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


CONCLUSIONS
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.
Tokuno
Craig D
CD
Department of Physical Education and Kinesiology, Brock University, St. Catharines, Ont., Canada L2S 3A1. ctokuno@brocku.ca
Cresswell
Andrew G
AG
Thorstensson
Alf
A
Carpenter
Mark G
MG
D000054:Acceleration; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D003654:Deceleration; D004576:Electromyography; D005260:Female; D006801:Humans; D007698:Kinesis / Q000502:physiology; D008297:Male; D009038:Motion; D018482:Muscle, Skeletal / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D011930:Reaction Time; D013997:Time Factors