Introduction: The anti-G straining maneuver (AGSM) is still an important part of pilot protection for G-induced loss of consciousness. They affect peripheral resistance, chest pressure, baroreceptors and autonomic nervous system activity. In consequence AGSM have the influence on parameters that determine of heart systolic function and left ventricle work. AGSM are combination of muscles tension (MT) and breathing techniques, but up till now it is not known which component affect more the physical aspects of blood circulation and cardiac function. The aim of the study was comparative assessment of changes in selected hemodynamic parameters during classical Valsalva maneuver (VM), MT and AGSM series. Method: 20 healthy, volunteer, pilots were examined. Hemodynamic parameters were recorded by impedance cardiography in rest and during VM, MT and AGSM. Each test last 15 s. Cardiac output (CO) , left ventricle work index (LVWI), pre-ejection period (PEP), left ventricular ejection time (LVET) and Heather index (HI) were measured.Results: means values of parameters in rest, VM, MN and AGSM is shown in table 1In comparison with rest (R), LVET was statistically shorter during VM and MT; CO increase only during MT and AGSM; PEP became shorter during MT and AGSM; LVWI was higher during AGSM and MT and HI was higher only during AGSM. Conclusions: 1. During AGSM series the dynamic changes in preload , afterload and sympathetic activity significally affect parameters of systolic function and left ventricle work. 2. The hemodynamic trend during AGSM similar to MT suggest higher input of muscles tension.