Fig. 4
From: Adaptation to microgravity, deconditioning, and countermeasures
Muscle sympathetic nerve activity plotted as a function of left ventricular stroke volume before and on landing day after 16 days of spaceflight (mean ± SE). With a change in position from supine to upright, stroke volume decreased, and sympathetic nerve activity increased. Stroke volume significantly decreased, and sympathetic nerve activity increased after spaceflight in both supine and upright positions. However, a relationship was maintained similar to that before spaceflight. *p < 0.05 for comparison between pre- and postflight muscle sympathetic nerve activity and stroke volumes (redrawn from data in Ref. [71])