Subjective stability perception is related to postural anxiety in older subjects

Under static conditions, the objective and subjective measures of postural stability correlate well. However, age-related changes in postural control and task-related anxiety may modify the relationship between these subjective and objective measures. Ultimately, patients' symptoms represent subjective reports, thus understanding this relationship has clinical implications.

This study investigates the relationship between subjective-objective measures of postural stability in dynamic conditions and whether this relationship is influenced by age or task-related anxiety.

50 healthy participants (aged 18-83 years) stood on a platform oscillating at variable amplitudes, with-without a fall-preventing harness to modulate task-related anxiety. Trunk sway path, hip velocity and foot lifts (objective measures) and subjective scores of instability and task-related anxiety were recorded.

The subjective perception of stability accurately matched objective body sway, following a logarithmic function profile (r² = 0.72, p < 0.001). This function did not change significantly with age, harness or task presentation order. A strong relationship was observed between subjective measures of stability and task-related anxiety for all subjects (r = 0.81, p < 0.001). Task repetition reduced anxiety in the young, uncoupling anxiety changes from subjective instability, but not in the elderly who retained higher anxiety levels in line with subjective unsteadiness.

Subjects accurately rate their own instability during dynamic postural challenges, irrespective of age and actual fall risk. However, anxiety may selectively modulate the perception of instability in older subjects. The perception of stability relies upon the integration of sensory afferents but also recruits emotional-cognitive processes, particularly in older individuals. The use of a safety harness has no influence on subjective or objective postural stability.