Perceived workload and heart rate variability in elite military pilots recovering from operational maintenance and air demonstration flights

Introduction Military pilots are exposed to high psychophysiological demands arising from Q9 environmental, operational, and cognitive factors. Heart rate variability (HRV) has been widely used as a non-invasive marker of autonomic modulation, whereas the NASA Task Load Index (NASA-TLX) allows the assessment of perceived workload. However, few studies have simultaneously investigated these parameters in aerial demonstration pilots. Objective To compare autonomic responses assessed by HRV and perceived workload in pilots from the Brazilian Air Force Aerial Demonstration Squadron during recovery following operational maintenance (OM) and aerial demonstration (AD) flights. Methods Nine elite military pilots (32 ± 3 years) performed two flights with an average duration of 50 minutes: an OM flight, characterized by lower operational complexity, and an AD flight, characterized by higher operational complexity and involving seven aircraft performing synchronized aerobatic maneuvers. HRV was recorded using the Equivital® system and analyzed with Kubios® software, including SDNN, RMSSD, LF, HF, and LF/HF during an immediate post-flight recovery segment. After each flight, perceived workload was assessed using the NASA-TLX. Comparisons between conditions were performed using the Wilcoxon signed-rank test, with statistical significance set at p < 0.05. Results AD flights showed higher scores for temporal demand (+29%; p = 0.01) and effort (+28%; p = 0.03), as well as percentage increases in the other NASA-TLX dimensions. Most HRV indices remained stable between conditions (p > 0.05). The only significant difference was observed for maximum heart rate, which was 9% lower in the post-flight comparison between OM and AD conditions (p = 0.01). Discussion Exploratory correlation analyses revealed sparse and largely non-significant associations between HRV indices and NASA-TLX dimensions, with only a few nominal associations involving temporal demand and the spectral HF component. Conclusion Aerial demonstration flights were associated with higher perceived workload scores, particularly in the temporal demand and effort dimensions. However, no statistically significant differences were detected for most HRV indices assessed during the immediate post-flight recovery period. These findings suggest relative stability of autonomic responses in highly experienced military pilots, even in the presence of increased perceived workload.