Backgound:

Posturography is widely used to describe and analyze human postural control. The traditional features of the center of pressure (CoP) trajectory during open eyes quiet standing tests have been used to show the association between declined sensorimotor systems and the variation in fall-related concerns (FrC), but seem to be too crude to separate each sensorimotor system’s contribution. Therefore, research has moved towards analysing the frequency domain of the CoP trajectory.

Aim:

To explore the frequency domain of CoP trajectory signals in an effort to learn more about ageing postural control and how it mediates and is mediated by FrC 

Method:

We recruited 45 people aged 70 or more. To measure body sway during quiet stance, we registered CoP trajectories using a force plate. A power spectral density analysis was performed on the CoP signal of all participants, from which we then extracted features: peak power, mean power, 50% power and 80% power. Principal component analysis, orthogonal projection to latent structures (OPLS), and OPLS-discriminant analysis were used to explore patterns of explanation of the features by a wide range of sensorimotor variables and FrC measured on the participants. A PLS-tree was used for the initial grouping.

Results:

The PLS-tree gave 2 groups. Group 2 had significantly more FrC, lower morale, larger errors in knee proprioception, slower reaction times, and weaker lower limb strength. They also had lower frequencies at all four features (significant at all but peak power).

Conclusions:

Under the assumption that the vision feedback loop generates more power in the lower frequencies of quiet stance sway, one explanation of the findings could be that once an individual starts experiencing postural control decline, vision gets weighed heavier in the integration process. More research is needed to find the most accurate ways to investigate postural control changes.