Visual contribution to walking in children with Developmental Coordination Disorder

Spatial Accuracy and Variability in Dart Throwing in Children with Developmental Coordination Disorder and the Relationship with Ball Skill Items

The present study aimed to examine precision and variability in dart throwing performance and the relationships between these outcomes and bouncing, throwing and catching tasks in children with and without DCD. Children between the ages of 8 and 10 years (n = 165) were classified according to results obtained on the Movement Assessment Battery for Children (MABC-2) and divided into three groups: 65 children with severe DCD (s-DCD), 45 with moderate DCD (m-DCD) and 55 typically developing children (TD). All children performed the dart throwing test and the ball skill items of the Performance and Fitness Test (PERF-FIT). The accuracy and variability of dart throwing tasks were significantly different between TD and s-DCD (p < 0.01), and also between m-DCD and s-DCD (p < 0.01). Participants with s-DCD were also found to perform significantly worse on all PERF-FIT ball skill items than m-DCD (p < 0.001), and m-DCD were significantly poorer than TD (p < 0.001). The dart score and coefficient of variation of the long-distance task appear to be significant predictors for the ball skills and explain between 24 to 29% of their variance. In conclusion, poor results in aiming tasks using darts in children with DCD corroborate with the explanation of deficits in predictive control since the tasks require ballistic movements.

Motor Skills and Visual Deficits in Developmental Coordination Disorder: A Narrative Review

BACKGROUND

Developmental coordination disorder (DCD) is a developmental disorder in which numerous comorbidities seem to coexist, such as motor and visual impairment and some executive functions; Methods: A narrative review on motor and visual deficits in children with DCD was carried out; Results and Discussion: Fine and gross motor skills are affected in children with DCD. In addition, they seem to be related to visual deficits, such as difficulty in visual perception, sensory processing and visual memory. Limitations have also been found in accommodation. Interventions in children with DCD should be aimed at improving both aspects, since vision affects motor skills and vice versa; Conclusions: In children with DCD, who present a marked deficit in global shape processing, it causes an association between deficiencies in visual perception and motor skills.

[Essential features for obtaining the biomechanical pattern of gait in healthy children. A systematic review]

The gait patter in childhood is constantly changing as a result of the neuro-anatomical maturation due to growth, for this reason we propose to identify from published studies and the motion capture method, the essential features for obtaining the biomechanical pattern of gait in children. A search for scientific articles was carried out in Scopus, SciELO, PudMed and PEDro where gait is evaluated in subjects under 18 years old, based on motion capture methods and biomechanical parameters. The results showed that from 7 to 9 years old the child acquires the definitive gait pattern, the most used motion capture method was Vicon, with the use of video, force platform and electromyography and the parameters used were the spatial, temporal, spatial-temporal, kinematic, kinetic and electromyographic.

Behavioral and Neuroimaging Research on Developmental Coordination Disorder (DCD): A Combined Systematic Review and Meta-Analysis of Recent Findings

AIM

The neurocognitive basis of Developmental Coordination Disorder (DCD; or motor clumsiness) remains an issue of continued debate. This combined systematic review and meta-analysis provides a synthesis of recent experimental studies on the motor control, cognitive, and neural underpinnings of DCD.

METHODS

The review included all published work conducted since September 2016 and up to April 2021. One-hundred papers with a DCD-Control comparison were included, with 1,374 effect sizes entered into a multi-level meta-analysis.

RESULTS

The most profound deficits were shown in: voluntary gaze control during movement; cognitive-motor integration; practice-/context-dependent motor learning; internal modeling; more variable movement kinematics/kinetics; larger safety margins when locomoting, and atypical neural structure and function across sensori-motor and prefrontal regions.

INTERPRETATION

Taken together, these results on DCD suggest fundamental deficits in visual-motor mapping and cognitive-motor integration, and abnormal maturation of motor networks, but also areas of pragmatic compensation for motor control deficits. Implications for current theory, future research, and evidence-based practice are discussed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, identifier: CRD42020185444.

Effect of Motor Imagery Training on Motor Learning in Children and Adolescents: A Systematic Review and Meta-Analysis

Background: There is an urgent need to systematically analyze the growing body of literature on the effect of motor imagery (MI) training in children and adolescents. Methods: Seven databases and clinicaltrials.gov were searched. Two reviewers independently screened references and full texts, and extracted data (studies’ methodology, MI elements, temporal parameters). Two studies were meta-analyzed providing the standard mean difference (SDM). Selected studies were evaluated with the risk of bias (RoB) and GRADE tools. Results: A total of 7238 references were retrieved. The sample size of the 22 included studies, published between 1995 and 2021, ranged from 18 to 136 participants, totaling 934 (nine to 18 years). Studies included healthy pupils, mentally retarded adolescents, children with motor coordination difficulties or with mild mental disabilities. The motor learning tasks focused on upper, lower and whole body movements. SMDs for the primary outcome of pooled studies varied between 0.83 to 1.87 (95% CI, I², T² varied 0.33–3.10; p = 0.001; 0–74%; 0–0.59). RoB varied between some concerns and high risk. GRADE rating was low. Conclusions: MI combined with physical practice (PP) might have a high potential for healthy and impaired children and adolescents. However, important reporting recommendations (PETTLEP, TIDieR, CONSORT) should be followed. The systematic review was registered with PROSPERO: CRD42021237361.

Young Adults With Developmental Coordination Disorder Adopt a Different Visual Strategy During a Hazard Perception Test for Cyclists

Cycling in traffic requires a combination of motor and perceptual skills while interacting with a dynamic and fast-changing environment. The inferior perceptual-motor skills in individuals with developmental coordination disorder (DCD) may put them at a higher risk for accidents. A key skill to navigate in traffic is to quickly detect hazardous situations. This perceptual-cognitive skill was investigated in young adults with DCD using simulated traffic situations in a hazard perception test in cycling. Nine individuals with DCD (age: 23.0 ± 3.8) and nine typically developing (TD) individuals (age: 24.6 ± 3.5) participated in the study and completed the test while their gaze was tracked using a remote eye tracking device. A questionnaire was used to determine cycling experience and the perception of cycling and anticipation skill in traffic. Despite a longer period to master the motor skill of cycling, individuals with DCD reported to be able to safely cycle in traffic around the same age as TD young adults. In the hazard perception test, individuals with DCD fixated the hazards later, less frequently and for a shorter duration than the TD participants, however, the participants with DCD did not wait longer to react to the hazard than the TD participants. Interestingly, individuals with DCD rated the traffic situations in the test as significantly more dangerous than the TD participants. In conclusion, the differences exposed in the hazard perception test may imply an increased risk of accidents in individuals with DCD. In further research and practice it is recommended that both the motor and the perceptual aspects of cycling are addressed.

Influence of Stochastic Resonance on Manual Dexterity in Children With Developmental Coordination Disorder: A Double-Blind Interventional Study

Background: There is increasing evidence that the stochastic resonance (SR) phenomenon provided by subthreshold mechanical noise stimulation improves the sensory-motor system. However, the effect of SR on children with developmental coordination disorder (DCD) is unclear. The purpose of this study was to assess whether SR activated by subthreshold vibrotactile noise stimulation of the wrist influences manual dexterity in children with DCD.

Methods: A double-blind interventional study was conducted. Participants were 30 children (age: 9.3 ± 1.44 years, range 6–11 years; 27 male, three female; 25 right-handed, five left-handed) meeting DCD diagnostic criteria in DSM-5. The manual dexterity test was administered the day before SR intervention (baseline-data). SR was elicited using subthreshold vibrotactile noise stimulation at 60% of the vibrotactile threshold measured at the wrist. SR was delivered two times and the manual dexterity test was administered during each SR stimulation block (SR-on condition) and after each SR stimulation block (SR-off), for a total of four measurements. Target outcomes were the component score, the standard score, and the percentile score of the manual dexterity test.

Results: The manual dexterity test scores in the SR-on condition were significantly improved compared to scores at the baseline and in the SR-off condition (p < 0.001).

Conclusions: The present study showed that subthreshold noise stimulation eliciting SR significantly improved manual dexterity outcomes in children with DCD during stimulation but not after stimulation. Future studies will need to investigate the carry-over effects of SR stimulation.

Balance control in individuals with developmental coordination disorder: A systematic review and meta-analysis

BACKGROUND

Although it is recognized that the majority of children with developmental coordination disorder (DCD) have balance deficits, comprehensive insights into which balance domains are affected, are still lacking in literature.

RESEARCH QUESTION

To what extent is balance control deficient in individuals with DCD compared to controls?

METHODS

Pubmed, Scopus and Web of Science were systematically searched. Risk of bias was assessed with the Scottish Intercollegiate Guidelines Network checklist for case-control studies. Mean and standard deviations characterizing balance control were extracted to calculate standardized mean differences (SMD) and pooled, if possible, using Review Manager.

RESULTS

The results of 31 studies (1152 individuals with DCD, 1103 typically developing (TD) peers, mean age 10.4 years old) were extracted of which 17 were used for meta-analysis. The mean SMD for the balance subscale of the Movement Assessment Battery for Children was 1.63 (pooled 95 %CI =[1.30;1.97]), indicating children with DCD to perform significantly poorer than their TD peers. Force plate studies also revealed that children with DCD present with a larger sway path during bipedal stance with eyes closed (pooled mean SMD = 0.55; 95 %CI=[0.32;0.78]). Children with DCD tend to have direction-specific limited stability limits and task-independent delayed onset of anticipatory postural adjustments.

INTERPRETATION

Children with DCD perform poorer on different domains of balance compared to TD peers. Future research should focus on comprehensive balance assessment in these children, preferably using a longitudinal design.

Differences in walking and running gait in children with and without developmental coordination disorder: A systematic review and meta-analysis

BACKGROUND

Developmental coordination disorder (DCD) is a common motor skills disorder in children. Although gait changes are often reported clinically, affecting children's participation in play and sport, there has been no synthesis of research evidence comparing gait of children with and without DCD. Thus, the aim of this research was to determine differences in gait between children with and without DCD METHODS: A search of electronic databases (AMED, CINAHL, Cochrane Library, Embase, Medline, SPORTDiscus, & Web of Science) was conducted from inception to August 2019 for studies comparing walking and/or running gait of children with and without DCD. The McMaster Critical Appraisal Form for Quantitative Studies was used to assess risk of bias amongst included studies. Meta-analysis was completed on measures with four or more homogenous outcomes.

RESULTS

20 studies fulfilled the inclusion criteria and were eligible for review - three of which were pre-post designs, and 17 were cross-sectional designs. Data was extracted in five domains: kinetics, kinematics, physical function, electromyography, and temporospatial parameters. Meta-analysis was performed on one outcome measure - the 6 min Walk Test (6MWT), finding that children with DCD walked significantly shorter distances, indicating reduced endurance in walking gait. Other statistically significant results all favoured typically developing children, however there is little consistency between studies.

CONCLUSION

Although a clear gait pattern for children with DCD is not evident, functional deficits appear to be present in endurance and cardiorespiratory fitness. The current evidence base for gait changes in DCD is currently low-level, and further high quality research is warranted.

PROSPERO REGISTRATION NUMBER

CRD42018106791.

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.

Combined action observation and motor imagery facilitates visuomotor adaptation in children with developmental coordination disorder

The internal modelling deficit (IMD) hypothesis suggests that motor control issues associated with Developmental Coordination Disorder (DCD) are the result of impaired predictive motor control. In this study, we examined the benefits of a combined action observation and motor imagery (AO + MI) intervention designed to alleviate deficits in internal modelling and improve eye-hand coordination during a visuomotor rotation task. Twenty children with DCD were randomly assigned to either an AO + MI group (who watched a video of a performer completing the task whilst simultaneously imagining the kinaesthetic sensations associated with action execution) or a control group (who watched unrelated videos involving no motor content). Each group then attempted to learn a 90° visuomotor rotation while measurements of completion time, eye-movement behaviour and movement kinematics were recorded. As predicted, after training, the AO + MI group exhibited quicker completion times, more target-focused eye-movement behaviour and smoother movement kinematics compared to the control group. No significant after-effects were present. These results offer further support for the IMD hypothesis and suggest that AO + MI interventions may help to alleviate such deficits and improve motor performance in children with DCD.

Manual Dexterity is not Related to Media Viewing but is Related to Perceptual Bias in School-Age Children

Although the media can have both negative and positive effects on children’s cognitive and motor functions, its influence on their perceptual bias and manual dexterity is unclear. Thus, we investigated the association between media viewing time, media preference level, perceptual bias, and manual dexterity in 100 school-aged children. Questionnaires completed by children and their parents were used to ascertain media viewing time and preference levels. Perceptual bias and manual dexterity were measured using the visual-tactile temporal order judgment task and Movement Assessment Battery for Children—2nd edition, respectively. There were significant positive correlations between age and media viewing time and between media viewing time and media preference level. There was also a significant negative correlation between visual bias and manual dexterity. Hierarchical multiple regression analysis revealed that increasing visual bias was a significant predictor of decreasing manual dexterity. Further, children with low manual dexterity showed significant visual bias compared to those with high manual dexterity, when matched for age and gender. The present results demonstrated that, in school-aged children, although viewing media was not associated with perceptual bias and manual dexterity, there was a significant association between perceptual bias and manual dexterity.

Subthreshold Vibrotactile Noise Stimulation Immediately Improves Manual Dexterity in a Child With Developmental Coordination Disorder: A Single-Case Study

Developmental coordination disorder (DCD) is the most common childhood movement disorder. It is characterized by clumsiness of fine and gross motor skills in developing children. Children with DCD have low ability to effectively use tactile information for movements, instead relying on visual information. In addition, children with DCD have deficits in visuo-motor temporal integration, which is important in motor control. These traits subsequently lead to clumsiness of movements. Conversely, however, imperceptible vibrotactile noise stimulation (at 60%-intensity of the sensory threshold) to the wrist provides stochastic resonance (SR) phenomenon to the body, improving the sensory and motor systems. However, the effects of SR have not yet been validated in children with DCD. Thus, we conducted a single case study of a 10-year-old boy with a diagnosis of DCD to investigate the effect of SR on visual dependence, visuo-motor temporal integration, and manual dexterity. SR was provided by vibrotactile noise stimulation (at an intensity of 60% of the sensory threshold) to the wrist. Changes in manual dexterity (during the SR on- and off-conditions) were measured using the manual dexterity test of the Movement Assessment Battery for Children-2nd edition. The point of subjective equality measured by visual or tactile temporal order judgment task served as a quantitative indicator reflecting specific sensory dependence. The delay detection threshold and steepness of delay detection probability curve, which were measured using the delayed visual feedback detection task, were used as quantitative indicators of visuo-motor temporal integration. The results demonstrated alleviated visual dependence and improved visuo-motor temporal integration during the SR on-conditions rather than the SR off-conditions. Most importantly, manual dexterity during the SR on-conditions was significantly improved compared to that during the SR off-conditions. Thus, the present results highlighted that SR could contribute to improving poor movement in children with DCD. However, since this was a single case study, a future interventional study with a large sample size is needed to determine the effectiveness of SR for children with DCD.

Automated Fine Motor Evaluation for Developmental Coordination Disorder

Developmental coordination disorder (DCD) is a type of motor learning difficulty that affects five to six percent of school-aged children, which may have a negative impact on the life of the sufferers. Timely and objective diagnosis of DCD are important for the success of the intervention. The present evaluation methods of DCD rely heavily on the observational analysis of occupational therapists and physiotherapists, who score the performance when children conduct some designed tasks. However, these methods are expensive, subjective, and are not easy to expand to a larger population. A fine motor evaluation system (FMES) is proposed with two views of cameras to record children's performance, when they carry out three fine motor tasks. Automated algorithms are developed to perform automated scoring of fine motor skill. The automated algorithms include task localization and individual task evaluation. The purpose of task localization is to detect each task and extract segments belonging to each task from the original video that includes multiple segments of different tasks. A convolutional neural network with temporal filtering is used to do frame-wise classification, and a boundary localization algorithm is proposed to localize each task segment. For individual task evaluation, the extracted video segments of task 1 and task 2 are evaluated based on the proposed feature extraction and time positioning algorithm, and the paper drawings of task 3 are evaluated based on image processing. The proposed methods are validated on a diverse population of children with or without DCD by comparing automated scoring with manual scoring from a professional evaluator. The experimental results suggest that the proposed methods can effectively achieve fine motor evaluation for DCD assessment. Besides, our system is a low-cost solution, and the evaluation methods developed are automated, objective, and can be suited for large population evaluation and analysis.

Movement Control Strategies in a Dynamic Balance Task in Children With and Without Developmental Coordination Disorder

Our study aimed to analyze movement control strategies using predefined criteria for amplitude and differences in these strategies between children with and without DCD. Children with (n = 28) and without DCD (n = 15) were included. A video-observation-tool was used to score the moving body parts during a Wii Fit slalom task over multiple time points. Two-step cluster analysis was used to extract distinct movement strategies. Two different movement strategies were identified that were independently validated by a measure of task performance and a subjective mark of quality of the movement. Initial differences between groups and changes over time toward the more successful strategy were found in both groups, albeit in a different percentage. This study shows that the more efficient movement strategy is seen in the majority of the TD children and only in a small number of children with DCD, even after practice.

Effects of practice on visual finger-force control in children at risk of developmental coordination disorder

BACKGROUND

The production of finger force control is essential for a large number of daily activities. There is evidence that deficits in the mechanisms of accuracy and control of finger force tasks are associated with children's motor difficulties.

OBJECTIVE

To compare the effect of practice of an isometric finger force/torque task between children with significant movement difficulty and those with no difficulty movement.

METHODS

Twenty-four children aged between 9 and 10 years (12 at risk of developmental coordination disorder and 12 with no movement difficulty - typically developing children) were asked to produce finger force/torque control in a continuous and constant 25% of maximum voluntary torque with visual feedback during 15s. Practice was given during five consecutive days with 15 trials per day. After the practice with visual feedback, children were asked to perform five trials without visual feedback. In these trials, feedback was removed 5s after the start of the trial.

RESULTS

Typically developing children were consistently more accurate in maintaining finger force/torque control than those children at risk of developmental coordination disorder. Children from both groups improved the performance in the task according to practice sessions. Also, children at risk of developmental coordination disorder poorly performed the task without visual feedback as they did when visual feedback was available.

CONCLUSION

The present study give support to the idea that movement difficulty is associated with finger force/torque control and children at risk of developmental coordination disorder can improve finger force/torque control with practice when visual feedback is available.

The State of the Science on Sensory Factors and Their Impact on Daily Life for Children: A Scoping Review

The objective of this study was to identify and synthesize research about how sensory factors affect daily life of children. We designed a conceptual model to guide a scoping review of research published from 2005 to October 2014 (10 years). We searched MEDLINE, CINAHL, and PsycINFO and included studies about sensory perception/processing; children, adolescents/young adults; and participation. We excluded studies about animals, adults, and review articles. Our process resulted in 261 articles meeting criteria. Research shows that children with conditions process sensory input differently than peers. Neuroscience evidence supports the relationship between sensory-related behaviors and brain activity. Studies suggest that sensory processing is linked to social participation, cognition, temperament, and participation. Intervention research illustrates the importance of contextually relevant practices. Future work can examine the developmental course of sensory processing aspects of behavior across the general population and focus on interventions that support children's sensory processing as they participate in their daily lives.

Factorial Validity of the Movement Assessment Battery for Children-2nd Edition (MABC-2) in 7-16-Year-Olds

The Movement Assessment Battery for Children-2nd Edition (MABC-2) is a test of motor development, widely used in clinical and research settings. To address which motor abilities are actually captured by the motor tasks in the two age versions of the MABC-2, the AB2 for 7- 10-year-olds and the AB3 for 11- 16-year-olds, we examined AB2 and AB3 factorial validity. We conducted confirmatory factor analysis (SPSS AMOS 22.0) on data from the test's standardization samples of children aged 7-10, n = 483, and 11-16, n = 674, in order to find the best fitting models. The covariance matrix of AB2 and AB3 fit a three-factor model that included tasks of manual dexterity, aiming and catching, and balance. However, factor analytic models fitting AB2 and AB3 did not involve the dynamic balance tasks of hopping with the better leg and hopping with the other leg; and the drawing trail showed very low factor validity. In sum, both AB2 and AB3 of the MABC-2 test are able to discriminate between the three specific motor abilities; but due to questionable psychometric quality, the drawing trail and hopping tasks should be modified to improve the construct validity for both age versions of the MABC-2.

Feasibility of Motor Imagery Training for Children with Developmental Coordination Disorder - A Pilot Study

Children with Developmental Coordination Disorder (DCD) experience movement difficulties that may be linked to processes involved in motor imagery (MI). This paper discusses recent advances in theory that underpin the use of MI training for children with DCD. This knowledge is translated in a new MI training protocol which is compared with the cognitive orientation to daily occupational performance (CO-OP). Children meeting DSM-5 criteria for DCD were assigned to MI (n = 4) or CO-OP (n = 4) interventions and completed nine treatment sessions, including homework exercises. Results were positive, with two children in the MI group and three in the CO-OP group improving their m-ABC-2 score by ≥ 2 standard scores, interpreted as a clinically meaningful change. Moreover, all children and parents noticed improvements in motor skills after training. This is the first study to demonstrate the feasibility of a theoretically principled treatment protocol for MI training in children with DCD, and extends earlier work.

Trial registration: The complete trial is registered at the Dutch trial register, www.trialregister.nl (NTR5471). http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=5471

Tactile localization performance in children with developmental coordination disorder (DCD) corresponds to their motor skill and not their cognitive ability

When localizing touches to the hands, typically developing children and adults show a "crossed hands effect" whereby identifying which hand received a tactile stimulus is less accurate when the hands are crossed than uncrossed. This demonstrates the use of an external frame of reference for locating touches to one's own body. Given that studies indicate that developmental vision plays a role in the emergence of external representations of touch, and reliance on vision for representing the body during action is atypical in developmental coordination disorder (DCD), we investigated external spatial representations of touch in children with DCD using the "crossed hands effect". Nineteen children with DCD aged 7-11years completed a tactile localization task in which posture (uncrossed, crossed) and view (hands seen, unseen) were varied systematically. Their performance was compared to that of 35 typically developing controls (19 of a similar age and cognitive ability, and 16 of a younger age but similar fine motor ability). Like controls, the DCD group exhibited a crossed hands effect, whilst their overall tactile localization performance was weaker than their peers of similar age and cognitive ability, but in line with younger controls of similar motor ability. For children with movement difficulties, these findings indicate tactile localization impairments in relation to age expectations, but apparently typical use of an external reference frame for localizing touch.

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 8-32years 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 was 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.

Developmental coordination disorder: core sensori-motor deficits, neurobiology and etiology

Among developmental disorders, DCD is one of the least studied and less understood one (Bishop, 2010). This review summarizes the current understanding of developmental coordination disorder in neuropsychology with a focus mainly on high level sensorimotor impairments, its etiology and its neural bases. We summarize these core deficits in the framework of an influent motor control model (Blakemore et al., 2002). DCD has several environmental risk factors which probably interplay with genetic factors but those have not been sufficiently identified. High-level sensori-motor deficits are probably multifactorial in DCD and involve predictive coding deficits as well as weaknesses in perceptual and sensory integration. At the brain level, DCD is associated with impaired structure and functions within the motor network. Throughout the review we highlight exciting new findings as well as potential future lines of research to provide a more comprehensive understanding of this disorder.

How do i fit through that gap? Navigation through apertures in adults with and without developmental coordination disorder

During everyday life we move around busy environments and encounter a range of obstacles, such as a narrow aperture forcing us to rotate our shoulders in order to pass through. In typically developing individuals the decision to rotate the shoulders is body scaled and this movement adaptation is temporally and spatially tailored to the size of the aperture. This is done effortlessly although it actually involves many complex skills. For individuals with Developmental Coordination Disorder (DCD) moving in a busy environment and negotiating obstacles presents a real challenge which can negatively impact on safety and participation in motor activities in everyday life. However, we have a limited understanding of the nature of the difficulties encountered. Therefore, this current study considered how adults with DCD make action judgements and movement adaptations while navigating apertures. Fifteen adults with DCD and 15 typically developing (TD) controls passed through a series of aperture sizes which were scaled to body size (0.9-2.1 times shoulder width). Spatial and temporal characteristics of movement were collected over the approach phase and while crossing the aperture. The decision to rotate the shoulders was not scaled in the same way for the two groups, with the adults with DCD showing a greater propensity to turn for larger apertures compared to the TD adults when body size alone was accounted for. However, when accounting for degree of lateral trunk movement and variability on the approach, we no longer saw differences between the two groups. In terms of the movement adaptations, the adults with DCD approached an aperture differently when a shoulder rotation was required and then adapted their movement sooner compared to their typical peers. These results point towards an adaptive strategy in adults with DCD which allows them to account for their movement difficulties and avoid collision.

Short-term motor learning of dynamic balance control in children with probable Developmental Coordination Disorder

PURPOSE

To explore the differences in learning a dynamic balance task between children with and without probable Developmental Coordination Disorder (p-DCD) from different cultural backgrounds.

PARTICIPANTS

Twenty-eight Dutch children with DCD (p-DCD-NL), a similar group of 17 South African children (p-DCD-SA) and 21 Dutch typically developing children (TD-NL) participated in the study.

METHODS

All children performed the Wii Fit protocol. The slope of the learning curve was used to estimate motor learning for each group. The protocol was repeated after six weeks. Level of motor skill was assessed with the Movement ABC-2.

RESULTS

No significant difference in motor learning rate was found between p-DCD-NL and p-DCD-SA, but the learning rate of children with p-DCD was slower than the learning rate of TD children. Speed-accuracy trade off, as a way to improve performance by slowing down in the beginning was only seen in the TD children, indicating that TD children and p-DCD children used different strategies. Retention of the level of learned control of the game after six weeks was found in all three groups after six weeks. The learning slope was associated with the level of balance skill for all children. This study provides evidence that children with p-DCD have limitations in motor learning on a complex balance task. In addition, the data do not support the contention that learning in DCD differs depending on cultural background.

Ophthalmic abnormalities in children with developmental coordination disorder

AIM

To explore associations between developmental coordination disorder (DCD) and ophthalmic abnormalities in children aged 7 to 8 years.

METHOD

Cross-sectional analysis of data from the Avon Longitudinal Study of Parents and Children (ALSPAC), a UK birth cohort, was performed. DCD was defined according to DSM-IV criteria. Children with neurological difficulties or IQ less than 70 were excluded. Ophthalmic abnormalities including visual acuity, refraction, and binocular function were assessed using standard tests. Children who achieved less than the 5th centile in the ALSPAC coordination test and either failed the National Curriculum handwriting test, or achieved less than the 10th centile in the Activities of Daily Living scale (ADL) were defined as having severe DCD, while those who scored between the 5th and 15th centiles in the coordination test and either failed the handwriting test, or achieved less than the 15th centile in the ADL were defined as having moderate DCD.

RESULTS

Complete data were available for 7154 children. One hundred and twenty children (1.8%) met the criteria for severe DCD. A further 215 children had moderate DCD. Children with severe DCD were more likely to have the following: abnormal sensory fusion at near (odds ratio [95% confidence interval]) (1.98 [1.13-3.48]) and distance (2.59 [1.16-5.79]) and motor fusion (1.74 [1.07-2.84]); reduced stereoacuity (2.75 [1.78-4.23]); hypermetropia (2.29 [1.1-4.57]) and anisometropia (2.27 [1.13-4.60]). The majority of children found to have both DCD and a refractive error, had been previously prescribed glasses and wore them for the assessments (71%).

INTERPRETATION

Children with severe DCD had abnormalities in binocular vision, refractive error, and ocular alignment. We recommend that children with DCD be assessed for ocular abnormalities as early intervention may improve long-term visual outcome. The impact of untreated ocular abnormalities such as refractive error on the accuracy of the diagnosis of DCD is difficult to ascertain and further work would be of benefit.

A comparison of running kinematics and kinetics in children with and without developmental coordination disorder

The aim of this study was to compare running gait in children with and without developmental coordination disorder (DCD). Fourteen boys with DCD (9.5 ± 1 yr) and 14 typically developing (TD) controls (9.6 ± 1 yr) ran at a velocity of 2.44 ± 0.25 m/s along a 15m track, with kinematic and kinetic data of the trunk and lower limb obtained for three cycles of each limb using a 12-camera Vicon MX system and AMTI force plate. Although features of the kinematic and kinetic trajectories were similar between groups, the DCD group displayed decreased peak knee extension compared with the TD group prior to initial foot contact (p = 0.016). Furthermore, the DCD group displayed increased variability in sagittal plane kinematics at the hip and ankle during toe off compared with the TD group. Kinetic analysis revealed that children with DCD displayed significantly reduced knee extensor moments during the stance phase of the running cycle (p = 0.033). Consequently, peak knee power absorption and ankle power generation was significantly lower in the DCD group (p = 0.041; p = 0.017). Furthermore, there was a trend for children with DCD to have shorter strides (p = 0.052, ES = 0.499) and a longer stance period than the TD controls (p=0.06, ES = 0.729). These differences may have implications for the economy of running and subsequently the planning of targeted intervention programs to improve running gait in children with DCD.

The role of vision in obese and normal-weight children's gait control

Previous research has suggested that perceptual-motor difficulties may account for obese children's lower motor competence; however, specific evidence is currently lacking. Therefore, this study examined the effect of altered visual conditions on spatiotemporal and kinematic gait parameters in obese versus normal-weight children. Thirty-two obese and normal-weight children (11.2±1.5 years) walked barefoot on an instrumented walkway at constant self-selected speed during LIGHT and DARK conditions. Three-dimensional motion analysis was performed to calculate spatiotemporal parameters, as well as sagittal trunk segment and lower extremity joint angles at heel-strike and toe-off. Self-selected speed did not significantly differ between groups. In the DARK condition, all participants walked at a significantly slower speed, decreased stride length, and increased stride width. Without normal vision, obese children had a more pronounced increase in relative double support time compared to the normal-weight group, resulting in a significantly greater percentage of the gait cycle spent in stance. Walking in the DARK, both groups showed greater forward tilt of the trunk and restricted hip movement. All participants had increased knee flexion at heel-strike, as well as decreased knee extension and ankle plantarflexion at toe-off in the DARK condition. The removal of normal vision affected obese children's temporal gait pattern to a larger extent than that of normal-weight peers. Results suggest an increased dependency on vision in obese children to control locomotion. Next to the mechanical problem of moving excess mass, a different coupling between perception and action appears to be governing obese children's motor coordination and control.

Brain activation of children with developmental coordination disorder is different than peers

OBJECTIVES

Children with developmental coordination disorder (DCD) struggle to learn new motor skills, demonstrating more variable performance than typically developing (TD) children. The purpose of this study was to determine whether patterns of brain activity differed between children with and without DCD while performing a motor task.

METHODS

Using functional MRI, we measured brain activation patterns in 7 children with DCD and 7 age-matched peers (aged 8-12 years) during a fine-motor, trail-tracing task.

RESULTS

Despite similar levels of behavioral motor performance, different patterns of brain activity were noted between the 2 groups. The group with DCD showed significantly more activation than control subjects in left inferior parietal lobule, right middle frontal gyrus, right supramarginal gyrus, right lingual gyrus, right parahippocampal gyrus, right posterior cingulate gyrus, right precentral gyrus, right superior temporal gyrus, and right cerebellar lobule VI. These results suggest that the group with DCD relied on visuospatial processing to complete the task. The TD group demonstrated significantly more activation than the group with DCD in left precuneus, left superior frontal gyrus, right superior temporal gyrus/insula, left inferior frontal gyrus, and left postcentral gyrus; these regions have been associated with spatial processing, motor control and learning, and error processing.

CONCLUSIONS

Children with DCD activate different brain regions from typical children when performing the same trail-tracing task. Despite the small sample size, our results contribute to a growing body of literature suggesting that children with DCD exhibit differences in neural networks and patterns of brain activation relative to same-age peers.

Balance problems during obstacle crossing in children with Developmental Coordination Disorder

The present study investigated the visuomotor and balance limitations during obstacle crossing in typically developing (TD) children and those with Developmental Coordination Disorder (DCD) (7-9 years old; N=12 per group). Spatiotemporal gait parameters as well as range and velocity of the centre of mass (COM) were determined in three conditions: overground walking at a self-selected speed, crossing a low obstacle and crossing a high obstacle (5% or 30% of the leg length, respectively). Both groups walked more slowly during obstacle crossing than walking over level ground. In addition, both groups exhibited a significant decrease in the spatial variability of their foot placements as they approached the obstacle, which was then negotiated with a similar strategy. There were no differences in approach distance, length of lead and trail step, or lead and trail foot elevation. Compared to walking over level ground, obstacle crossing led to a longer swing phase of the lead and trail foot and increased maximal medio-lateral COM velocity. In children with DCD, however, medio-lateral COM velocity was higher and accompanied by significantly greater medio-lateral COM amplitude. In conclusion, the results indicate that while TD-children and those with DCD exhibit satisfactory anticipatory control and adequate visual guidance, the latter group have a reduced ability to control the momentum of the COM when crossing obstacles that impose increased balance demands.

Effects of visual deprivation on intra-limb coordination during walking in children and adults

Following the laws of planar covariation, intersegmental coordination is defined with respect to the vertical and heading direction. This vertical reference can be estimated using multisensory information, amongst others visual cues play a role. In the past it was already shown that visual deprivation and/or perturbation of visual information largely affect gait kinematics. The goal of this study is to investigate the impact of visual deprivation on intra-limb movement coordination. Children aged between 3 and 11 years and young adults are included in this study to investigate age-related differences in the visual control of locomotion. Intersegmental coordination was tested under two different conditions: full vision (FV) and no vision (NV). Heading direction and walking speed were taken into account. A significant interaction effect was observed between visual condition and age for walking speed. Between age groups, no differences are observed in the FV condition but in the NV condition children walk significantly slower than adults. This shows that the relative importance of visual information is age dependent. Between age groups significant differences were found in heading direction. Coordination was characterized using the planar covariation technique, by constructing thigh versus shank and shank versus foot angle-angle plots and by cross-correlation function analysis. Regardless of the presence or absence of visual information, the planarity index remains high, indicating that the laws of planar covariation hold in the absence of visual afferent information. On the other hand, the shape of the gait loop does show significant differences between FV and NV conditions. Changes in the shape of the gait loop are primarily determined by changes in the coupling between the thigh and shank elevation angles. The coupling between the shank and foot elevation angles is dependent upon walking speed and does not differ between FV and NV conditions. Between age groups significant differences are observed in covariation plane orientation.

Visual deprivation leads to gait adaptations that are age- and context-specific: I. Step-time parameters

In children, visual information is crucial for static postural control, although age-related differences exist in the impact of visual perturbation on postural sway. Since static postural control and locomotion are closely related, we expect age-related differences in the impact of visual deprivation on dynamic stability and gait. It is hypothesised that this is related to the important role of vision in postural control. Postural stability and gait was tested in 20 adults and 40 children (3-11 years old) under two different visual conditions: eyes open (EO) and eyes closed (EC). Significant differences were found between EO and EC for postural sway, dimensionless walking speed, dimensionless stride length and duration of double support. Thus, we can state that visual deprivation affects locomotion both in adults and children. Concerning walking speed a significant interaction effect was observed with age. The difference in walking speed between EO and EC is larger in children than in adults. Furthermore, we found significant correlations between postural sway and walking speed, step frequency and stride length. These observations support the hypothesis that gait adaptations in situations of visual deprivation are related to balance problems.

The effects of a motor and a cognitive concurrent task on walking in children with developmental coordination disorder

The effects of type (cognitive vs. motor) and difficulty level (easy vs. hard) of a concurrent task on walking were examined in 10 boys and 4 girls (age 4-6 years) with developmental coordination disorder (DCD) and 28 age- and gender-matched unaffected children. Each child performed free walking (single task), walking while carrying an empty tray (dual task, the concurrent task being motor and easy), walking while carrying a tray with 7 marbles (the concurrent task being motor and hard), walking while repeating a series of digits forward (the concurrent task being cognitive and easy), and walking while repeating the digits backward (the concurrent task being cognitive and hard). Walking was affected by the concurrent task (i.e., dual-task cost) in the children with DCD more so than in the comparison children. Greater task difficulty also increased the dual-task cost in the children with DCD more so than in the comparison children. These patterns were only noted for the motor concurrent task. The cognitive concurrent task also affected walking, but the dual-task costs did not differ between difficulty levels, nor between the groups.