| Introduction. Physiological tolerance of +Gz during successive +Gz exposures has not been determined. The objective was to compare, in humans, +Gz tolerance over a brief set of repeated +Gz exposures with that of the first +Gz exposure. Methods. Subjects rode the centrifuge performing simulated air combat manoeuvring (SACM) composed of 10 successive, rapid-onset, +Gz cycles (C1--C10) with brief pause periods at +1.4 Gz. For altered SACM characteristics, 4 profiles with combinations of short or long duration +Gz plateaus (8s, 20s) and short or long duration +Gz pauses (1s, 15s) were investigated. Results. Lowest head-level systolic blood pressure and vision quality during each +Gz exposure improved over the course of the +Gz cycles, this increase being greater for the SACMs with pause durations of 1s between cycles. Conclusion. There was improved +Gz tolerance, greater for the short pause duration profiles, during a set of repeated +Gz exposures. |
