Supervisors info:
Μαρία Κοσκολού, Αναπληρώτρια Καθηγήτρια, Τμήμα Επιστήμης Φυσικής Αγωγής και Αθλτισμού, ΕΚΠΑ
Νίκος Γελαδάς, Καθηγητής, Τμήμα Επιστήμης Φυσικής Αγωγής και Αθλτισμού, ΕΚΠΑ
Γρηγόρης Μπογδάνης, Καθηγητής, Τμήμα Επιστήμης Φυσικής Αγωγής και Αθλτισμού, ΕΚΠΑ
Summary:
Maintaining a satisfactory fitness level is a necessary component for the pilots, that makes them effective and, consequently, ensures flight safety. Their ability to act effectively could be reflected on the time of useful consciousness (TUC), which corresponds to the period between the reduction of oxygen partial pressure of the inspiring air mixture and the moment at which an individual’s performance is significantly affected. Physical fitness and the oxygen carrying capacity of hemoglobin are included among the factors affecting TUC and reaction time (RT). To date, research results regarding the importance of aerobic capacity, by means of maximal oxygen uptake (VO2max), for cognitive responses in hypoxia remain controversial. Additionally, it remains unclear whether there are relationships among pilots’ responses (cognitive and physiological) in hypoxia and a) maximal voluntary contraction (MVC), b) percentage body fat (%BF) and c) hemoglobin mass (Hbmass), which are factors of regular cardiovascular function and aerobic capacity.
The aim of the present study was to investigate potential relationships among components of physical fitness (cardiovascular, muscular, metabolic and hematologic) and physiological (heart rate and percentage of hemoglobin saturation with oxygen) as well as cognitive responses (TUC and RT) of pilots during acute exposure to hypoxia. For this reason, 21 participants completed two experimental procedures. The first one included measurements of Hbmass, VO2max, MVC and body composition (%BF and body mass index, BMI). The second one assessed the pilots’ responses to hypoxia by acutely exposing them to hypobaric hypoxia of 25.000 ft (7620 m) during a flight simulation, where TUC and RT [to a single stimulus (MSRT) and multiple (MCRT) stimuli] were measured along with heart rate (HR) and the percentage of hemoglobin saturation with oxygen (SpO2).
VO2max, expressed in relative values (ml/kg/min), showed a significant positive correlation with TUC [r(21) = .37, p < .05] and a significant negative correlation with MCRT [r(21) = -.45, p < .05]. Furthermore, MCRT was positively correlated with BMI [r(21) = .62, p < .01] as well as with the rate of SpO2 decrease [r(21) = .81, p < .01]. MSRT was also positively correlated with rate of SpO2 decrease [r(21) = .38, p < .05]. Moreover, there was a negative correlation between Hbmass, expressed per unit of kg of lean body mass, and mean HR during the CRT test [r(21) = -.43, p < .05], as well as with the peak HR value attained during hypoxia exposure [r(21) = -.38, p < .05]. Lastly, mean HR during the CRT test was negatively correlated with TUC [r(21) = - .40, p < .05].
In conclusion, it appears that high aerobic capacity relates to high TUC and short MCRT, while MVC and body fat percentage are not related to cognitive and physiological responses of pilots during a flight simulation at 25.000 ft (7.620 m) altitude. Furthermore, it appears that high Hbmass values are negatively correlated with HR during hypoxia, such that individuals with higher Hbmass values showed lower HR values at the particular altitude simulation used in this study.
Keywords:
hypoxia, air force pilots, physical fitness, hemoglobin mass, time of useful consciousness, reaction time
