Stepping characteristics and Centre of Mass control during stair descent: Effects of age, fall risk and visual factors.

Stair edges provide important visual cues for appropriate foot placement on the stair and balance control during stair descent. Previous studies explored age-related changes in stepping performance and balance control during stair descent and included fit older adults. The present study investigates both age- and frailty-related changes to stepping parameters and Centre of Mass (COM) control during stair descent and how these measures are affected by visual factors. Older adults were split into two groups containing participants with the lowest (LROA, n=7) and highest (HROA, n=8) combined scores on tests of balance and confidence to negotiate stairs. Data were also collected from younger adult participants (YA, n=8). Kinematic data were collected from participants while they descended stairs under combinations of ambient light (bright and dimmed) and stair edge contrast conditions (high and low). A three (group) × two (illumination)×two (contrast) ANCOVA was performed with average stair walking speed as covariate. HROA cleared the stair edge vertically (p=0.001) and horizontally (p<0.001) with less distance than LROA. Dimmed ambient light resulted in decreased step length in HROA (p=0.006) compared to bright lighting. High stair edge contrast led to reduced vertical COM acceleration variability in HROA (p=0.009) and increased distance between COM and anterior base of support (p=0.017) in LROA. YA increased horizontal foot clearance (p=0.011) when stair edge contrast was high. We conclude that the aforementioned differences in stepping behaviour shown by HROA may contribute towards an increased risk of tripping and that high stair edge contrast has a beneficial effect on balance control in older adults.

Stroke-related differences in axial body segment coordination during preplanned and reactive changes in walking direction.

This study quantitatively describes differences between participants with hemiparetic stroke and age-matched healthy participants in axial body segment and gait kinematics during a direction change task. Participants were required to change walking direction by 45 degrees, either to their left or right, at the midpoint of a 6-m path. Participants were visually cued either at the start of the walk (pre-planned) or one stride before they reached the turn point (reactive). The sequence and inter-segmental timing of axial orientation onset was preserved in participants with stroke. Analysis of a subgroup of stroke survivors indicated that participants with lesions affecting the basal ganglia (BG) took significantly longer time than control participants to initiate the reorientation synergy when making turns to their non-paretic side. We hypothesize that these differences are a product of asymmetrical activity of dopaminergic pathways in the brain resulting from compromised BG function.

Kinematics of turning 180 degrees during the timed up and go in stroke survivors with and without falls history.

BACKGROUND: Community-dwelling, chronic stroke survivors are at risk of falling during turning and are more likely to sustain a hip fracture when they fall. OBJECTIVE: This study quantifies kinematic differences between stroke survivors (mean +/- SD: 38.3 +/- 31.3 months post-stroke, 59.9 +/- 10.1 years of age), with (n = 9) and without a falls history (n = 9), and age-matched healthy counterparts (n = 18) in turning coordination during the 180 degrees turn around in the Timed "Up & Go" (TUG) test. METHODS: Full-body kinematics were recorded while participants performed the 180 degrees turn around in the TUG. Dependent measures were time to turn, number of steps to turn, and measures of axial segment coordination. Result. Although participants who had a stroke and falls history took significantly longer to turn (mean +/- SD: 4.4 +/- 1.7 seconds) than age-matched controls (2.5 +/- 0.6 seconds), no kinematic differences were found in performance or in the axial segment coordination during turning that could contribute to falls history or falls risk. CONCLUSIONS: These results indicate incidences of falls during turning following stroke may not be due to impaired movement patterns but due to the many other factors that are associated with falls, such as deficits in cognitive processes--attention or central integration--and/or sensory deficits.

Seated bilateral leg exercise effects on hemiparetic lower extremity function in chronic stroke.

BACKGROUND: Bilateral arm training with rhythmic auditory cueing (BATRAC) improves hemiparetic upper extremity (UE) function in stroke. It is unknown whether a similar exercise for the hemiparetic lower extremity (LE) is effective. OBJECTIVE: The authors sought to test whether the BATRAC strategy would transfer to the legs by improving LE motor function following ten 30-minute sessions of bilateral leg training with rhythmic auditory cueing (BLETRAC). METHODS: Twenty-four chronic stroke participants, recruited from the community, were randomized to either the BLETRAC or the BATRAC intervention. Assessments were performed before (week 0) and after (week 6) training as well as 3 months later (week 18). Change in the Fugl-Meyer LE and UE subscales served as primary outcomes. Timed 10-m walk, movement parameters during treadmill walking, and a repetitive aiming task for both feet and hands were the secondary outcomes. RESULTS: Following an intention-to-treat approach, data from 21 subjects were analyzed. After training, improvements in the Fugl-Meyer LE and UE subscales tended to be better for the corresponding intervention group. The BLETRAC group also showed increases in step length during treadmill walking and performance in the repetitive foot and hand aiming tasks. No differences between the intervention groups were found at follow-up. CONCLUSIONS: This exploratory trial demonstrates that transfer of the BATRAC approach to the legs is feasible. Transient improvements of limb motor function in chronic stroke participants were induced by targeted exercise (BATRAC for the UE and BLETRAC for the LE). It may be that further periods of training would increase and maintain effects.

Gaze behavior of young and older adults during stair walking.

The authors quantitatively described gaze behavior of young (n = 10) and older (n = 10) adults during stair negotiation, which is information that is crucial for understanding the underlying visuomotor control of stair walking and the effects of aging on this control. Both age groups spent the majority of time looking at central aspects of the stairs approximately 3 steps ahead. Older adults showed less variability in the extent to which they looked ahead (p < .05), and all participants fixated the stairs for briefer periods during descent as opposed to ascent (p < .001). Older adults fixated stairs significantly longer than did young adults before stepping onto the stairs (p < .05). The authors conclude that adults need central visual information describing future stepping locations and that there are age-related differences in visual sampling that reflect changes in the visuomotor control processes subserving locomotion.