Figure 4.
Boxes show values of middle cerebral vein velocity preflight (seated, supine), during spaceflight at rest and with the application of LBNP, and postflight (seated and supine). Box boundaries represent the 25th and 75th percentiles, with whiskers representing the 10th and 90th percentiles. Median and mean values are shown as solid and dotted lines within the boxes, respectively, with dots indicating outlying points. A linear mixed-effects model was used and found a main effect of measurement time point (P < 0.001). Tukey’s post hoc analysis results are indicated by the symbols as follows: *different from supine (P < 0.05); #different from seated (P < 0.05); and †value with LBNP application is significantly different from respective resting value (P < 0.05). The sample number and sex breakdown of each time point are as follows: pre-supine, n = 14, 3 females; FD45, n = 9, 2 females; FD45 + LBNP, n = 10, 2 females; FD150, n = 13, 2 females; FD150 + LBNP, n = 12, 2 females; R + 40-supine, n = 12, 2 females; R + 180-supine, n = 9, 1 female. FD45, 45th day of spaceflight; FD150, 150th day of spaceflight; LBNP, lower body negative pressure; R + 40, 40th day after returning to Earth from spaceflight; R + 180, 180th day after returning to Earth from spaceflight.