Newly Acquired Fear of Falling Leads to Altered Eye Movement Patterns and Reduced Stepping Safety: A Case Study

This opportune case study describes visual and stepping behaviours of an 87 year old female (P8), both prior to, and following two falls. Before falling, when asked to walk along a path containing two stepping guides positioned before and after an obstacle, P8 generally visually fixated the first stepping guide until after foot contact inside it. However, after falling P8 consistently looked away from the stepping guide before completing the step into it in order to fixate the upcoming obstacle in her path. The timing of gaze redirection away from the target (in relation to foot contact inside it) correlated with absolute stepping error. No differences in eyesight, cognitive function, or balance were found between pre- and post-fall recordings. However, P8 did report large increases in fall-related anxiety and reduced balance confidence, supporting previously suggested links between anxiety/increased fear or falling and maladaptive visual/stepping behaviours. The results represent a novel insight into how psychological and related behavioural factors can change in older adults following a fall, and provide a possible partial rationalisation for why recent fallers are more likely to fall again in the following 12 months. These findings highlight novel possibilities for falls prevention and rehabilitation

The effects of constraining vision and eye movements on whole-body coordination during standing turns

Turning the body towards a new direction is normally achieved via a top-down synergy whereby gaze (eye direction in space) leads the upper body segments, which in turn lead the feet. These anticipatory eye movements are observable even in darkness and constraining the initial eye movements modifies the stereotyped top-down reorientation sequence. Our aim was to elucidate the relative contributions of vision and eye movements to whole-body coordination during large standing turns by observing the effects of separately removing visual information or suppressing eye movements throughout the turn. We predicted that constraining eye movements would modify the steering synergy, whereas removing vision would have little effect. We found that preventing eye movements modified both timing and spatial characteristics of axial segment and feet rotation. When gaze was fixed, gait initiation, but not axial segment rotation, was delayed in comparison to both full vision and no vision turns. When eye movements were prevented, the predictable relationship between the extent head rotation led the body and peak head angular velocity was abolished suggesting that anticipatory head movements normally subserve gaze behaviour. In addition, stepping frequency significantly reduced during the gaze fixation condition but not during the no-vision condition, suggesting that oculomotor control is linked to stepping behaviour

Route previewing results in altered gaze behaviour, increased self-confidence and improved stepping safety in both young and older adults during adaptive locomotion

Older adults with falls-risk tend to look away prematurely from targets for safe foot placement to view future hazards; behaviour associated with increased anxiety and stepping inaccuracies. We aimed to determine the effectiveness of route-previewing in reducing anxiety and optimizing gaze behaviour and stepping performance of young and older adults. Nine younger and nine older adults completed six walks with three task complexities over two sessions. Each trial used either an isolated stepping target, or a target followed by either one or two obstacles. Participants with eyes closed, on hearing a signal, opened their eyes and initiated walking (go trials) or stood previewing the route for 10s before starting (preview trials). Kinematic data were collected using a Vicon motion analysis system. Gaze behaviour was recorded using a Dikablis eye tracker. On average, both older and younger adults fixated the target for significantly longer during walking when they had previewed the route than when they had not. Self-confidence scores were also significantly higher following ‘preview trials’ than ‘go trials’. Stepping performance significantly improved following route previewing (reduced Medial lateral foot placement variability for both groups and reduced Anterior/posterior foot placement error in older adults only). These findings implicate route previewing as a potential intervention to increase self-confidence and reduce the risk of tripping in older adults

Immediate Effect of Voluntary-induced Stepping Response Training on Protective Stepping in Persons with Chronic Stroke: A Randomized Controlled Trial

Purpose: To compare the immediate effects of voluntary-induced stepping response training (VSR) and DynSTABLE perturbation training (DST) on protective stepping in patients with stroke. Methods: A randomized controlled trial (registration number: TCTR20170827001) was conducted in 34 patients with chronic stroke who were randomly allocated to the VSR (n = 17) or DST (n = 17) group. The VSR group was instructed to lean forward to induce protective stepping, while the DST group experienced support surface translation. All participants received one session of training (3 set, 10 min for each set with 10-minute rest in between). Step length, step width, number of steps and center of mass (CoM) position during protective stepping were assessed using a computer-assisted rehabilitation environment (CAREN) system prior to and immediately after training. Two-way ANOVA was used to compare between groups and times. Results: Both types of training resulted in an increase in step width, but step length increased and there was a more positive COM position exhibited following DST (p < .05) than following VSR. Single-step incidence increased, whereas multiple-step incidence decreased significantly in both groups. Only participants in the VSR group generated protective stepping with the affected leg in a larger percentage of trials (27%) after training than before training. Conclusion: Both DST and VSR led to changes in protective stepping parameters after a single session of training. VSR may be a feasible alternative to equipment-based training but requires further study. • Implication for Rehabilitation • VSR and DST trainings improved protective stepping in stroke. • Step length and CoM control at foot touchdown increased after DST training. • VSR training for 50 minutes led to increase affected stepping and reduce grasping. • Step width, affected step length, and single step increased after both trainings. • Without instrument, VSR increased steps execution and performance similar to DST

Children With Developmental Coordination Disorder Exhibit Greater Stepping Error Despite Similar Gaze Patterns and State Anxiety Levels to Their Typically Developing Peers

This study examined stepping accuracy, gaze behavior, and state-anxiety in children with (N = 21, age M = 10.81, SD = 1.89) and without (N = 18, age M = 11.39, SD = 2.06) developmental coordination disorder (DCD) during an adaptive locomotion task. Participants walked at a self-selected pace along a pathway, placing their foot into a raised rectangular floor-based target box followed by either no obstacles, one obstacle, or two obstacles. Stepping kinematics and accuracy were determined using three-dimensional motion capture, whilst gaze was determined using mobile eye-tracking equipment. The children with DCD displayed greater foot placement error and variability when placing their foot within the target box and were more likely to make contact with its edges than their typically developing (TD) peers. The DCD group also displayed greater variability in the length and width of their steps in the approach to the target box. No differences were observed between groups in any of the gaze variables measured, in mediolateral velocity of the center of mass during the swing phase into the target box, or in the levels of self-reported state-anxiety experienced prior to facing each task. We therefore provide the first quantifiable evidence that deficits to foot placement accuracy and precision may be partially responsible for the increased incidence of trips and falls in DCD, and that these deficits are likely to occur independently from gaze behavior and state-anxiety

Older adults who have previously fallen due to a trip walk differently than those who have fallen due to a slip

Studying the relationships between centre of mass (COM) and centre of pressure (COP) during walking has been shown to be useful in determining movement stability. The aim of the current study was to compare COM–COP separation measures during walking between groups of older adults with no history of falling, and a history of falling due to tripping or slipping. Any differences between individuals who have fallen due to a slip and those who have fallen due to a trip in measures of dynamic balance could potentially indicate differences in the mechanisms responsible for falls. Forty older adults were allocated into groups based on their self-reported fall history during walking. The non-faller group had not experienced a fall in at least the previous year. Participants who had experienced a fall were split into two groups based on whether a trip or slip resulted in the fall(s). A Vicon system was used to collect full body kinematic trajectories. Two force platforms were used to measure ground reaction forces. The COM was significantly further ahead of the COP at heel strike for the trip (14.3 ± 2.7 cm) and slip (15.3 ± 1.1 cm) groups compared to the non-fallers (12.0 ± 2.7 cm). COM was significantly further behind the COP at foot flat for the slip group (−14.9 ± 3.6 cm) compared to the non-fallers (−10.3 ± 3.9 cm). At mid-swing, the COM of the trip group was ahead of the COP (0.9 ± 1.6 cm), whereas for the slip group the COM was behind the COP (−1.2 ± 2.2 cm). These results show identifiable differences in dynamic balance control of walking between older adults with a history of tripping or slipping and non-fallers

Do Postural Constraints Affect Eye, Head and Arm Coordination?

If a whole-body reaching task is produced when standing or adopting challenging postures, it is unclear whether changes in attentional demands or the sensorimotor integration necessary for balance control influence the interaction between visuomotor and postural components of the movement. Is gaze control prioritized by the CNS to produce coordinated eye movements with the head and whole-body regardless of movement context? Considering the coupled nature of visuomotor and whole-body postural control during action, this study aimed to understand how changing equilibrium constraints (in the form of different postural configurations) influenced the initiation of eye, head and arm movements. We quantified the eye-head metrics and segmental kinematics as participants executed either isolated gaze shifts or whole-body reaching movements to visual targets. In total, four postural configurations were compared: seated, natural stance, with the feet together (narrow stance), or while balancing on a wooden beam. Contrary to our initial predictions, the lack of distinct changes in: eye-head metrics, timing of eye, head and arm movement initiation, and gaze accuracy, in spite of kinematic differences, suggests that the CNS integrates postural constraints into the control necessary to initiate gaze shifts. This may be achieved by adopting a whole-body gaze strategy that allows for the successful completion of both gaze and reaching goals

AGE-RELATED EFFECTS OF INCREASING POSTURAL CHALLENGE ON EYE MOVEMENT ONSET LATENCIES TO VISUAL TARGETS

When a single light cue is given in the visual field, our eyes orient towards it with an average latency of 200 ms. If a second cue is presented at or around the time of the response to the first, a secondary eye movement occurs that represents a re-orientation to the new target. While studies have shown that eye movement latencies to ‘single-step’ targets may or may not be lengthened with age, secondary eye-movements (during ‘double-step’ displacements) are significantly delayed with increasing age. The aim of this study was to investigate if the postural challenge posed simply by standing (as opposed to sitting) results in significantly longer eye movement latencies in older adults compared to the young. Ten young (65 years) participated in the study. They were required to fixate upon a central target and move their eyes in response to 2 types of stimuli: 1) a single-step perturbation of target position either 15º to the right or left, and 2) a double-step target displacement incorporating an initial target jump to the right or left by 15º, followed after 200 ms, by a shift of target position to the opposite side (e.g., +15º then -15º). All target displacement conditions were executed in sit and stand positions with the participant at the same distance from the targets. Eye movements were recorded using electro-oculography. Older adults did not show significantly longer eye movement latencies than the younger adults for single-step target displacements, and postural configuration (stand compared to sit) had no effect upon latencies for either group. We categorised double-step trials into those during which the second light changed after or before the onset of the eye shift to the first light. For the former category, young participants showed faster secondary eye shifts to the second light in the standing position, while the older adults did not. For the latter category of double-step trial, young participants showed no significant difference between sit and stand secondary eye movement latencies, but older adults were significantly longer standing compared to sitting. The older adults were significantly longer than the younger adults across both postural conditions, regardless of when the second light change occurred during the eye shift to the first light. We suggest that older adults require greater time and perhaps attentional processes to execute eye movements to unexpected changes of target position when faced with the need to maintain standing balance. Keywords: Balance, Ageing, Gaze, Electro-oculography, Target perturbations

Children With Developmental Coordination Disorder Show Altered Visuomotor Control During Stair Negotiation Associated With Heightened State Anxiety

Safe stair negotiation is an everyday task that children with developmental coordination disorder (DCD) are commonly thought to struggle with. Yet, there is currently a paucity of research supporting these claims. We investigated the visuomotor control strategies underpinning stair negotiation in children with (N = 18, age = 10.50 ± 2.04 years) and without (N = 16, age = 10.94 ± 2.08 years) DCD by measuring kinematics, gaze behavior and state anxiety as they ascended and descended a staircase. A questionnaire was administered to determine parents' confidence in their child's ability to safely navigate stairs and their child's fall history (within the last year). Kinematics were measured using three-dimensional motion capture (Vicon), whilst gaze was measured using mobile eye-tracking equipment (Pupil labs). The parents of DCD children reported significantly lower confidence in their child's ability to maintain balance on the stairs and significantly more stair-related falls in the previous year compared to the parents of typically developing (TD) children. During both stair ascent and stair descent, the children with DCD took longer to ascend/descend the staircase and displayed greater handrail use, reflecting a more cautious stair negotiation strategy. No differences were observed between groups in their margin of stability, but the DCD children exhibited significantly greater variability in their foot-clearances over the step edge, which may increase the risk of a fall. For stair descent only, the DCD children reported significantly higher levels of state anxiety than the TD children and looked significantly further along the staircase during the initial entry phase, suggesting an anxiety-related response that may bias gaze toward the planning of future stepping actions over the accurate execution of an ongoing step. Taken together, our findings provide the first quantifiable evidence that (a) safe stair negotiation is a significant challenge for children with DCD, and that (b) this challenge is reflected by marked differences in their visuomotor control strategies and state anxiety levels. Whilst it is currently unclear whether these differences are contributing to the frequency of stair-related falls in children with DCD, our findings pave the way for future research to answer these important questions

Straight-sided beer and cider glasses to reduce alcohol sales for on-site consumption: A randomised crossover trial in bars.

BACKGROUND: Straight-sided glasses can slow the rate of lager consumption in a laboratory setting compared with curved glasses. Slower drinking rates may lower overall alcohol consumption. Glass shape is therefore a potential target for intervention. The aim of this randomised crossover trial was to estimate the impact of serving draught beer and cider in straight-sided glasses, compared with usual, predominantly curved glasses, on alcohol sales for on-site consumption in bars. METHODS: Twenty-four bars in England completed two intervention periods (A) and two control periods (B) in a randomised order: 1) BABA; 2) BAAB; 3) ABBA; or 4) ABAB. Each period lasted two weeks and involved serving draught beer and cider in either straight-sided glasses (A) or the venue's usual glasses (≥75% curved; B). The primary outcome was the mean volume (in litres) of draught beer and cider sold weekly, compared between A and B periods using a paired-samples t-test on aggregate data. A regression model adjusted for season, order, special events, and busyness. FINDINGS: Mean weekly volume sales of draught beer and cider was 690·9 L (SD 491·3 L) across A periods and 732·5 L (SD 501·0 L) across B periods. The adjusted mean difference (A minus B) was 8·9 L per week (95% CI -45·5 to 63·3; p = 0·737). INTERPRETATION: This study provides no clear evidence that using straight-sided glasses, compared with usual, predominantly curved glasses, reduces the volume of draught beer and cider sold for on-site consumption in bars