Defining Normal Balance for US Army Aviators

Research Paper Title

Defining Normal Balance for Army Aviators.


One challenge clinicians face is determining when a military Service Member (SM) can return to duty after an injury that affects the postural control.

The gold standard to measure postural control is the Sensory Organisation Test (SOT). This test measures the amount of sway present in an individual’s static stance that may be used to examine range of function and monitor recovery from injury.

Normative values currently available were developed using a sample of clinically normal adults from the general population (i.e., civilian non-aviator). Previous research suggests that these values should not be used as a comparative cohort for high-performing populations in the military.

However, normative values, specific to military SMs, do not exist. The aim of this study was to develop a normative clinical database for functional balance (i.e., the SOT) for military-trained aviators, an occupational specialty that may consist of high performers.


Forty-three U.S. Army trained aviators, between 23 and 40 years old with medical clearance for flight operations from the Fort Rucker, Alabama area community consented and participated in this study. The SOT was delivered using the NeuroCom SMART EquiTest Clinical Research System with the Data Acquisition Toolkit (version 9.3).


A statistically significant (p < 0.01) difference between the study cohort of Army-trained aviators and the publically available general civilian normative values was found for the more challenging conditions, in which the force plate was not fixed (i.e., conditions four through six). The study cohort of Army-trained aviators were found to have a higher equilibrium score in each of these three conditions.

Similarly, a significant difference (p < 0.01) between the two cohorts was found on the visual and vestibular sensory analysis ratios, and the visual preference scores (i.e., greater reliance upon visual information in the maintenance of balance). The study cohort were found to have a higher ratios (i.e., greater dependence upon these sensory cues) in each of these conditions.


Army-trained aviators are high-functioning performers whose SOT scores differ from that of the general civilian population, particularly for the more challenging test conditions. New normative values were developed from this study population. Use of the developed normative values could be used as a comparative cohort in screening aviators who are recovering from injuries that affect postural stability.


Karch, S.J., Lawson, B.D. & Milam, L.S.. (2019) Defining Normal Balance for Army Aviators. Military Medicine. 184(7-8), pp.e296-e300. doi: 10.1093/milmed/usz064.


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