Falls in older people: effects of age and blurring vision on the dynamics of stepping.
OBJECTIVE
The risk of falling increases dramatically with age, and visual impairment is known to be an important risk factor. Therefore, it is highly pertinent to assess the effects of age and vision on the performance of everyday tasks linked to falling, such as stepping from one level to another.


METHODS
Nine young (age, 26 +/- 4 years) and ten elderly (age, 72 +/- 5 years) subjects performed a stepping-up task of three different heights. Their stepping strategies with blurred and optimally corrected vision were compared. Center of mass (CM), center of pressure (CP) dynamics (in the mediolateral and anteroposterior directions), and foot clearance parameters were determined, and statistical regression modeling was applied.


RESULTS
Elderly subjects spent 20% more time (P = 0.03) than young subjects during double support and they had reduced anteroposterior CM-CP divergence (P < 0.001) during double support and slower anteroposterior (P < 0.001) and mediolateral (P = 0.002) CM velocities during initiation of movement and single limb support. Blur caused similar adaptations, such as increased toe clearance, across both age groups, though mediolateral (ML) CM-CP divergence in elderly subjects was significantly more reduced than in young subjects (P < 0.001).


CONCLUSIONS
Findings indicate, in general, that older subjects used a more cautious and controlled stepping strategy. However, the lack of significant age differences in toe clearance suggests this strategy was mainly aimed at reducing ML instability rather than increasing margins of safety regarding toe clearance.
Heasley
Karen
K
Vision and Mobility Laboratory, Department of Optometry, University of Bradford, West Yorkshire, UK.
Buckley
John G
JG
Scally
Andy
A
Twigg
Pete
P
Elliott
David B
DB
D000058:Accidental Falls; D000222:Adaptation, Physiological; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D005260:Female; D005528:Foot / Q000502:physiology*; D005684:Gait / Q000502:physiology; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D014741:Video Recording; D014786:Vision Disorders / Q000503:physiopathology*