G-transition effects and their implications.

G-transition effects are defined as the spectrum of physiological and psychophysical effects induced by rapid changes in gravitoinertial forces, alternating between hypogravity (<1 Gz) and hypergravity (>1 Gz) and vice versa. They appear to involve the cardiovascular and spatial orientation systems. This note attempts to briefly review past and current research efforts on the consequences of G-transitions and to examine potential confounding Coriolis-induced bias in both ground-based and inflight research. A brief review of current evidence of vestibular influence on orthostatic compensation and their implications for G tolerance is presented. The effects of roll-induced hypogravity on subsequent G tolerance and possible misperception of attitude during roll rotation are discussed. An integrated approach is recommended for future research on acceleration and disorientation.