An overview of age-related changes in postural control during quiet standing tasks using classical and modern stabilometric descriptors.

Age-related changes in postural control during quiet standing likely result from underlying pathological conditions or from the low specificity of classical stabilometric parameters, which are vulnerable to base of support configurations and anthropometric differences. This study focuses on the identification of changes in postural control with natural aging by using conventional and recent stabilometric analysis, and on the interpretation of the stabilometric parameters according to a recently proposed framework of postural control. Quiet standing stabilometric tests were applied to 57 subjects equally divided into young, middle-aged and aged groups (19-29, 38-51 and 65-73 years, respectively) with eyes open and closed conditions. In addition to estimation of classical descriptors, center of pressure time series were approached according to a diffusion-like process and the recently proposed sway density curve. Two out of 10 estimated descriptors identified between-group differences. Aged subjects exhibited higher sway frequencies, possibly resulting from the increase of torque bursts produced by the plantar flexors, and stronger negative correlation between consecutive center of pressure displacements observed for long time intervals, likely due to higher amplitude of plantar flexors torque. Aging itself does not result in major changes of postural stability, but reflects a small increase in plantar flexion torque amplitude and frequency of torque adjustments, probably to compensate for the lower stiffness of calf muscle tendon in aged subjects.