Age-related changes in postural responses revealed by support-surface translations with a long acceleration-deceleration interval

Abstract

Objectives: The objectives were to examine (a) whether surface translations with a long, compared to a short, acceleration-deceleration interval could reveal more age-related differences in postural control and (b) whether age-related differences were associated with reactive or anticipatory postural mechanisms.

Methods: Ten older (66-81years) and ten young adults (22-39years) stood on a moveable platform that was unexpectedly translated in the backward direction. Subjects' electromyographic (EMG) and kinematic responses were recorded in response to translations with either a SHORT (100ms) or LONG (2s) acceleration-deceleration interval presented in either a predictable or random order.

Results: Age-related differences in kinematic postural responses were greater during LONG compared to SHORT translations. However, both LONG and SHORT translations elicited a similar change in EMG latencies and amplitudes between the older and young adults. No age effects on the presentation order (predictable or random) of the translations were observed.

Conclusions: LONG compared to SHORT surface translations magnify the age-related kinematic but not the EMG changes in reactive postural control. The anticipatory component of postural control was not affected by age.

Significance: Translations with longer acceleration-deceleration intervals reveal more age-related differences in postural control, which are otherwise masked by the deceleration effects inherent to shorter translations.