Unpredictability of fighter pilot G tolerance using anthropometric and physiologic variables.

Correlation and regression analyses were used to study relationships between centrifuge G tolerances of 1,434 fighter pilots during High-G Training (HGT) and anthropometric and physiologic variables. Multiple regression analyses yielded a four-variable model in which gradual onset run (GOR) relaxed-G tolerance was inversely correlated with height and directly correlated with age, weight, and diastolic blood pressure. Although the four-variable model was able to predict more of the variation in G tolerance than any single variable, neither method showed a correlation (r) of greater than 0.35 with GOR relaxed or straining G tolerance. No subject variable was significantly different between the pilot groups that did and did not experience G-induced loss of consciousness. We conclude that prediction of G tolerance during centrifuge HGT is unreliable using anthropometric and physiologic variables. The anti-G straining maneuver remains the major determinant of an individual's G tolerance.