Implications of sex differences in orthostatic tolerance during exposure to acute artificial gravityFisher, Jason T. (Avtor) Mekjavić, Igor B. (Avtor) Ciuha, Urša (Avtor) artificial gravitycardiovascular responsemicrovascular blood flowhaemodynamicsDevelopment of countermeasures to minimise spaceflight deconditioning is of paramount importance, such as the short-arm human centrifuge (SAHC); however, sex differences in cardiovascular responses should be considered. 20 participants (female = 10, male = 10) conducted an identical centrifugation protocol of 10-min phases of standing (NG), 1Gz centrifugation (1GRF), and 2Gz centrifugation (2GRF). Separated by 10-min each in hot (29.1 ± 0.8 °C) conditions, and either normoxia (PO2 = 133 mmHg) or hypoxia (PO2 = 92 mmHg). Haemodynamics, microvascular blood flow (arm and leg) and temperatures (skin and gastrointestinal) were continuously recorded. At 2GRF, females lasted 2.7 ± 1.6 min less than males. Arm blood flow significantly decreased, and leg blood flow increased, in 2GRF (p > 0.001); with higher female leg blood flow in 2GRF (p = 0.002). 2GRF altered all haemodynamic variables and females exhibited significantly higher heart rate, and lower stroke volume index (p < 0.001). Female participants exhibited greater cardiovascular strain, and encountered pre-syncopal symptoms earlier, during 2GRF. Future research should consider individualised and tolerable gravitational loads.Nature Publishing Group20252026-01-28 14:34:22Neznano27012UDK: 612ISSN pri članku: 2373-8065DOI: 10.1038/s41526-025-00516-6COBISS_ID: 249987331ZDAsl© The Author(s) 2025