Posturographic Balance's Validity in Mental and Physical Fatigue Assessment Among Cadet Pilots. 
BACKGROUND: Postural control is adversely affected by mental and physical fatigue, but its validity in fatigue assessment has not been investigated systemically among pilots.  We explored the correlations of posturographic balance with physiological and psychological signals among cadet pilots. METHODS: In experiment 1, 37 cadet pilots performed a posturographic balance test, heart rate variability (HRV), and profile of mood states (POMS) during 40 h of sleep deprivation.  For experiment 2, physiological signals of 60 subjects, including breathing rate (BR), systolic blood pressure (SBP), and heart rate (HR) were measured under the effects of physical fatigue.  Then correlations with a mental and physical fatigue index based on effective posturographic parameters with those subjective and objective methods were analyzed by linear regression. RESULTS: The mental fatigue index correlated linearly with the depression score of the POMS (r = 0.212), standard deviation of normal to normal beats (r = 0.286), and square root of the mean differences of successive beat intervals (r = 0.207).  Meanwhile, linear correlations with frequency-domain parameters of HRV such as total power, low frequency power, and high frequency power were also statistically significant.  With the increase in the physical fatigue index, physiological signals such as SBP (r = 0.300), HR (r = 0.349), and BR (r = 0.266) increased linearly. CONCLUSIONS: Impairment of postural stability can reflect the aggravation of mental and physical fatigue among cadet pilots, which provides a potential method for assessing fatigue level before flight tasks and preventing errors by pilots. Cheng S, Sun J, Ma J, Dang W, Tang M, Hui D, Zhang L, Hu W. Posturographic balance's validity in mental and physical fatigue assessment among cadet pilots.  Aerosp Med Hum Perform.  2018; 89(11):961-966.