Age differences in postural sway during volitional head movement.
OBJECTIVE
To examine the role of a volitional self-paced head-turn movement on the postural sway characteristics of healthy young and elderly subjects.


METHODS
Cross-sectional design.


METHODS
Motor control research laboratory.


METHODS
Ten young adults and 10 elderly subjects.


METHODS
Postural sway characteristics of each subject were examined using a Kistler force platform. Each subject was tested under four experimental conditions: (1) static postural sway with vision; (2) static postural sway without vision; (3) postural sway with vision and self-paced head-turn movement; and (4) postural sway with no vision and a self-paced head-turn movement. Subjects performed six 15-second trials in each experimental condition. Dependent variables analyzed on each trial were mean sway amplitude (in millimeters), sagittal sway standard deviation, lateral sway standard deviation, and frequency of sway (in hertz).


RESULTS
During the static conditions (e.g., no voluntary movement), the young subjects produced significantly less postural sway than the elderly in both the vision condition (sway amplitude in the young, 3.80 mm; in the elderly, 4.89 mm) and the no-vision condition (young, 5.44 mm; elderly, 5.95 mm). This increased sway was the result of greater lateral sway in the elderly for the vision condition (3.73 vs. 2.68 mm), and greater sagittal sway for the elderly in the no-vision condition (5.55 vs. 4.70 mm). There were no significant differences between the groups in the frequency of sway. When asked to initiate and complete the head-turn, elderly subjects significantly increased their mean sway amplitude and decreased their frequency of sway, whereas the young subjects did not significantly alter their postural sway profiles.


CONCLUSIONS
These results demonstrate different postural sway control strategies for young and elderly subjects when asked to perform volitional movements.
Koceja
D M
DM
Department of Kinesiology and Program in Neural Science, Indiana University, Bloomington 47405, USA.
Allway
D
D
Earles
D R
DR
D000058:Accidental Falls; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D003430:Cross-Sectional Studies; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D004856:Postural Balance / Q000502:physiology; D011187:Posture / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology*