Kang S, Hwang S, Lee ET, Yang S, Park J. Measuring the cumulative effect of G force on aviator neck pain. Aviat Space Environ Med 2011; 82:1042–8.Introduction: In many studies, high G force is thought to be the most important causal factor of aviator neck pain. However, most of the studies performed to date have compared neck pain of aviators exposed to high G force with that of aviators not so exposed or with that of the general population. As a result, neck pain for aviators exposed to high G force as it relates to G level is not yet well-known. Methods: The subjects were 1003 male aviators who were sent an anonymous questionnaire. Subject variables were information on physical characteristics, lifestyle, and flight characteristics, including information about exposed maximum G (G_max). There were three dependent variables: whether the aviator had experienced neck pain, frequency of neck pain, and subjective severity of neck pain. Result: With the multivariate analysis, amount of G_max exposure (frequency or monthly duration of G_max exposure) had a statistically significant positive relationship with all three dependent variable. BMI, flight hours in current aircraft, and posterior seat type had a meaningful positive relationship with experience of neck pain and subjective severity of neck pain. Other characteristics, including G_max level, were not significantly related with any dependent variables. Discussion: These results suggest that G level could have a ceiling effect; in other words, above a certain G level, aviator neck pain risk does not increase. This means that amount of G_max exposure becomes more influential on aviator neck pain than the level of G_max.