Figure 1.

Schematic of a participant positioned in 45°HDT in the custom‐built integrated tilt and LBNP apparatus. The participant was instrumented with a mouthpiece and nose clip (to sample P_ETCO ₂), Finometer (for monitoring beat‐by‐beat blood pressure), ECG leads (for monitoring HR), and TCD (for monitoring MCAv and PCAv). The LBNP chamber was secured to a custom‐built frame on an axle, and was connected to an industrial shop‐vacuum to generate negative pressure, and a digital manometer was used to monitor pressure within the chamber. The participant was secured inside the chamber with ankle restraints, and they were sealed within the chamber by means of a kayak spray skirt. ECG, electrocardiogram; HR, heart rate; LBNP, lower body negative pressure; PCA, posterior cerebral artery.