Effectiveness of fingertip light contact in reducing postural sway in older people.
BACKGROUND AND OBJECTIVE: haptic cues from fingertip light touch (LT) with a stationary surface reduce postural sway even at non-mechanically supportive force levels. Aim of this study was to determine the effects of LT on postural sway in older compared with younger persons. SUBJECTS: twenty young (age 20-29, mean 23.9 + 2.5) and 20 older participants (age 65-83, mean 74.3 + 6.4). METHODS: subjects stood in the semi-tandem position on a firm surface, and their postural sway was quantified using a force platform. Experimental trials, randomised across subjects, included two sight conditions (vision and no vision) and three contact conditions (no touch, NT; light touch, LT; and force touch, FT). The measured parameters were the length and the area of centre of pressure sway (COP-L and COP-A) and the mean velocity of COP displacements in the anterior-posterior (COP-AP) and medial-lateral (COP-ML) direction. RESULTS: for all variables, the analysis showed significant differences between contact conditions, sight conditions and age. Contact-age interaction was significant between NT and LT conditions, with older participants showing greater decrease in postural sway than younger participants, but not between FT and LT conditions. CONCLUSIONS: results indicate that the effectiveness of LT in reducing postural sway may be greater in older than in younger persons, perhaps because in older persons haptic cues from upper extremity might counterbalance sub-clinical sensory loss in the lower extremities. This finding supports the hypothesis that older people may sometimes use a walking aid as an informative device and suggests that during balance training external aids should not be used.