For eYcient prevention of falls among older adults, individuals at a high risk of falling need to be identiWed. In this study, we searched for muscle strength measures that best identiWed those individuals who would fall after a gait perturbation and those who recovered their balance. Seventeen healthy older adults performed a range of muscle strength tests. We measured maximum and rate of development of ankle plantar Xexion moment, knee extension moment and whole leg push-oV force, as well as maximum jump height and hand grip strength. Subsequently, their capacity to regain balance after tripping over an obstacle was determined experimentally. Seven of the participants were classiWed as fallers based on the tripping outcome. Maximum isometric push-oV force in a leg press apparatus was the best measure to identify the fallers, as cross-validation of a discriminant model with this variable resulted in the best classiWcation (86% sensitivity and 90% speciWcity). Jump height and hand grip strength were strongly correlated to leg press force (r = 0.82 and 0.59, respectively) and can also be used to identify fallers, although with slightly lower speciWcity. These results indicate that whole leg extension strength is associated with the ability to prevent a fall after a gait perturbation and might be used to identify the elderly at risk of falling.

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Daily-life accelerometry contributes substantially to the identification of individuals at risk of falls, and can predict falls in 6 months with good accuracy.

BackgroundFalls in frail elderly are a common problem with a rising incidence. Gait and postural instability are major risk factors for falling, particularly in geriatric patients. As walking requires attention, cognitive impairments are likely to contribute to an increased fall risk. An objective quantification of gait and balance ability is required to identify persons with a high tendency to fall. Recent studies have shown that stride variability is increased in elderly and under dual task condition and might be more sensitive to detect fall risk than walking speed. In the present study we complemented stride related measures with measures that quantify trunk movement patterns as indicators of dynamic balance ability during walking. The aim of the study was to quantify the effect of impaired cognition and dual tasking on gait variability and stability in geriatric patients.MethodsThirteen elderly with dementia (mean age: 82.6 ± 4.3 years) and thirteen without dementia (79.4 ± 5.55) recruited from a geriatric day clinic, walked at self-selected speed with and without performing a verbal dual task. The Mini Mental State Examination and the Seven Minute Screen were administered. Trunk accelerations were measured with an accelerometer. In addition to walking speed, mean, and variability of stride times, gait stability was quantified using stochastic dynamical measures, namely regularity (sample entropy, long range correlations) and local stability exponents of trunk accelerations.ResultsDual tasking significantly (p < 0.05) decreased walking speed, while stride time variability increased, and stability and regularity of lateral trunk accelerations decreased. Cognitively impaired elderly showed significantly (p < 0.05) more changes in gait variability than cognitive intact elderly. Differences in dynamic parameters between groups were more discerned under dual task conditions.ConclusionsThe observed trunk adaptations were a consistent instability factor. These results support the concept that changes in cognitive functions contribute to changes in the variability and stability of the gait pattern. Walking under dual task conditions and quantifying gait using dynamical parameters can improve detecting walking disorders and might help to identify those elderly who are able to adapt walking ability and those who are not and thus are at greater risk for falling.

Tripping over an obstacle can result in a fall when the forward angular momentum, obtained from impact with the obstacle, is not arrested. Angular momentum can be restrained by proper placement of the recovery limb, anteriorly of the body, but possibly also by a reaction in the contralateral support limb during push-off. The purpose of this study was to quantify the extent to which the support limb contributes to recovery after tripping by providing time and clearance for proper positioning of the recovery limb, and by restraining the angular momentum of the body during push-off. Twelve young adults were repeatedly tripped over an obstacle during mid-swing, while walking over a platform. Kinematics and ground reaction forces at the support limb were measured. Quantification of the angular momentum was based on calculation of the external moment, which equals the rate of change in the angular momentum of the body. Results showed that all subjects acquired a similar increase in angular momentum during foot-obstacle contact, on average 11.4 kg m2s(-1). In all subjects, the support limb played a role in recovery after tripping by providing time and clearance for proper positioning of the recovery limb, as indicated by body elevation (6%) and the increased forward pelvis displacement over recovery stride (43%). Almost all subjects were also able to restrain the forward angular momentum of the body during push-off by the support limb. Less angular momentum remained to be further accomplished by the recovery limb. Reductions in the quality of the support limb responses may be among the factors that increase the risk of falling in the elderly.