Slowed muscle force production and sensory organization deficits contribute to altered postural control strategies in children with developmental coordination disorder

Anticipatory postural adjustment deficits in children with developmental coordination disorder during a self-induced prehension task while standing on one leg

Effective postural control is essential for motor skill development, yet the specific nature of anticipatory control in children with Developmental Coordination Disorder (DCD) remains poorly understood for complex or dynamic stability tasks. This study investigated anticipatory postural adjustments (APA) during a self-initiated dynamic stability task. The Can Placement Task (CPT)-a self-initiated dynamic stability task-was performed by 23 children with DCD and 30 typically developing (TD) children aged 9-12 years. The task involved standing on one leg while also repositioning a can on the floor. Center of pressure (COP) movement was recorded by two force platforms during the five phases of the movement. The ground reaction force measured external support during both descent to pick up the can and ascent after replacing the can. The study used a mixed-design approach with group (DCD, TD) as a between-subject factor and condition (can position close or far) and phase of movement as within-subject. Distinct movement control characteristics were shown for children with DCD including a greater range of COP movement and higher COP velocity in the anterior-posterior direction prior to movement initiation compared with TD. The DCD group also relied more on external support during both the downward and upward phases of the CPT and needed more trials to complete the task. Only two significant interaction effects involving Group and the within-subject factors emerged. Children with DCD swayed significantly more at specific phases of the task, especially when coming up and restoring balance, and did not adapt COP velocity as a function of reaching distance. Dynamic control of posture in children with DCD is impaired as they struggle to generate the effective APAs necessary to maintain dynamic stability which leads to greater reliance on external support and more corrective movements. The CPT provides a valuable assessment of posture and dynamic balance control during a complex prehension movement performed on one leg; the task highlights distinct movement patterns between children with and without DCD.

Children with developmental coordination disorder have less variable motor unit firing rate characteristics across contractions compared to typically developing children

Introduction

Understanding the nuances of neuromuscular control is crucial in unravelling the complexities of developmental coordination disorder (DCD), which has been associated with differences in skeletal muscle activity, implying that children with DCD employ distinct strategies for muscle control. However, force generation and control are dependent on both recruitment of motor units and their firing rates and these fine details of motor function have yet to be studied in DCD. The purpose of this study was therefore to compare motor unit characteristics in a small muscle of the hand during low level, handgrip contractions in typically developing (TD) children and children with DCD.

Methods

Eighteen children (9 TD vs. 9 DCD) completed a series of manual handgrip contractions at 10 ± 5% of their maximum voluntary contraction. High density surface electromyography was used to record excitation of the first dorsal interosseus muscle. Recorded signals were subsequently decomposed into individual motor unit action potential trains. Motor unit characteristics (firing rate, inter-pulse interval, and action potential amplitude) were analysed for contractions that had a coefficient variation of <10%.

Results and Discussion

This study found few differences in average motor unit characteristics (number of motor units: TD 20.24 ± 9.73, DCD 27.32 ± 14.00; firing rate: TD 7.74 ± 2.16 p.p.s., DCD 7.86 ± 2.39 p.p.s.; inter-pulse interval: TD 199.72 ± 84.24 ms, DCD 207.12 ± 103 ms) when force steadiness was controlled for, despite the DCD group being significantly older (10.89 ± 0.78 years) than the TD group (9.44 ± 1.67 years). However, differences were found in the variability of motor unit firing statistics, with the children with DCD surprisingly showing less variability across contractions (standard deviation of coefficient of variation of inter-pulse interval: TD 0.38 ± 0.12, DCD 0.28 ± 0.11). This may suggest a more fixed strategy to stabilise force between contractions used by children with DCD. However, as variability of motor unit firing has not been considered in previous studies of children further work is required to better understand the role of variability in motor unit firing during manual grasping tasks, in all children.

Contributing factors to postural stability in Prader-Willi syndrome

BACKGROUND

Prader-Willi Syndrome (PWS) is a rare neurodevelopmental disorder affecting multiple functional parameters. This study examined postural stability and associated gait and neuromuscular factors in young adults with PWS.

METHODS

Participants included 10 adults with PWS [7 M/3F; Body Fat % 40.61 ± 7.79]; ten normal weight (NW) adults [7 M/3F; Body Fat % 23.42 ± 7.0]; ten obese (OB) adults [7 M/3F; Body Fat % 42.40 ± 5.62]. Participants completed the Sensory Organization Test (SOT)®. Condition (C) specific and a composite equilibrium score (CES) were calculated (maximum = 100). Quadriceps strength was assessed using an isokinetic dynamometer. Three-dimensional gait analyses were completed along a 10 m walkway using a motion capture system and two force plates. A gait stability ratio (GSR) was computed from gait speed and step length (steps/m).

RESULTS

The PWS group had lower scores for C1, C3, C4 and CES compared to the NW (p < .039 for all) and lower scores for C4 and CES than the OB (p < .019 for both) groups, respectively. In C5 (eyes closed, sway-referenced support) and C6 (sway-referenced vision and support), 33.3% of participants with PWS fell during the first trial in both conditions (X2 [2] 7.436, p = .024) and (X2 [2] 7.436, p = .024) but no participant in the other groups fell. Those with PWS showed higher GSR than participants with NW (p = .005) and those with obesity (p = .045).

CONCLUSION

Individuals with PWS had more difficulty maintaining standing balance when relying on information from the somatosensory (C3), visual-vestibular (C4) and vestibular systems (C5, C6). A more stable walk was related to shorter steps, slower velocity and reduced peak quadriceps torque. Participation in multisensory activities that require appropriate prioritization of sensory system(s) input for controlling balance in altered sensory environments should be routinely included. In addition, exercises targeting muscular force and power should be included as part of exercise programming in PWS.

Tai chi-muscle power training for children with developmental coordination disorder: a randomized controlled trial

This study compared the effectiveness of tai chi (TC) muscle power training (MPT), TC alone, MPT alone, and no training for improving the limits of stability (LOS) and motor and leg muscular performance and decreasing falls in children with developmental coordination disorder (DCD). One hundred and twenty-one children with DCD were randomly assigned to the TC-MPT, TC, MPT, or control group. The three intervention groups received TC-MPT, TC, or MPT three times per week for 3 months. Measurements were taken before and after the intervention period. The primary outcomes were the LOS completion time and dynamic LOS scores. The secondary outcomes included the Movement Assessment Battery for Children-Second Edition total test score and percentile rank, knee muscle peak force and time to peak force, and the number of falls. None of the interventions affected the LOS test scores. Improvements in the peak forces of the knee extensors and flexors were demonstrated in the TC (p = 0.006) and MPT groups (p = 0.032), respectively. The number of falls also decreased in these two groups (p < 0.001). Thus, clinicians may prescribe TC or MPT for children with DCD to increase their knee muscle strength and reduce their risk of falls.

Bibliometric analysis study on cognitive function in developmental coordination disorder from 2010 to 2022

Objective

To identify the research hotspots on cognitive function in developmental coordination disorder (DCD) in recent years, predict the research frontier and development trend, and provide more perspectives for the study of the DCD population.

Methods

Using CiteSpace and VOSviewer software to draw charts, 1,082 pieces of literature about DCD and cognitive function in the Web of Science core collection database from 2010 to 2022 were visually analyzed.

Results and conclusion

Interest in the cognitive function of DCD has been on the rise in the past 10 years. Over 40 countries and regions, 117 institutions and 200 researchers have participated in the corresponding research, mainly in the United States, and their institutions have published more highly influential results. The hot keywords are DCD, children, attention, working memory, performance, and attention-deficit/hyperactivity disorder (ADHD), and the main research hot topics include functional performance, population, cognitive psychology. The research directions include "DCD," "Asperger syndrome," "memory," "infant," "clumsiness," "neurodevelopmental disorder," "occupational therapy," "preschool children," "motor competence," "model," and "online control." Future research should focus on motor imagery and intrinsic models and use more neurophysiological techniques to reveal the cognitive characteristics of children with DCD and develop intervention programs.

Autistic Children Use Less Efficient Goal-Directed Whole Body Movements Compared to Neurotypical Development

Autistic children have differences in their movements which impact their functional performance. Virtual-reality enables researchers to study movement in safe, engaging environments. We used motion-capture to measure how 7-13-year-old autistic and neurotypical children make whole-body movements in a virtual-reality task. Although children in both groups were successful, we observed differences in their movements. Autistic children were less efficient moving to the target. Autistic children did not appear to use a movement strategy. While neurotypical children were more likely to overshoot near targets and undershoot far targets, autistic children did not modulate their strategy. Using kinematic data from tasks in virtual-reality, we can begin to understand the pattern of movement challenges experienced by autistic children.

Gut-Brain Axis Exploration: Stabilometric Platform Performances in Children Affected by Functional Gastrointestinal Disorders

OBJECTIVE

The pathophysiology of functional gastrointestinal disorders (FGIDs) is associated with dysfunction at various levels of the gut-brain axis. Hypervigilance can result in an increased tendency to report pain. In the present study, we aimed to explore whether hypervigilance can influence attentional processing in postural control in children with FGIDs.

PATIENTS AND METHODS

Fifty-nine participants classified into healthy subjects, those with FGIDs, and those with organic diseases (Org) based on Rome IV criteria were enrolled. Postural control under 6 sensory conditions was evaluated using a stabilometric platform. The mean velocity of the center of pressure (CoP) displacement in the anteroposterior direction and the mediolateral direction, the length of the CoP trajectory, and the sway area were also measured.

RESULTS

With visual and somatosensorial normal inputs, participants with FGIDs showed a higher number of anteroposterior (FGIDs: 4[interquartile range [IQR] 3-7], control [Cntl] 3 [IQR 3-4], P  < 0.05) latero-lateral oscillations (FGIDs: 3 [IQR 3-6], Cntl 3 [IQR 2-3], P  < 0.05) and a higher perimeter value (FGIDs: 148 [IQR 121-240], Cntl 124 [IQR 111-140], P  = 0.056) compared to healthy subjects. With normal visual but altered somatosensorial input, subjects with FGIDs showed higher values of all parameters (anteroposterior: FGIDs 6[IQR 5-8], Cntl and Org 5 [IQR 4-6], P  < 0.05; latero-lateral FGIDs 6 [IQR 4-8], Cntl 4 [IQR 4-5], Org 4[IQR 3-5], P  < 0.05; perimeter FGIDs 253 [IQR 167-305], Cntl 185 [IQR 161-217], Org 176 [IQR 142-219], P  < 0.05; area FGIDs 98 [IQR 81-233], Cntl 86 [IQR 59-114], Org 56 [IQR 41-97], P < 0.05).

CONCLUSIONS

The higher number of oscillations in subjects with FGIDs who had normal visual input could be expression of alteration in attention and therefore hypervigilance as hypothesized in the context of gut-brain axis alterations.

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.

Physical Therapy Management of Children With Developmental Coordination Disorder: An Evidence-Based Clinical Practice Guideline From the Academy of Pediatric Physical Therapy of the American Physical Therapy Association

BACKGROUND

Developmental coordination disorder (DCD), classified as a neurodevelopmental disorder in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), affects approximately 5% to 6% of school-aged children. Characteristics of DCD include poor motor coordination and delayed development of motor skills, not explained by other conditions. Motor deficits negatively affect school productivity, performance in activities of daily living, and recreation participation. Children with coordination problems, at risk for or diagnosed with DCD, should be evaluated by a team of professionals, including a physical therapist (PT).

PURPOSE

This clinical practice guideline (CPG) provides management strategies for PTs and informs clinicians and families about DCD. It links 13 action statements with specific levels of evidence through critical appraisal of the literature and provides recommendations for implementation.

RESULTS/CONCLUSIONS

The DCD CPG addresses examination, referral, first choice and supplemental interventions, discharge, compliance audits, implementation, and research recommendations. Supplemental tools are provided to support PT management.

The Prevalence of Left-Handedness Is Higher Among Individuals With Developmental Coordination Disorder Than in the General Population

Many medical, psychiatric and neurological conditions have been characterized by a high prevalence of left-handedness or mixed-handedness. Several studies have indicated an elevated frequency of left-handedness in children with Developmental Coordination Disorder (DCD). However, there have been few studies explicitly exploring this relationship. The assumption is that the prevalence of left-handedness in individuals with DCD is higher compared with the prevalence in the general population and resembles the prevalence described in children with other developmental disorders. Computerized searches were conducted in PubMed, PsycInfo and CINAHL databases. Thirty-eight studies were identified and included in the present review, containing handedness distributions across 1071 persons with DCD and 1,045 controls. The distribution of DCD participants across handedness-categories was proved to be significantly different from that of the control group, with 14.7 and 8.1% left-handers, respectively. The prevalence of left-handedness within the DCD-group is lower than that reported for ASD, and larger than in dyslexia. The elevated levels of left-handedness within the different developmental disorders supports the notion of an association between the different diagnoses. However, the present results are not sufficient to conclude anything about a common cause or underlying factor via the male hormone testosterone. The present results could act as a starting point for testing the hypothesis of such a common factor, as one of the requirements is an elevated prevalence of left-handedness, and without such considerable doubt would be cast upon the hypothesis.

Considerations for Testing and Treating Children with Central Vestibular Impairments

This perspective explores common pediatric diagnoses that could present with central vestibular pathway dysfunction, leading to delays in motor development and postural control, and gaze instability. Specifically, the following diagnoses are considered: cerebral palsy, myelomeningocele, vestibular migraine, attention-deficit hyperactivity disorder, developmental coordination disorder, concussion, childhood cancer, congenital muscular torticollis, adolescent idiopathic scoliosis, and autism. Suggestions for clinical screening, vestibular function testing, and vestibular rehabilitation for children with these diagnoses are based on evidence for the efficacy of testing and interventions for children with peripheral vestibular hypofunction. More research is needed to explore peripheral and central vestibular function in children with these diagnoses. Testing and intervention methods may need to be modified to accommodate for the specific behavior and motor challenges that some children might present. Researchers should develop technology so that gaze stabilization exercises can be delivered in a fun, functional, and effective way.

Adapted Taekwondo Training for Prepubertal Children with Developmental Coordination Disorder: A Randomized, Controlled Trial

This study evaluated the effectiveness of adapted Taekwondo (TKD) training on skeletal development and motor performance in children with developmental coordination disorder (DCD). One hundred forty-five prepubertal children with DCD were allocated to either the TKD or control groups. Children in the TKD group participated in a weekly 1-hour adapted TKD intervention and daily TKD home exercises for 12 weeks. The primary outcome (delay in skeletal development) and secondary outcomes (Movement Assessment Battery for Children (MABC) total impairment score, eye-hand coordination (EHC) scores, and a standing balance score) were measured at baseline, after the intervention and 3 months after the intervention. Skeletal development improved in both groups over time (p < 0.017). The TKD group had a significant delay in skeletal development at baseline compared to the control group (p = 0.003) but caught up with the controls at 3 months (p = 0.041). Improvements in the MABC scores were also seen in both groups across time (p < 0.017). Only the TKD group had a significant improvement in the EHC movement time at 3 (p = 0.009) and 6 months (p = 0.016). The adapted TKD intervention may be effective in improving the skeletal development and EHC movement time of children with DCD. For motor performance, the effect of maturation might be more profound.

Reactive balance performance and neuromuscular and cognitive responses to unpredictable balance perturbations in children with developmental coordination disorder

Developmental coordination disorder (DCD) is a common motor disorder affecting balance performance. However, few studies have investigated reactive balance performance and the underlying mechanisms in children with DCD. This study aimed to compare the reactive balance performance, lower limb muscle reflex contraction latency and attention level in response to unpredictable balance perturbations between 100 typically developing children and 120 children with DCD (with and without comorbid autism spectrum disorder) aged 6-9 years. Reactive balance performance was evaluated using a motor control test (MCT) conducted on a computerized dynamic posturography machine. The lower limb postural muscle responses and attention level before, during and after a MCT were measured using surface electromyography and electroencephalography, respectively. The results revealed that relative to typically developing children, those with DCD had a significantly longer MCT latency score in the backward platform translation condition (p = 0.048) but a significantly shorter latency score in the forward platform translation condition (p = 0.024). The MCT composite latency scores and the corresponding lower limb muscle onset latencies were similar between the groups. Children with DCD also demonstrated a lower attention level during and after sudden backward (p = 0.042) and forward (p = 0.031) platform translations, compared to typically developing children. Children with DCD were less attentive in response to postural threats, and their balance responses were direction-specific. Balance training for children with DCD might require an additional emphasis on sudden posterior-to-anterior balance perturbations, as well as on problems with inattention.

Cognitive and neuroimaging findings in developmental coordination disorder: new insights from a systematic review of recent research

AIM

To better understand the neural and performance factors that may underlie developmental coordination disorder (DCD), and implications for a multi-component account.

METHOD

A systematic review of the experimental literature published between June 2011 and September 2016 was conducted using a modified PICOS (population, intervention, comparison, outcomes, and study type) framework. A total of 106 studies were included.

RESULTS

Behavioural data from 91 studies showed a broad cluster of deficits in the anticipatory control of movement, basic processes of motor learning, and cognitive control. Importantly, however, performance issues in DCD were often shown to be moderated by task type and difficulty. As well, we saw new evidence of compensatory processes and strategies in several studies. Neuroimaging data (15 studies, including electroencephalography) showed reduced cortical thickness in the right medial orbitofrontal cortex and altered brain activation patterns across functional networks involving prefrontal, parietal, and cerebellar regions in children with DCD than those in comparison groups. Data from diffusion-weighted magnetic resonance imaging suggested reduced white matter organization involving sensorimotor structures and altered structural connectivity across the whole brain network.

INTERPRETATION

Taken together, results support the hypothesis that children with DCD show differences in brain structure and function compared with typically developing children. Behaviourally, these differences may affect anticipatory planning and reduce automatization of movement skill, prompting greater reliance on slower feedback-based control and compensatory strategies. Implications for future research, theory development, and clinical practice are discussed.

Impaired postural control in children with developmental coordination disorder is related to less efficient central as well as peripheral control

BACKGROUND

Developmental coordination disorder (DCD) is a neurodevelopmental impairment that affects approximately 6% of children in primary school age. Children with DCD are characterized by impaired postural control. It has yet to be determined what effect peripheral and central neuromuscular control has on their balance control.

OBJECTIVE

The aim of this study was to investigate the underlying mechanisms to impaired postural control in children with DCD using the rambling-trembling decomposition of the center of pressure (CoP).

METHOD

Nine children with DCD (9.0±0.5years, 7 boys, 2 girls) and 10 age- and gender-matched typically developing children (TD) with normal motor proficiency (9.1±0.4years, 7 boys and 3 girls) performed 3×30s bipedal standing on a force plate in six sensory conditions following the sensory organization procedure. Sway length was measured and rambling-trembling decomposition of CoP was calculated in medio-lateral (ML) and anterior-posterior (AP) direction.

RESULTS

Both rambling and trembling were larger for the children with DCD in AP (p=0.031; p=0.050) and ML direction (p=0.025; p=0.007), respectively. ML rambling trajectories did not differ in any conditions with fixed support surface. In ML direction children with DCD had a lower relative contribution of rambling to total sway (p=0.013).

CONCLUSION

This study showed that impaired postural control in children with DCD is associated with less efficient supraspinal control represented by increased rambling, but also by reduced spinal feedback control or peripheral control manifested as increased trembling.

Cognitive-motor interference during fine and gross motor tasks in children with Developmental Coordination Disorder (DCD)

BACKGROUND

While typically developing children produce relatively automatized postural control processes, children with DCD seem to exhibit an automatization deficit. Dual tasks with various cognitive loads seem to be an effective way to assess the automatic deficit hypothesis.

AIMS

The aims of the study were: (1) to examine the effect of a concurrent cognitive task on fine and gross motor tasks in children with DCD, and (2) to determine whether the effect varied with different difficulty levels of the concurrent task.

METHODS AND PROCEDURES

We examined dual-task performance (Trail-Making-Test, Trail-Walking-Test) in 20 children with DCD and 39 typically developing children. Based on the idea of the Trail-Making-Test, participants walked along a fixed pathway, following a prescribed path, delineated by target markers of (1) increasing sequential numbers, and (2) increasing sequential numbers and letters. The motor and cognitive dual-task effects (DTE) were calculated for each task.

RESULTS

Regardless of the cognitive task, children with DCD performed equally well in fine and gross motor tasks, and were slower in the dual task conditions than under single task-conditions, compared with children without DCD. Increased cognitive task complexity resulted in slow trail walking as well as slower trail tracing. The motor interference for the gross motor tasks was least for the simplest conditions and greatest for the complex conditions and was more pronounced in children with DCD. Cognitive interference was low irrespective of the motor task.

CONCLUSIONS AND IMPLICATIONS

Children with DCD show a different approach to allocation of cognitive resources, and have difficulties making motor skills automatic. The latter notion is consistent with impaired cerebellar function and the "automatization deficit hypothesis", suggesting that any deficit in the automatization process will appear if conscious monitoring of the motor skill is made more difficult by integrating another task requiring attentional resources.

The impact of the neurodevelopmental traction technique on activation of lateral abdominal muscles in children aged 11-13 years

BACKGROUND

The aim of the study was to evaluate the activation of lateral abdominal muscles (LAM) in response to neurodevelopmental traction technique as assessed by ultrasounds as well as to compare the effects of different traction forces.

OBJECTIVE

An experiment with repeated measurements of the dependent variables was conducted. Thirty-seven children (22 girls) participated.

METHODS

Measurements of LAM thickness (indicating LAM activation) were performed bilaterally during traction of 5% body weight: 1) in neutral position, 2) in 20° posterior trunk inclination; during traction of 15% body weight: 3) in neutral position, 4) in 20° posterior trunk inclination. The ultrasound technology was employed.

RESULTS

When applying the lighter traction the superficial LAM (external and internal oblique muscles) showed significant changes. The mean thickness of both muscles during traction increased (both p < 0.001). The deepest transversus abdominis showed no response (p > 0.05). Stronger traction elicited smaller changes. External and internal oblique muscles showed significant increases (p < 0.001, p < 0.01, respectively). Transversus abdominis became less thick during stronger traction (p < 0.01).

CONCUSIONS

The neurodevelopmental traction technique elicits the changes in LAM thickness in children with typical development. The superficial LAM show more distinct responses than the profound LAM. Stronger traction induces smaller LAM thickness changes than lighter traction.

A Novel Balance Training Program for Children With Developmental Coordination Disorder: A Randomized Controlled Trial

This study aimed to compare the effectiveness of a specific functional movement-power training (FMPT) program, a functional movement training (FMT) program and no training in the improvement of balance strategies, and neuromuscular performance in children with developmental coordination disorder (DCD). It was a randomized, single-blinded, parallel group controlled trial.

METHODS

161 children with DCD (age: 6-10 years) were randomly assigned to the FMPT, FMT, or control groups. The 2 intervention groups received FMPT or FMT twice a week for 3 months. Measurements were taken before, after, and 3 months after the end of the intervention period. The primary outcomes were the composite score and strategy scores on the sensory organization test as measured by a computerized dynamic posturography machine. Secondary outcomes included the knee muscle peak force and the time taken to reach the peak force. The balance strategies adopted in sensory challenging environments of the FMPT participants showed greater improvement from baseline to posttest than those of the FMT participants (7.10 points; 95% confidence interval, 1.51-12.69; P = 0.008) and the control participants (7.59 points; 95% confidence interval, 1.81-13.38; P = 0.005). The FMPT participants also exhibited greater improvement from baseline to the posttest in the knee extensor peak force and time to peak force in the knee flexors. The FMPT program was more effective than the conventional FMT program in the enhancement of balance strategies and neuromuscular performance in children with DCD.

Determinants of sport-specific postural control strategy and balance performance of amateur rugby players

OBJECTIVES

Postural control strategy and balance performance of rugby players are important yet under-examined issues. This study aimed to examine the differences in balance strategy and balance performance between amateur rugby players and non-players, and to explore training- and injury-related factors that may affect rugby players' balance outcomes.

DESIGN

Cross-sectional and exploratory study.

METHODS

Forty-five amateur rugby players and 41 healthy active individuals participated in the study. Balance performance and balance strategies were assessed using the sensory organization test (SOT) of the Smart Equitest computerized dynamic posturography machine. Rugby training history and injury history were solicited from the participants.

RESULTS

The SOT strategy scores were 1.99-54.90% lower in the rugby group than in the control group (p<0.05), and the equilibrium scores were 1.06-14.29% lower in the rugby group than in the control group (p<0.05). After accounting for age, sex and body mass index, only length of rugby training (in years) was independently associated with the SOT condition 6 strategy score, explaining 15.7% of its variance (p=0.006). There was no association between SOT condition 6 strategy/equilibrium scores and injury history among the rugby players (p>0.05).

CONCLUSIONS

Amateur rugby players demonstrated inferior balance strategy and balance performance compared to their non-training counterparts. Their suboptimal balance strategy was associated with insufficient training experience but not with history of injury.

Task-Specific Balance Training Improves the Sensory Organisation of Balance Control in Children with Developmental Coordination Disorder: A Randomised Controlled Trial

Sensory organisation of balance control is compromised in children with developmental coordination disorder (DCD). A randomised controlled trial involving 88 children with DCD was conducted to evaluate the efficacy of a task-specific balance training (functional-movement training, FMT) programme in improving balance deficits in a DCD population. The DCD participants were randomly assigned to either a FMT group or a control group. The FMT group received two training sessions/ week for 3 months. Measurements of the participants' sensory organisation (somatosensory, vestibular and visual ratios), balance and motor proficiency (Movement Assessment Battery for Children, MABC scores) and center of pressure sway velocity (Unilateral Stance Test, UST scores) were taken at baseline, immediately after FMT and 3 months after FMT. The FMT group showed greater improvements than the controls in somatosensory ratio at 3 and 6 months (all P < 0.001), but the within-group changes were not significant (P > 0.05). The results of both the MABC and the UST also indicated that the balance performance of the FMT group was significantly better than that of the control group at 3 and 6 months (all P < 0.05). Task-specific balance training was found to marginally improve the somatosensory function and somewhat improve the balance performance of children with DCD.

Direction-specific impairment of stability limits and falls in children with developmental coordination disorder: Implications for rehabilitation

Limit of stability (LOS) is an important yet under-examined postural control ability in children with developmental coordination disorder (DCD). This study aimed to (1) compare the LOS and fall frequencies of children with and without DCD, and (2) explore the relationships between LOS parameters and falls in the DCD population. Thirty primary school-aged children with DCD and twenty age- and sex-matched typically-developing children participated in the study. Postural control ability, specifically LOS in standing, was evaluated using the LOS test. Reaction time, movement velocity, maximum excursion, end point excursion, and directional control were then calculated. Self-reported fall incidents in the previous week were also documented. Multivariate analysis of variance results revealed that children with DCD had shorter LOS maximum excursion in the backward direction compared to the control group (p=0.003). This was associated with a higher number of falls in daily life (rho=-0.556, p=0.001). No significant between-groups differences were found in other LOS-derived outcomes (p>0.05). Children with DCD had direction-specific postural control impairment, specifically, diminished LOS in the backward direction. This is related to their falls in daily life. Therefore, improving LOS should be factored into rehabilitation treatment for children with DCD.

Virtual Sensorimotor Balance Training for Children With Fetal Alcohol Spectrum Disorders: Feasibility Study

BACKGROUND

Diminished sensory adaptation has been associated with poor balance control for children with fetal alcohol spectrum disorders (FASD). A virtual reality system, Sensorimotor Training to Affect Balance, Engagement and Learning (STABEL), was developed to train sensory control for balance.

OBJECTIVES

The purpose of this study was to examine the STABEL system in children with FASD and children with typical development (TD) to (1) determine the feasibility of the STABEL system and (2) explore the immediate effects of the STABEL system on sensory attention and postural control.

DESIGN

This is a technical report with observational study data.

METHODS

Eleven children with FASD and 11 children with TD, aged 8 to 16 years, completed 30 minutes of STABEL training. The children answered questions about their experience using STABEL. Sensory attention and postural control were measured pre- and post-STABEL training with the Multimodal Balance Entrainment Response system and compared using repeated-measures analysis of variance.

RESULTS

All children engaged in game play and tolerated controlled sensory input during the STABEL protocol. Immediate effects post-STABEL training in both groups were increased postural sway velocity and some changes in entrainment gain. Children with FASD showed higher entrainment gain to vestibular stimuli. There were no significant changes in sensory attention fractions.

LIMITATIONS

The small sample size, dose of STABEL training, and exploratory statistical analyses are study limitations, but findings warrant larger systematic study to examine therapeutic effects.

CONCLUSIONS

Children completed the training protocol, demonstrating the feasibility of the STABEL system. Differences in postural sway velocity post-STABEL training may have been affected by fatigue, warranting further investigation. Limited immediate effects suggest more practice is needed to affect sensory attention; however, entrainment gain changes suggest the STABEL system provoked vestibular responses during balance practice.

Deficits in Lower Limb Muscle Reflex Contraction Latency and Peak Force Are Associated With Impairments in Postural Control and Gross Motor Skills of Children With Developmental Coordination Disorder: A Cross-Sectional Study

This cross-sectional, exploratory study aimed to compare neuromuscular performance, balance and motor skills proficiencies of typically developing children and those with developmental coordination disorder (DCD) and to determine associations of these neuromuscular factors with balance and motor skills performances in children with DCD.One hundred thirty children with DCD and 117 typically developing children participated in the study. Medial hamstring and gastrocnemius muscle activation onset latencies in response to an unexpected posterior-to-anterior trunk perturbation were assessed by electromyography and accelerometer. Hamstring and gastrocnemius muscle peak force and time to peak force were quantified by dynamometer, and balance and motor skills performances were evaluated with the Movement Assessment Battery for Children (MABC).Independent t tests revealed that children with DCD had longer hamstring and gastrocnemius muscle activation onset latencies (P < 0.001) and lower isometric peak forces (P < 0.001), but not times to peak forces (P > 0.025), than the controls. Multiple regression analysis accounting for basic demographics showed that gastrocnemius peak force was independently associated with the MABC balance subscore and ball skills subscore, accounting for 5.7% (P = 0.003) and 8.5% (P = 0.001) of the variance, respectively. Gastrocnemius muscle activation onset latency also explained 11.4% (P < 0.001) of the variance in the MABC ball skills subscore.Children with DCD had delayed leg muscle activation onset times and lower isometric peak forces. Gastrocnemius peak force was associated with balance and ball skills performances, whereas timing of gastrocnemius muscle activation was a determinant of ball skill performance in the DCD population.

Kinesthetic deficit in children with developmental coordination disorder

The aim of this study was to measure and compare kinesthetic sensitivity in children with developmental coordination disorder (DCD) and typically developing (TD) children between 6 and 11 years old. 30 children with DCD aged 6 to 11 years (5 in each age group) and 30 TD children participated in the study. Participants placed their forearms on a passive motion apparatus which extended the elbow joint at constant velocities between 0.15 and 1.35°s(-1). Participants were required to concentrate on detection of passive arm motion and press a trigger held in their left hand once they sensed it. The detection time was measured for each trial. The DCD group was significantly less sensitive in detection of passive motion than TD children. Further analysis of individual age groups revealed that kinesthetic sensitivity was worse in DCD than TD children for age groups beyond six years of age. Our findings suggested that individual with DCD lag behind their TD counterparts in kinesthetic sensitivity. Between the ages of 7 and 11 years the difference between groups is quantifiable and significant with 11 year old children with DCD performing similar to 7 year old TD children.

Twelve-month-old infants anticipatorily plan their actions according to expected object weight in a novel motor context

Planning actions in anticipation of object weight is fundamental to skilled action production. The present study investigated whether infants can apply weight information gained from direct actions on objects in order to plan their actions according to object weight in a novel and indirect motor context. In the present study, two groups of 12-month-old infants were provided with experience acting directly on two blocks of different weights and colors (70 versus 470 g; red versus yellow). Subsequently, infants were administered a novel task in which the same blocks (standard condition; n = 60), or blocks of the reversed color-weight pairings (switch condition; n = 60), were placed out-of-reach, on top of a cloth, and infants were encouraged to retrieve the block by acting on the cloth. Infants in the switch condition produced more failed cloth pulls when retrieving the 470 g block, due to inadequate generation of anticipatory force, relative to infants in the standard condition. This demonstrates that infants' force on the cloth was prospectively generated based on their mental representation of the supported block's weight, which was formed through their previous direct actions on the object. Thus, infants use information about the weight of an object in order to anticipate how to obtain that object in a novel and indirect problem-solving context.

Developmental coordination disorder and overweight and obesity in children: a systematic review

Children with developmental coordination disorder (DCD) find themselves less competent than typically developing children with regard to their physical abilities and often experience failure. They are therefore likely to avoid physical activity. Physical inactivity is considered an important risk factor for developing overweight and obesity. The aim of this study is to assess the association between DCD and overweight and obesity in children and whether this association is influenced by age and/or gender. Six electronic databases were systematically searched. Titles and abstracts were screened for relevance. Remaining studies were subjected to full paper review. The quality of the included articles was assessed and relevant data were extracted for comparison. The search yielded 273 results. Twenty-one studies, based on 10 cohorts, were included. Participants' ages ranged from 4 to 14 years. In all cohorts, children with DCD had higher body mass index scores, larger waist circumference and greater percentage body fat compared with controls. Seven studies assessed the effect of gender and four studies provided information on the effect of age. Children with DCD seem to be at greater risk for overweight and obesity. This risk may be higher for boys and seems to increase with age and with the severity of motor impairment.