Does aging with a cortical lesion increase fall-risk: Examining effect of age versus stroke on intensity modulation of reactive balance responses from slip-like perturbations

We examined whether aging with and without a cerebral lesion such as stroke affects modulation of reactive balance response for recovery from increasing intensity of sudden slip-like stance perturbations. Ten young adults, older age-match adults and older chronic stroke survivors were exposed to three different levels of slip-like perturbations, level 1 (7.75m/s2), Level II (12.00m/s2) and level III (16.75m/s2) in stance. The center of mass (COM) state stability was computed as the shortest distance of the instantaneous COM position and velocity relative to base of support (BOS) from a theoretical threshold for backward loss of balance (BLOB). The COM position ( X COM / BOS ) and velocity ( X ̇ COM / BOS ) relative to BOS at compensatory step touchdown, compensatory step length and trunk angle at touchdown were also recorded. At liftoff, stability reduced with increasing perturbation intensity across all groups (main effect of intensity p <0.05). At touchdown, while the young group showed a linear improvement in stability with increasing perturbation intensity, such a trend was absent in other groups (intensity×group interaction, p <0.05). Between-group differences in stability at touchdown were thus observed at levels II and III. Further, greater stability at touchdown positively correlated with anterior X COM / BOS however not with X ̇ COM / BOS . Young adults maintained anterior X COM / BOS by increasing compensatory step length a...
Source: Neuroscience - Category: Neuroscience Source Type: research