Heart rate variability in student pilots during the flight training: a preliminary report

Abstract

Heart rate (HR) indicates the number of beats per minute (bpm) of the heart, while heart rate variability (HRV) indicates the temporal fluctuation of the intervals between adjacent beats (NN). HRV expresses neuro-cardiac activity and is generated by heart-brain interactions and dynamics related to the function of the Autonomous Nervous System (ANS) and other components (body and ambient temperature, respiration, hormones, blood pressure). The flight activity, especially during training, provides for a prolonged state of alert of the student pilot, as well as careful management of the flight and simultaneous planning of the next steps, with attention to the unusual conditions and emergencies that may occur during all various stages. HRV can provide a good reference index for estimating the degree of evolution of the training process of student pilots and a valid tool for some indications of a physiological as well as clinical nature. To investigate this issue, we started a series of experiments, still ongoing, by coupling the flight task times of student pilots with changes in their HRV. Before each experimental session, the participating pilot student was equipped with five electrodes, three-channel Holter (ECG BIOMEDICAL, BI9100). For this purpose, we have defined three-time phases: ground flight operations (bfo), in-flight operations (dfo) and post-flight ground operations (afo). The HRV analysis was carried out using the time domain and frequency domain parameters. As regards the mean of the RR intervals in the dfo, an increase was observed in 29% of the sample, while a decrease was observed in the remaining 71%, compared to that in the bfo. The analysis of the data relating to very low frequencies (VLF), low frequencies (LF) and high frequencies (HF) in the sample highlighted the values indicated below. In dfo, an increase in VLF values in 18% of the sample and a decrease in 82% in the remaining 71% compared to what was observed in bfo. LF values in dfo increased in 29% of the sample and decreased in the remaining 71%, compared to bfo. Finally, the HF, in dfo increased in 29% and decreased in 71% of cases, compared to the values of the bfo. Additional significant differences were found between the cases in which the RR intervals decreased in the dfo compared to the bfo, and those in which the RR intervals increased in the dfo compared to the bfo. In conclusion, the observed data lead to reconsider some physiological correlates of the different components involved in the determinism of HRV of a subject who carries out intense psychophysical activity for a certain period. In fact, it is necessary to evaluate the role of the ANS, in its various divisions (parasympathetic, sympathetic, and enteric), as well as the activity of the baroreceptors, the respiratory cycle (respiratory sinus arrhythmia), the thermoregulatory and hormonal factors within the short and medium tasks term.