Assessment of the Maximum Ability to Maintain an Upright Position on an Unstable Support

Testing the maximum ability to maintain the balance of an upright body is in demand both in the physiology of posture regulation and, especially, in the diagnosis of athletic abilities. However, there is currently no technology for estimating maximum balance ability (MBA). The aim of the work was to develop and approbate a test for assessing MBA using eleven see-saws of decreasing radius of curvature movable in the sagittal plane in athletes of both sexes. Additional tasks were: 1) to compare the discriminating ability of the monopedal and bipedal test for MBA, 2) to evaluate the relationship of the MBA indicator with the area of fluctuations of the common center of pressure (ELS), determined on a stabiloplatform and simple see-saws, 3) to identify gender differences in MBA. To evaluate the MBA, a test has been developed with a stepwise increase in the difficulty of maintaining postural balance by the gradual reducing the curvature radius of see-saws. The MBA corresponded to the minimum radius of curvature of the see-saw, on which the subject could maintain balance for 15 seconds. In all the tasks of the test, the ellipse area of the center of pressure oscillations (ELS) was determined using a stabiloplatform (Stabilan 01-2). The application of the developed test on a sample of athletes (n = 78) showed that the discrimination index of the monopedal test was excellent (DI = 0.82) and significantly higher than the bipedal test (DI = 0.052). The MBA indicator in the bipedal test did not correlate with ELS in simple standing conditions, however, such weak and moderate correlations (r = -(0.27–0.48)) were established in the monopedal test. This indicates a weak predictive power of the stabilographic indicators defined in the usual stances. In both tests, the MBA indicator positively correlated with the maximum ellipse area of the center of pressure oscillations (ELSmax), showing the informative value of this indicator. The girls did not differ from the boys in MBA, but showed reduced ELS in stances on simple see-saws. To assess the maximum ability to balance, as well as the postural stability in submaximal conditions, a monopedal test with stepwise increasing complexity on movable see-saws can be used. Stablographic indicators obtained during usual quiet stances poorly predict MBA. The following indicators are the most informative about the MBA: the minimum radius of curvature of the see-saw and ELSmax, achieved in extremely difficult balance conditions. Gender differences do not affect MBA, but the postural stability on simple see-saws is higher for girls than for boys.

maximum balance ability, static monopedal balance, stabilography, see-saw, athletes