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Background: One of the more pervasive effects of aging is loss of cutaneous sensation, which appears to correlate with impaired postural control and increased risk of falling. This study examined the potential for compensating for the destabilizing effects of reduced cutaneous sensitivity by placing a raised edge underneath the perimeter of the plantar foot surface, so as to facilitate sensation from the stability boundaries of the base of support.Methods: The main experiment involved 14 healthy older adults (aged 65-73) selected because they were known, from a previous study, to have moderate plantar cutaneous insensitivity. We also report results of an initial experiment involving 7 healthy young adults (aged 23-31). In both experiments, we studied effects of the plantar facilitation on control of rapid stepping reactions evoked by unpredictable postural perturbation, applied via sudden platform movement in forward, backward, and lateral directions. We also studied effects on "feet-in-place" responses evoked by continuous pseudorandom platform motion in mediolateral and anteroposterior directions. Subjects were blindfolded in all tests.Results: Plantar facilitation reduced the incidence of "extra" limb movements, beyond the initial step, during forward-step reactions in the older adults. There also appeared to be an improved ability to control feet-in-place reactions: young subjects were better able to recover balance without stepping when falling backward (given instructions to "try not to step"), and both young and older subjects reduced the extent to which the center of foot pressure approached the posterior foot boundary during continuous anteroposterior platform motion.Conclusions: This study provides evidence that mechanical facilitation of sensation from the boundaries of the plantar surface of the foot can improve the efficacy of certain types of stabilizing reactions evoked by unpredictable postural perturbation. The results may be directly transferable to the design of special footwear insoles to reduce instability and risk of falling in older adults. [ABSTRACT FROM AUTHOR]

The paper outlines a biomechanical approach to quantifying anticipatory postural adjustments in the elderly. The measurement problems that occur in applying the biomechanical approach to elderly subjects are described and the 'signal-to-noise' properties of three candidate measures are compared, using data from volitional unilateral arm-raise tests performed on 100 elderly subjects. The results suggest that changes in vertical ground reaction force provide the greatest potential for accurate measurement of anticipatory adjustments, in comparison with changes in horizontal force or centre-of-pressure displacement. By normalising the anticipatory change in vertical ground reaction force with respect to the vertical perturbation force induced by the arm motion, a measure of relative anticipatory response is derived. The use of this measure, as well as its limitations, are demonstrated by analysing its relationship to actual falling risk, monitored prospectively in the elderly subject population. The findings showed evidence of larger relative anticipatory adjustments in the subjects who experienced recurrent falls, and it is suggested that these responses may be indicative of disordered motor programming. However, to detect these differences, it was necessary to average responses over multiple trials and to exclude trials with very small arm acceleration or very large baseline 'noise' (associated with ongoing postural sway). The need to screen and exclude data would seem to limit the practical utility of this approach in testing elderly populations. [ABSTRACT FROM AUTHOR]

Background: This study compares several psychological indicators of balance confidence in relation to physical performance, past and current experience, gender bias, and other perceptions of daily functioning.Methods: Sixty community-dwelling ambulatory elders (aged 65-95) were administered the Falls Efficacy Scale (FES), the Activities-Specific Balance Confidence Scale (ABC), and three dichotomous questions on fear of falling, activity avoidance, and perceived need for personal assistance to ambulate outdoors. Performance measures on walking (average speed) and balance (static posturography) were obtained on a subsample of 21 subjects.Results: Balance confidence assessed by the ABC and self-perceived need for personal assistance with outdoor ambulation were the only indicators significantly associated with the performance measures. As expected, perceived balance capabilities were more strongly related to current behavior (frequency of doing specific activities) than to past experience (fall history). Gender differences in self-report emerged for the global fear-of-falling indicator but not for the two efficacy ratings.Conclusions: Psychological indicators of balance confidence are important to measure both in conjunction with balance test performance and as a legitimate focus of rehabilitation. Of the various indicators assessed here, the dichotomous fear-of-falling question appears to have the least utility. Perceived need for personal assistance to ambulate outdoors has merit as an initial clinical screening question for discriminating persons on the basis of both physical ability and confidence. The ABC scale appears to have the greatest utility as an evaluative index for older persons at a moderate to high level of functioning. [ABSTRACT FROM AUTHOR]