Search results for "Base of support"
showing 4 items of 4 documents
Reactive Response and Adaptive Modifications in Dynamic Stability to Changes in Lower Limb Dynamics in the Elderly while Walking
2011
The aim of this study was to examine the reactive responses and adaptive modifications in dynamic stability resulting from a unilateral change in lower limb dynamics in older and younger adults while walking. Eleven older (62- 76yrs) and eleven younger (22-30yrs) subjects walked on a treadmill and performed different gait conditions using an external resistance against lower limb movement. The margin of stability (MoS) at touchdown was calculated as the difference between base of support (BoS) and extrapolated centre of mass. After the resistance was turned on unexpectedly, older adults needed more steps to get back to the MoS baseline level due to a lower increase of the BoS. In the follow…
Mechanisms of Adaptation from a Multiple to a Single Step Recovery Strategy following Repeated Exposure to Forward Loss of Balance in Older Adults
2012
When released from an initial, static, forward lean angle and instructed to recover with a single step, some older adults are able to meet the task requirements, whereas others either stumble or fall. The purpose of the present study was to use the concept of margin of stability (MoS) to investigate balance recovery responses in the anterior-posterior direction exhibited by older single steppers, multiple steppers and those that are able to adapt from multiple to single steps following exposure to repeated forward loss of balance. One hundred and fifty-one healthy, community dwelling, older adults, aged 65-80 years, participated in the study. Participants performed four trials of the balanc…
Is backward disequilibrium in the elderly caused by an abnormal perception of verticality? A pilot study
2007
International audience; OBJECTIVE: We hypothesised that backward disequilibrium (BD), defined by a posterior position of the centre of mass with respect to the base of support, could be caused by a backward tilt in the perception of verticality. METHODS: The relationship between BD, the perception of verticality, and the history of falls in 25 subjects aged 84.5+/-7.4 years was analysed. An original ordinal scale, the BD scale (BDS), was used to quantify BD. Postural (PV) and haptic verticals (HV) were measured in sagittal plane. RESULTS: BDS scores closely correlated with the number of falls (r = 0.81, p =10(-5)). The more the PV was tilted backward, the greater the BDS scores (r = -0.95, …
Standing up from a chair as a dynamic equilibrium task: a comparison between young and elderly subjects.
2000
The purpose of this study was to analyze and compare the features of center of mass (CoM) control along anterior/posterior axis in young and elderly subjects during sit-to-stand (STS). From a sitting position, seven healthy young subjects and seven healthy elderly subjects were asked to stand up from a chair under different experimental conditions (visual conditions: normal and blindfolded; speed: normal and as fast as possible). Analysis of results was based upon the concept of a “dynamic equilibrium area” (DEA), which in turn identified the dynamic limits of balance. The results showed that both the maximal CoM velocity in the horizontal axis and the CoM velocity at the instant of seat-of…