Physiological Responses to Four Different Baseline Accelerations on a Human Centrifuge

INTRODUCTION: Human centrifuges use baseline acceleration levels between high-G exposures to optimize mechanical performance and minimize motion sickness. This trial assessed the cardiovascular changes associated with different centrifuge baselines to assess their impact on trials and training. METHODS: A total of 10 subjects (1 female, median age: 35, age range: 27 yr) underwent 2-min exposures to +1.2, +1.4, +1.6, and +1.8 Gz on a human centrifuge, with 5 min at +1 Gz between runs. Cardiovascular variables were assessed via the volume-clamp method and 3-lead electrocardiogram. Blood volume change in the abdomen, thigh, knee, and calf were measured via impedance plethysmography. RESULTS: There was an interaction between all +Gz baseline levels and cardiac output, stroke volume, heart rate, and total peripheral resistance. There was an interaction with mean arterial and diastolic blood pressure at both heart and head level, and with systolic blood pressure at head level only. When compared to +1 Gz, the highest baseline tested of +1.8 Gz resulted in increases in heart-level diastolic pressure (14 ± 8%), total peripheral resistance (31 ± 19%), and heart rate (12 ± 8%), with decreases in cardiac output (-17 ± 9%), stroke volume (-27 ± 4%), and head-level mean arterial pressure (41 ± 9%). Decreases in impedance were greater in the abdomen and thigh at higher +Gz baselines. DISCUSSION: The measured response when transitioning from +1 Gz to +1.6 and +1.8 Gz was similar to that previously reported on transition from supine to standing. This response should be considered when selecting baselines, particularly for cardiovascular research. Britton JK, Green NDC, Harridge SDR, Peters AG, Thornton-White CG, Pollock RD. Physiological responses to four different baseline accelerations on a human centrifuge. Aerosp Med Hum Perform. 2026; 97(2):75-83.