Flight-associated cortisol dynamics and subjective assessments of pain and stress in fighter pilots: an exploratory study

Abstract

Purpose: Operating a high-performance fifth-generation fighter jet is a potential stressor in which hypothalamic-pituitary-adrenal (HPA) axis dynamics may reflect the intensity of and adaptation to the stressor. The purpose of this study was to evaluate HPA axis activity in fighter pilots and explore whether indices of activity correlated with subjective indices of stress.

Methods: We studied HPA axis dynamics in 20 experienced fifth-generation fighter pilots (18 men/2 women) by measuring salivary cortisol at various times from bedtime the night before a flight training to awakening the morning after the flight training. We also measured plasma ACTH and serum cortisol the day before the flight and immediately following the flight. These findings were correlated with prior pilot flight experience and subjective assessments of pain and stress.

Results: Seven (35%) of the pilots demonstrated normal salivary cortisol levels at all time points despite one having a high index of pain. Lower pre-flight salivary cortisol was correlated with more flight hours in the year leading up to the flight exercise. Flight day awakening salivary cortisol was inversely correlated with pilot-reported post-flight stress. In general, there were no other major correlations suggesting a disconnect between an objective measure of stress via HPA axis dynamics and subjective indices of stress and pain.

Conclusion: The acute HPA axis response in some experienced fighter pilots habituates to the stressor of flying a fighter jet during a training exercise. The experience of the pilot was a determinant of their HPA axis stress response.

Keywords: ACTH; HPA axis; Military pilots; Salivary cortisol.