To Step or To Spring: The Influence of State Anxiety on Perceptual Judgments and Executed Action

To Step or To Spring: The Influence of State Anxiety on Perceptual Judgments and Executed Actio

Performance under varying constraints in Developmental Coordination Disorder (DCD): Difficulties and compensations

Purpose of Review Developmental coordination disorder is by very nature a disorder of movement and coordination. The constraints-based approach to motor control advocates the idea that the environment, the task and the individual can all constrain and promote movement/coordination. The purpose of this review is to describe factors which have been shown to explain the movement patterns in developmental coordination disorder (DCD) and discuss these in light of the constraints-based approach. Recent Findings Recent findings, within the DCD field, considering the perception-action relationship, the control of movement, the role of vision and individual differences in DCD can all be considered under the constraints-based which allows us to consider all factors involved in movement. Summary This paper has demonstrated the usefulness of the constraints-based approach in considering DCD and has also raised important questions regarding how we group and describe these individuals

Why are older adults more at risk as pedestrians? a systematic review

Objective To explore factors that could explain why older adults are more at risk at the roadside. Background The physical and psychological health benefits of walking have been well-established, leading to the widespread promotion of walking amongst older adults. However, walking can result in an increased risk of injury as a pedestrian at the roadside, which is a greater risk for older adults who are overrepresented in pedestrian casualty figures. Method Relevant databases were searched up to January 2020. All peer-reviewed journals that presented data on healthy older adults and some aspect of road crossing or roadside behavior were included. A total of 142 papers were assessed and 60 met the inclusion criteria. Results Identified papers could be grouped into three areas: crossing at a designated crossing place; crossing with no designated crossing place; perceptions or behaviors. Conclusion Multiple individual (attitudes, perceived behavioral control, walking time, time-to-arrival judgments, waiting endurance, cognitive ability), task (vehicle size, vehicle speed, traffic volume), and environmental (road layout, time of day, weather) constraints influence road crossing in older adulthood. Application Accessibility of designated crossing areas needs to be addressed by ensuring sufficient time to cross and nonrestrictive waiting times. Signalized crossings need to be simplified and visibility increased. Where there is no designated crossing place, a reduction in speed limit alongside the provision of pedestrian islands to provide “pause” places are needed. Educational-based programs may also help ensure safety of older adults where there is no designated crossing place

The lived experience of crossing the road when you have Developmental Coordination Disorder (DCD): the perspectives of parents of children with DCD and adults with DCD

Pedestrians are one of the most vulnerable groups at the roadside, furthermore, previous research has demonstrated perceptual-motor limitations in individuals with DCD which may put these individuals at even more at risk in the context of road crossing. However, it is unclear whether this is the lived experience of these individuals at the roadside. Furthermore, difficulties with road crossing and safety have been found in other neurodevelopmental disorders but the impact this might have on an individual with co-occurring difficulties is unknown. Therefore, we utilised a questionnaire to survey the lived experience of adults with DCD and parents of children with DCD with the specific objectives of describing behaviours exhibited by adults and children with DCD (the latter reported by parents) at the roadside and to determine the how these individuals perceive road crossing actions. For each of these we compared different co-occurrence groups. We also had one final objective which was not focussed on road crossing but more on the general perception of accidents and unrealistic optimism. Individuals with co-occurrences which have previously been linked to unsafe crossing behaviours (i.e. ADHD, ASD and LD) reported a greater regularity of dangerous looking behaviour (forgetting to look, running without looking) and visibility (crossing between cars, crossing when you can’t see), these adults and the parents of these children were seemingly aware of the risky nature of these behaviours. When asked ‘why’ crossing ability might be different, perceptual and motor difficulties alongside heightened awareness of risk and lowered awareness of risk were all cited by participants. Unrealistic optimism was not an explanation for the risky behaviour in adults with DCD and in fact, these adults demonstrated a clear understanding of the likelihood of accidents. The findings of this study suggest that road crossing is perceived to be more challenging for both children and adults with DCD and this needs to be taken into account when considering remediation for this group

The ‘why’ of reaching: second-order planning across the adult lifespan

Second-order planning, planning which takes into account imminent and subsequent task demands, has been shown to be essential during everyday movement. For example, the kinematics of a ‘reach to an object’ action have been shown to be linked to the intended goal for the object (the prior intention). However, it is unclear whether this type of second-order planning for prior intention is preserved during aging, or indeed how this differs across the adult lifespan. Kinematics of a reach action preceding four prior intentions, place in a ‘tight’ hole, place in a ‘loose’ hole, throw or lift were measured in 122 aged from 20-81 years. The kinematics of the reach movement demonstrated that all participants tailored their reach movement to the prior intention, with the deceleration period of the reach discriminating across groups. The 20s and 30s group showed a different deceleration period during the reach for tight versus loose place prior intentions, this was not seen after 39 years of age and the 70+ group showed no discrimination across the deceleration period for the four prior intentions. When considering movement efficiency of the place actions we found it could be predicted by age and that this relationship was mediated by discrimination across the deceleration period. This study demonstrates that a clear difference is seen in the way in which second-order planning is used across the lifespan and that this has implications for movement efficiency

When an object appears unexpectedly: foot placement during obstacle circumvention in children and adults with Developmental Coordination Disorder

Adjustments to locomotion to avoid an obstacle require a change to the usual pattern of foot placement, i.e. changes to step length and/or step width. Previous studies have demonstrated a difficulty in individuals with Developmental Coordination Disorder (DCD) in controlling stability while both stepping over and while circumventing an obstacle. In a previous study we have considered the way in which individuals with DCD prepare for the possibility of an obstacle appearing (Wilmut and Barnett, 2017). Using a parallel data set from this same task on the same individuals the aim of the current study was to investigate the exact nature of changes in foot placement during obstacle avoidance, as this was not clear from previous work. Children and adults aged from 7 to 34 years of age took part in the study. Forty-four met the criteria for a diagnosis of DCD and there were 44 typically developing (TD) age and gender matched controls. Participants walked at a comfortable pace down an 11m walkway; on 6 out of 36 trials a ‘gate’ closed across their pathway which required circumvention. These 6 ‘gate close’ trials were analysed for this study. The number and magnitude of step length and step width adjustments were similar across the DCD and TD groups, however, the younger children (7-11yrs) made a greater number of early adjustments compared to the older children and adults (12-34 years of age). In contrast the adults made a greater number of adjustments later in the movement compared to the children. In terms of foot placement adjustments a clear preference was seen across all participants to use adjustments which resulted in reducing step length, stepping away from the obstacle and a combination of these. Apart from subtle differences, the individuals with DCD make step placements to circumvent an obstacle in line with their peers. It is suggested that the choice of foot placement strategy in individuals with DCD, although in line with their peers, may not be optimal for their level of motor ability

When an object appears unexpectedly: anticipatory movement and object circumvention in individuals with and without Developmental Coordination Disorder

​Obstacles often appear unexpectedly in our pathway and these require us to make adjustments to avoid collision. Previous research has demonstrated that healthy adults will make anticipatory adjustments to gait where they have been told there is the possibility of an obstacle appearing. One population that may find this type of anticipatory movement difficult is individuals with Developmental Coordination Disorder (DCD). The current study considered how individuals with and without DCD adjust to the possibility of an obstacle appearing which would require circumvention. Forty four individuals with DCD and 44 agematched controls (aged from 7-34 years of age) walked down an 11m walkway under three conditions. Initially they were told this was a clear pathway and nothing in the environment would change (1, no possibility of an obstacle, no obstacle). They then performed a series of trials in which a gate may (2, possibility of an obstacle, obstacle) or may not (3, possibility of an obstacle, no obstacle) partially obstruct their pathway. We found that all participants increased medio-lateral trunk acceleration when there was the possibility of an obstacle but before the obstacle appeared, in addition the typical adults and older children also increased step width. When describing circumvention we found that the younger children showed an increase in trunk velocity and acceleration in all three directions compared to older children and adults. We also found that the individuals with DCD adjusted their path sooner and deviated more than their peers. The degree of adjustment to step width in anticipation of an obstacle was related to later medio-lateral velocity and timing of the deviation. Therefore, the lack of ‘readying’ the system where there is the possibility of an obstacle appearing seen in the individuals with DCD and the younger typical children may explain the increased mediolateral velocity seen during circumvention

Investigating motor planning in children with DCD: Evidence from simple and complex grip-selection tasks

Several studies suggest that children with Developmental Coordination Disorder (DCD) may be able to plan simple movements as well as their peers, but experience increasing difficulties as the movements become complex. The present study aimed to clarify the nature of motor planning in DCD, including a putative deficit, by being the first to investigate motor planning using converging measures of simple and complex motor planning in a single sample of children with DCD. Boys aged between 8 – 12 years with (n = 10) and without DCD (n = 17) completed three commonly used ‘simple’ (bar grasping, sword, and bar transport tasks) measures and one ‘complex’ (octagon task) measure of end-state-comfort (ESC), a classic measurement of motor planning ability. To achieve ESC when manipulating an object, a person may choose to start with an uncomfortable grip in order to end the movement in a comfortable position. Results indicate that the participants with DCD planned for ESC as efficiently as their peers when performing the ‘simple’ measures of ESC but were significantly less likely to end their performances in ESC than those without DCD for the more ‘complex’ octagon task. Taken together, our data suggest that school-aged children with DCD may be able to plan simple movements as efficiently as their peers, but have more difficulty doing so for multi-movement or complex sequences. Based on the assumption that the efficiency of such motor planning is dependent on the integrity of internal modelling systems, we argue that our study provides indirect support for the internal modelling deficit hypothesis

Constraints on motor planning across the lifespan: Physical, cognitive and motor factors

Skilled adult movers plan for a comfortable end position even when this requires an uncomfortable start position (end-state-comfort effect). This ability declines in late adulthood and has been linked to age-related differences in cognitive functioning. Other factors, which may also drive difference in motor planning in later adulthood have not been systematically examined. These include perceptions of comfort and levels of motor imagery ability (one’s ability to mentally simulate action / predict the outcome of action). Therefore, this study investigated the constraints on movement planning across the lifespan, including executive functions, general motor ability, physical constraints to movement and motor imagery ability. One hundred and twenty-two participants aged 20-81 years completed an end-state-comfort task with increasing levels of complexity. Individuals’ executive functions, motor control, motor imagery ability and perceived rotation span were also examined. Age-related decline was shown in planning for sequential movements but not in simple single-step movements. Motor planning demonstrated an age-related difference which was associated with an increasing number of constraints as age increased, and in older adults chronological age influenced the effect of each constraint on motor planning. Age-related difference in motor planning may reflect effective compensatory strategies in response to differing constraints in motor imagery ability, executive functions, perceived rotation span and general speed and accuracy of movement as we age

Adaptations to walking on an uneven terrain for individuals with and without Developmental Coordination Disorder

​Given the importance of walking in everyday life, understanding why this is challenging for some populations is particularly important. Studies focusing on gait patterns of individuals with Developmental Coordination Disorder (DCD) have shown that whilst increased variability is characteristic of walking patterns for this group, differences in spatio-temporal gait variables seem only to arise when task demands increase. However, these differences occur under rather artificial conditions, for example using a treadmill. The aim of this study, therefore was to examine the step characteristics of individuals with and without DCD whilst walking along an irregular terrain. Thirty-five individuals with DCD aged 8-32 years and 35 age and gender-matched controls participated in this study. Participants were divided into 3 age groups; 8-12years (n = 12), 13-17years (n =12) and 18-32years (n=11). Participants walked up and down a 6m walkway for two minutes on two terrains: level and irregular. VICON 3D motion analysis was used to extract measures of foot placement, velocity and angle of the head and trunk. Results showed that both groups adapted their gait to negotiate the irregular terrain, but the DCD group were more affected than their TD peers; walking significantly slower with shorter, wider steps and inclining their head more towards the ground. This suggests an adaptive approach used by individuals with DCD to preserve stability and increase visual sampling whilst negotiating an irregular terrain