Estimation of Redox Status in Military Pilots during Hypoxic Flight-Simulation Conditions—A Pilot Study

Abstract

At high altitude conditions, the low-pressure atmospheric oxygen reduces the generation of energy, thus inducing a decrease in oxygen availability. As a result, endurance flights evoke imbalance in redox signaling, posing a safety risk for the pilots involved. The aim of the present study was to assess changes in the redox status of military pilots during flight simulation conditions according to their flight hours (experts vs. novice). A total of seven expert pilots and an equal number of novice pilots (trainees) were recruited from the Center for Airforce Medicine of the Greek Military Airforce. Glutathione (GSH) levels, catalase activity (CAT), total antioxidant capacity (TAC), lipid peroxidation through the thiobarbituric acid-reactive substances (TBARS), and protein oxidative damage through the assay of protein carbonyls (PCs) levels were assessed at two time points, once prior to and once immediately post a scheduled flight simulation. In the experienced pilots’ arms, GSH was significantly increased post-flight simulation, with TAC being simultaneously reduced. On the other hand, in the trainees’ arms, CAT and TAC were both increased post-flight. No differences were noted with regard to the TBARS and PCs post-simulation. When the two groups were compared, TAC and PCs were significantly lower in the trainees compared to the experienced pilots. The present study provides useful insight into the physiological redox status adaptations to hypobaric hypoxic flight conditions among pilots. In a further detail, an increase in GSH response post-flight simulation is being evoked in more experienced pilots, indicating an adaptation to the extreme flight conditions, as they battle oxidative stress.

Oxidative Stress Reaction to Hypobaric–Hyperoxic Civilian Flight Conditions

“…Our results confirm, in some way, the outcomes of former studies concerning military flight operations from members of our work group [7], who showed that flight operators with higher inflammatory biomarkers have a higher tendency to develop signs of chronic fatigue, but that these higher levels of inflammatory biomarkers cannot be, or are only in part, causally related to the number of performed flights and level of hypobaric hyperoxia. In fighter pilots in hypobaric hypoxic conditions, it seems that glutathione and three other oxidative stress markers increased with a higher tendency of oxidative stress elevation in experienced fighter pilots with more flight hours [25]. This could lead to two assumptions.…”

Endogenous Risk Factors of Cardiovascular Diseases (CVDs) in Military Professionals with a Special Emphasis on Military Pilots

“…Petraki et al assessed the effects of a flight simulation on the antioxidative status (total antioxidant capacity—TAC, CAT, and GSH) as well as the oxidative modifications of proteins and lipids through the measurement of protein carbonyls (PCs) and thiobarbituric acid reactive species (TBARS) of military pilots with differing flying experiences. They observed an adaptation to the flight training in an effort to battle oxidative stress in experienced pilots, revealed by increased levels of GSH [ 58 ]. Corsi et al proposed erythrocyte glycohydrolases as new sensitive markers to assess oxidative stress, and they investigated their concentration in air force pilots.…”