PhD Scientific Days 2025

Poster Session I. - T: Cardiovascular Medicine and Research

Heart Rate Variability Reveals Complex Autonomic Responses to High Gravitational Loads in Aerobatic Flight

Name of the presenter

Nagy-Bozsoky József

Institute/workplace of the presenter

Semmelweis University, Department of Aviation and Space Medicine

Authors

Dr. József Nagy-Bozsoky¹, Dr. Klaudia Vivien Nagy¹, Alexandra Karsai¹

1: Semmelweis University, Department of Aviation and Space Medicine

Text of the abstract

Introduction: High gravitational loads experienced during flight impose significant stress on pilots' cardiovascular and autonomic nervous systems. Understanding acute cardiovascular responses to such acceleration is crucial for preventing G-induced physiological events, including syncope or loss of consciousness.

Aims: The aim of this study was to investigate autonomic cardiovascular regulation and sympathovagal balance during aerobatic flight with exposure to high gravitational loads (G-forces).

Methods: Four HUNOR astronaut candidates participated in a four-flight aerobatic G-acceleration demonstration and evaluation program (15-30 min/flight). Continuous 12-lead ECG and acceleration data were recorded. NN intervals were extracted, filtered, and analysed to compute time-varying HRV metrics. The following HRV indices were included: Mean NN, Standard Deviation of NN intervals (SDNN), and Root Mean Square of Successive Differences (RMSSD) as time-domain indices. Frequency-domain indices included normalized High Frequency (HFn), normalized Low Frequency (LFn), and LF/HF ratio. Cardiac Vagal Index (CVI) and modified Cardiac Sympathetic Index (CSI) were also calculated.
Pre-flight and in-flight averages were compared using Wilcoxon tests with Bonferroni correction.

Results: Mean NN interval remained statistically unchanged (675.2 [± 65.6] vs. 654.9 [± 102.1] ms, p=NS). SDNN (60.9 [± 21.0] vs. 97.1 [± 24.0] ms, p<0.001) and RMSSD (19.9 [± 7.6] vs 30.5 [± 9.2] ms, p<0.001) significantly increased. LFn (0.45 [± 0.13] vs 0.59 [± 0.16] n.u., p<0.001) and LF/HF ratio (7.7 [± 5.0] vs 11.0 [± 6.7], p=0.04) increased significantly, while HFn did not (0.09 [± 0.05] vs 0.07 [± 0.05] n.u., p=NS). CVI (4.22 [± 0.33] vs 4.64 [± 0.25], p<0.001) and mCSI (2249 [± 1411] vs 3576 [± 1501], p<0.001) showed significant increases.

Conclusion: Unlike mean heart rate, HRV indices sensitively revealed autonomic and cardiovascular responses to high-G flight. In addition to sympathetic activation, a notable increase in parasympathetic tone was observed, likely reflecting post-acceleration venous redistribution and anti-G breath holding maneuvers. These findings highlight the utility of advanced HRV metrics for assessing autonomic modulation under extreme physiological stress, such as high-G flight, where detailed assessment has previously been limited.