The postural control can be optimized by the first movement initiation condition encountered when submitted to muscle fatigue

Assessment of the static upright balance index and brain blood oxygen levels as parameters to evaluate pilot workload

Objective

To investigate the potential for static upright balance function and brain-blood oxygen parameters to evaluate pilot workload.

Methods

Phase 1: The NASA Task Load Index (NASA-TLX) was used to compare the workloads of real flights with flight simulator simulated flight tasks in 15 pilots (Cohort 1). Phase 2: To determine the effects of workload, 50 cadets were divided equally into simulated flight task load (experimental) and control groups (Cohort 2). The experimental group underwent 2 h of simulated flight tasks, while the control group rested for 2 h. Their static upright balance function was evaluated using balance index-1 (BI-1), before and after the tasks, with balance system posturography equipment and cerebral blood oxygen parameters monitored with near infrared spectroscopy (NIRS) in real time. Sternberg dual-task and reaction time tests were performed in the experimental and control groups before and after the simulated flight tasks.

Results

(Phase1) There was a significant correlation between the workload caused by real flight and simulated flight tasks (P<0.01), indicating that NASA-TLX scales were also a tool for measuring workloads of the stimulated flight tasks. (Phase 2) For the simulated flight task experiments, the NASA-TLX total scores were significantly different between the two groups (P<0.001) and (pre-to-post) changes of the BI-1 index were greater in the experimental group than in controls (P<0.001). The cerebral blood oxygen saturation levels (rsO₂) (P<0.01) and ΔHb reductions (P<0.05) were significantly higher in the experimental, compared to the control group, during the simulated flight task. In contrast to the control group the error rates (P = 0.002) and accuracy (P<0.001) changed significantly in the experimental group after the simulated flight tasks.

Conclusions

The simulated flight task model could simulate the real flight task load and static balance and NIRS were useful for evaluating pilots’ workload/fatigue.