 9 G (see abstract, reference 6).