An optimized horizontal-vertical visual illusion led to significant increases in foot clearance in older adults when ascending a staircase, but the effects did not destabilize their postural stability. Inclusion of the horizontal-vertical illusion on raised surfaces (e.g., curbs) or the bottom and top stairs of staircases could improve stair ascent safety in older adults.

BackgroundGood control of trunk and pelvic movements is necessary for well controlled leg movements required to perform activities of daily living. The nature of movement coupling between the trunk and pelvis varies and depends on the type of activity. Children with cerebral palsy often have reduced ability to modulate coupling between the trunk and pelvis but movement patterns of the pelvis can be improved by training. The aim of this study was to examine how pelvis to trunk coupling changed while playing a computer game driven by pelvic rotations.MethodsOne boy with cerebral palsy diplegia played the Goblin Post Office game on the CAREN virtual rehabilitation system for six weeks. He navigated a flying dragon in a virtual cave towards randomly appearing targets by rotating the pelvis around a vertical axis. Motion of the pelvis and trunk was captured in real-time by a Vicon 612 optoelectronic system tracking two clusters of three markers attached to the sacrum and thoracic spine.ResultsConvex hull areas calculated from angle-angle plots of pelvic and trunk rotations showed that coupling increased over game training (F1,11 = 7.482, p = 0.019). Reaching to targets far from the midline required tighter coupling than reaching near targets (F1,12 = 10.619, p = 0.007).ConclusionsIncreasing coupling appears to be an initial compensation mechanism using the better controlled trunk to drive rotation of the pelvis. Co-contractions causing increased coupling are expected to reduce over longer exposure to training. The control scheme of the training game can be set to facilitate de-coupling of pelvic movements from the trunk. Using large ranges of pelvic rotation required more coupling suggesting that training of selective pelvic movements is likely to be more effective close to a neutral pelvic posture.

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Changes to foot clearance parameters as a result of highlighter presence and position suggest that stairs with high-contrast edge highlighters positioned flush with the tread edge will improve safety on stairs, particularly for those with age-related visual impairment.

yesBackground: Falls on stairs are a common and dangerous problem for older people. This series of studies\ud evaluated whether or not selected changes to the appearance of stairs could make them safer for older\ud people to negotiate.\ud Objectives: To determine the effect of (1) a step edge highlighter and its position and (2) an optimised\ud horizontal–vertical (H–V) visual illusion placed on a step riser on gait safety during stair descent and ascent.\ud Design: A series of studies using a repeated measures, laboratory-based design, investigating gait control\ud and safety in independently mobile older people.\ud Setting: The University of Bradford Vision and Mobility Laboratory.\ud Participants: Fit and healthy older people aged 60 years of age or more, independently mobile,\ud reasonably active and with normal healthy eyes and corrected vision.\ud Interventions: A step edge highlighter in a variety of offsets from the stair edge and an optimised H–V visual\ud illusion placed on the stair riser. The H–V illusion was provided on a staircase by horizontal step edge\ud highlighters on the tread edges and vertical stripes on the step risers.\ud Main outcome measures: Gait parameters that are important for safe stepping in ascent and descent,\ud particularly toe clearance during stair ascent and heel clearance during stair descent.\ud Results: The step edge highlighter increased the precision of heel clearance during stepping and its\ud positioning relative to the tread edge determined the extent of heel clearance over the tread edge.\ud Positioning the highlighter away from the tread edge, as is not uncommonly provided by friction strips,\ud decreased heel clearance significantly and led to greater heel scuffs. Although psychophysics experiments\ud suggested that higher spatial frequencies of the H–V illusion might provide greater toe clearance on stair\ud ascent, gait trials showed similar increased toe clearances for all spatial frequencies. When a 12 cycle per\ud step spatial frequency H–V illusion was used, toe clearance increases of approximately 1 cm (17.5%)\ud occurred without any accompanying changes in other important gait parameters or stability measures.\ud Conclusions: High-contrast tread edge highlighters present on steps and stairs and positioned flush with\ud the edge of the tread or as near to this as possible should improve stair descent safety in older people. A\ud H–V illusion positioned on the riser of a raised surface/walkway (e.g. kerbs) and/or the top and/or bottom\ud of a stairway is likely to increase foot clearance over the associated step/stair edge, and appears not to\ud lead to any decrement in postural stability. Thus, their use is likely to reduce trip risk and hence improve\ud stair ascent safety. The effect of the step and stair modifications should be assessed in older people with\ud visual impairment. The only other remaining assessment that could be made would be to assess fall\ud prevalence on steps and stairs, perhaps in public buildings, with and without these modifications...