Reduced pressure in extended coverage anti-G-trousers with assisted pressure breathing

Six Swedish Air Force pilots and two Armstrong Laboratory subjects volunteered for this study to determine whether reduced pressure in extended coverage anti-G trousers (ECT), in combination with positive pressure breathing for G protection, affected +Gz tolerance. Group mean gradual onset run (GOR) time for the low pressure schedule (0.8 psig.G-1) was significantly different from the other two conditions (1.1, 1.5 psig.G-1)--84.1, 95.6, and 94.1 s, respectively. Group mean simulated aerial combat maneuver (SACM) times statistically differed between the low and middle pressure rates compared to the highest pressure schedule--147.6, 164.8 and 232.3 s, respectively. SACM heart rate (HR) responses for the +9 Gz plateaus were not statistically different among conditions. However, +5 Gz HR's were lower for the highest pressure condition. Similarities were identified between the middle and high pressurization conditions for GOR. However, reducing pressure in the ECT during SACM exposures was not supported by these data.