Monitoring military pilots with textile sensors: physiological responses and signal quality under extreme conditions.

Introduction: Military pilots are exposed to severe physiological challenges during their missions that may affect cognitive and physical performance. Therefore, continuous monitoring potentially provides critical insights about the impact of extreme condition exposure on the fitness to fly of military pilots. Methods: We applied a textile-based monitoring system during training sessions with pilot aspirants to investigate the impact of hypobaric hypoxia and high G-force exposures on the signal quality obtained for a 1-lead electrocardiogram (ECG) and chest excursions. The physiological variables considered were heart rate, heart rate variability, as well as respiratory frequency and respiratory amplitude. Results: In general, 93.4% and 90.4% of the recorded ECG time segments during hypoxia and G-force exposure, respectively, were classified as plausible for further analysis. For respiratory data, 70.7% and 81.3% were classified as accurate for further data analysis and interpretation. Discussion: Detailed information about signal quality was found to be critical for assessing physiological variables recorded in extreme conditions, including distinguishing between intra- and interpersonal variability. Furthermore, the combination of various physiological signals allows for a more holistic interpretation of body responses, for the assessment of body tolerances and an early detection of possible physical and cognitive impairments.