Altered postural control strategies and sensory organization in children with developmental coordination disorder

Consequences of vestibular hypofunction in children with ADHD/DCD

BACKGROUND

Children with Attention Deficit Hyperactivity Disorder (ADHD) demonstrate a heterogeneous sensorimotor, emotional, and cognitive profile. Comorbid sensorimotor imbalance, anxiety, and spatial disorientation are particularly prevalent among their non-core symptoms. Studies in other populations presented these three comorbid dysfunctions in the context of vestibular hypofunction.

OBJECTIVE

To test whether there is a subgroup of children with ADHD who have vestibular hypofunction presenting with concomitant imbalance, anxiety, and spatial disorientation.

METHODS

Children with ADHD-only (n = 28), ADHD + Developmental Coordination Disorder (ADHD + DCD; n = 38), and Typical Development (TD; n = 19) were evaluated for vestibular function by the Dynamic Visual Acuity test (DVA-t), balance by the Bruininks-Oseretsky Test of motor proficiency (BOT-2), panic anxiety by the Screen for Child Anxiety Related Emotional Disorders questionnaire-Child version (SCARED-C), and spatial navigation by the Triangular Completion test (TC-t).

RESULTS

Children with ADHD vs. TD presented with a high rate of vestibular hypofunction (65 vs. 0 %), imbalance (42 vs. 0 %), panic anxiety (27 vs. 11 %), and spatial disorientation (30 vs. 5 %). Children with ADHD + DCD contributed more frequent and severe vestibular hypofunction and imbalance than children with ADHD-only (74 vs. 54 %; 58 vs. 21 %, respectively). A concomitant presence of imbalance, anxiety, and spatial disorientation was observed in 33 % of children with ADHD, all sharing vestibular hypofunction.

CONCLUSIONS

Vestibular hypofunction may be the common pathophysiology of imbalance, anxiety, and spatial disorientation in children. These comorbidities are preferentially present in children with ADHD + DCD rather than ADHD-only, thus likely related to DCD rather than to ADHD disorder. Children with this profile may benefit from a vestibular rehabilitation intervention.

Study protocol to examine the effects of acute exercise on motor learning and brain activity in children with developmental coordination disorder (ExLe-Brain-DCD)

INTRODUCTION

Developmental coordination disorder (DCD) is one of the most prevalent pediatric chronic conditions. Without proper intervention, significant delays in motor skill performance and learning may persist until adulthood. Moderate-to-vigorous physical exercise has been proven to improve motor learning (adaptation and consolidation) in children with or without disorders. However, the effect of a short bout of physical exercise on motor adaptation and consolidation in children with DCD has not been examined. Furthermore, the role of perceptual-motor integration and attention as mediators of learning has not been examined via neuroimaging in this population.

OBJECTIVES

Therefore, the primary aims of this project will be to compare children with and without DCD to (a) examine the effect of acute exercise on motor learning (adaptation and consolidation) while performing a rotational visuo-motor adaptation task (rVMA), and (b) explore cortical activation in the dorsolateral- and ventrolateral-prefrontal cortex areas while learning the rVMA task under rest or post-exercise conditions.

METHODS

One hundred twenty children will be recruited (60 DCD, 60 controls) and within-cohort randomly assigned to either exercise (13-minute shuttle run task) or rest prior to performing the rVMA task. Adaptation and consolidation will be evaluated via two error variables and three retention tests (1h, 24h and 7 days post adaptation). Cortical activation will be registered via functional near-infrared spectroscopy (fNIRS) during the baseline, adaptation, and consolidation.

DISCUSSION

We expect to find exercise benefits on motor learning and attention so that children with DCD profiles will be closer to those of children with typical development. The results of this project will provide further evidence to: (a) better characterize children with DCD for the design of educational materials, and (b) establish acute exercise as a potential intervention to improve motor learning and attention.

Short- and Long-Term Changes in Balance After Active Video Game Training in Children With and Without Developmental Coordination Disorder: A Randomized Controlled Trial

Active video games (AVG) have been used as training tools and are known to ameliorate balance performance in children with Developmental Coordination Disorder (DCD). Our aim was to evaluate balance using clinical tests and by measuring body sway using a force plate with a mixed design of vision (eyes open/eyes closed), surface (rigid/soft), and support (stance/semitandem) before, and after, training and 4 months later (follow-up). Thirty-six DCD children and 40 typically developing children participated in the study, of which 50 children (26 DCD; 24 typically developing) were retested after 4 months. Balance improved on the clinical measures after the training, which was independent of type of AVG (Wii-Fit and Xbox Kinect) used, and this effect was still present after 4 months. The AVG training did not influence general sway behavior, but only sway in the eyes-open condition, corresponding with task demands of the training and indicating a training-specific effect. Overall, DCD children and typically developing children responded comparably to the AVG training, thereby maintaining the gap in performance between the two groups. The changes in postural sway are interpreted as a sign of more confidence and less freezing of the joints, enabling greater flexibility of movements and balance strategies as supported by the improved performance on balance tests in the DCD children. This is the first study that showed long-term effects of AVG training on balance performance. However, these follow-up results should be interpreted with caution given that 35% of the children were lost in follow-up.

Motion sense sensitivity of the ankle is abnormal and correlated with motor performance in children with and without a probable developmental coordination disorder

This study systematically examined ankle motion sense sensitivity and its relation to motor functions in children with and without a probable developmental coordination disorder (pDCD). Seventy-two children aged 10-11 years were recruited, including thirty-six children with pDCD and 36 age- and sex-matched typically developing (TD) children. Children placed their dominant foot on a passive ankle motion apparatus that induced plantar flexion of the ankle under nine constant velocities ranging between 0.15 and 1.35°/s. The adjusted movement detection time (ADT) to passive ankle motion was obtained to measure ankle motion sense sensitivity. The results showed that, in comparison to that in the TD group, ankle ADT was significantly increased by 22-59% for the range of velocities in the pDCD group. A correlation analysis showed that mean ADTs were significantly correlated with the manual dexterity (r = -0.33, p = 0.005) and balance (r = -0.24, p = 0.046) scores on the Movement Assessment Battery for Children (MABC-2) in the combined group. Similar correlations were found between the ADTs and the manual dexterity (r = -0.37, p = 0.028) and total motor (r = -0.34, p = 0.047) scores in the TD group. This study documents that ankle motion sense sensitivity to passive foot motion is reduced and is likely to contribute to poor motor performance in children with and without pDCD.

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.

Atypical adaptive postural responses in children with developmental coordination disorder: Implications for rehabilitation

BACKGROUND

Adaptive postural control is an important yet underexamined area in children with developmental coordination disorder (DCD). This study compared adaptive postural responses between children with DCD and those with typical development.

METHODS

This was an exploratory cross-sectional study. Fifty-two children with DCD (aged 6-9 years) and 52 age- and sex-matched children with typical development participated in the study. Their adaptive postural (motor) responses were assessed using the Adaptation Test (ADT) on a computerized dynamic posturography machine. The sway energy score (SES) for each ADT trial and the average SES of five trials for both toes-up and toes-down platform inclination conditions were recorded.

RESULTS

The SESs were lower in the DCD group than in the control group in ADT toes-up trial 1 (p = 0.009) and on average (p = 0.044). In the control group, the SES decreased from trial 1 to trial 2 for both the ADT toes-up (p = 0.005) and toes-down conditions (p < 0.001).

SIGNIFICANCE

Adaptive postural responses were absent in children with DCD, and these children used less force (i.e., sway energy) to overcome postural instability. Therefore, both adaptive balance and neuromuscular training should be factored into rehabilitation programs for children with DCD.

The influence of vestibular system and fetal presentation on handedness, cognitive and motor development: A comparison between cephalic and breech presentation

Genetics are undoubtedly implicated in the ontogenesis of laterality. Nonetheless, environmental factors, such as the intrauterine environment, may also play a role in the development of functional and behavioral lateralization. The aim of this study was to test the Left-Otolithic Dominance Theory (LODT; Previc, 1991) by investigating a hypothetical developmental pattern where it is assumed that a breech presentation, which is putatively associated with a dysfunctional and weakly lateralized vestibular system, can lead to weak handedness and atypical development associated with language and motor difficulties. We used the ALSPAC cohort of children from 7 to 10 years of age to conduct our investigation. Our results failed to show an association between the vestibular system and fetal presentation, nor any influence of the latter on hand preference, hand performance, or language and motor development. Bayesian statistical analyses supported these findings. Contrary to our LODT-derived hypotheses, this study offers evidence that fetal presentation does not influence the vestibular system's lateralization and seems to be a poor indicator for handedness. Nonetheless, we found that another non-genetic factor, prematurity, could lead to atypical development of handedness. This article is protected by copyright. All rights reserved.

The influence between gestational age and postural control, a systematic review

The central nervous system (CNS) of preterm infants might have some peculiarities which distinguish it from that of full term infants. The difficulties associated with prematurity are the main cause of deaths all over the world during the new-born period after community-acquired pneumonia, and the second cause of deaths worldwide in children under five years old. Early recognition of signs indicating fragile postural control in premature infants can support understanding and help prevent and early intervention on possible future neuromotor dysfunctions in these subjects. The purpose of this paper is to determine if there is a qualitatively different development of postural control in premature infants without neurological involvement and infants born at term. We conducted a systematic review of longitudinal and cross-sectional case-control studies published between 2010 and March 2020 on this topic. The evaluation of parameters related to postural control was also included. The methodological quality of the selected works was evaluated using the CASPe critical reading programme for cases and controls. PRISMA guidelines for systematic reviews were followed for prematurity and postural control. 16 articles were included. The total sample amounted to 3,460 participants, of which 1,860 in the preterm group, and 1,600 in the control group. All the studies found show a poorer postural control by the group of children born preterm compared to the group of children born at term and one study indicating more limited postural control with higher prematurity. Regarding the methodological quality according to CASPe, those studies exceeding half of the total score were considered of adequate quality.

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.

Relationship Between Chronic Conditions and Balance Disorders in Outpatients with Dizziness: A Hospital-Based Cross-Sectional Study

Background

Balance dysfunction is common in adult outpatients with dizziness, especially those who are older, which can lead to catastrophic outcomes such as falls. The aim of this study was to investigate the association between chronic conditions and balance disorders in patients with dizziness, especially those who are elderly.

Material/Methods

A cross-sectional study was conducted in adult outpatients diagnosed with dizziness referred to the Department of Otolaryngology at Beijing Tongren Hospital from September 2017 to August 2018. All of the patients completed a self-administered, structured questionnaire. Demographic data and information on history of chronic conditions were collected and the patients were divided into 2 groups based on whether their balance was normal or abnormal.

Results

Three hundred and thirty-two patients were included in this study, 168 in the normal balance group and 164 in the abnormal balance group. The incidence of chronic conditions, including hypertension and diabetes, in the abnormal balance group was higher than that in the normal balance group (all P<0.05). In subgroup analysis based on age, in those who were aged ≥60 years, the prevalence of chronic diseases was higher in the abnormal balance group than in the normal balance group (P=0.002), while there was no difference in age between the groups with abnormal and normal balance. Hypertension (OR: 2.268; 95%CI: 1.038–4.957; P<0.05) was a risk factor for balance disorders in elderly patients rather than those who were younger (P>0.05).

Conclusions

Our results show that chronic conditions are associated with balance function in older patients with dizziness. Thus, specialists should consider chronic conditions, especially hypertension, in elderly patients with dizziness.

Postural Control in Childhood: Investigating the Neurodevelopmental Gradient Hypothesis

Neurodevelopmental disorders (NDDs) have been suggested to lie on a gradient continuum, all resulting from common brain disturbances, but with different degrees of impairment severity. This case-control study aimed to assess postural stability against such hypothesis in 104 children/adolescents aged 5–17, of whom 81 had NDDs and 23 were healthy controls. Compared to healthy controls, Autism Spectrum Disorder (ASD) resulted in the most severely impaired neurodevelopmental condition, followed by Attention Deficit Hyperactive Disorder (ADHD) and Tourette Syndrome (TS). In particular, while ASD children/adolescents performed worse than healthy controls in a number of sensory conditions across all parameters, ADHD children/adolescents performed worse than healthy controls only in the sway area for the most complex sensory conditions, when their vision and somatosensory functions were both compromised, and performance in Tourette Syndrome (TS) was roughly indistinguishable from that of healthy controls. Finally, differences were also observed between clinical groups, with ASD children/adolescents, and to a much lesser extent ADHD children/adolescents, performing worse than TS children/adolescents, especially when sensory systems were not operationally accurate. Evidence from this study indicates that poor postural control may be a useful biomarker for risk assessment during neurodevelopment, in line with predictions from the gradient hypothesis.

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.

Practitioner Review: Effective management of functional difficulties associated with sensory symptoms in children and adolescents

BACKGROUND

Sensory symptoms are defined as atypical behavioral responses to daily sensory stimuli that impact on the performance of everyday routines. Sensory symptoms have been observed in young people with and without developmental concerns. There is uncertainty, however, regarding the best way to identify and manage sensory symptoms. The aim of this paper is  to provide a review of current best evidence regarding measurement of and interventions for sensory symptoms.

METHODS

A narrative review methodology is adopted to address the aims of this paper. First, sensory symptoms are defined, and then, an overview of the evidence for the relationship between sensory symptoms and childhood function is provided. Second, commonly used sensory assessment tools are summarized and evaluated. Finally, an overview and critique of the evidence for sensory and nonsensory-based interventions addressing sensory symptoms are given.

RESULTS

The terminology used to describe sensory symptoms varies by discipline, and several conceptual taxonomies including sensory subtypes have been proposed. There is ample evidence to support the association of sensory symptoms with childhood function including social engagement, repetitive behaviors, anxiety, and participation in self-care routines. Measurement of sensory symptoms is dominated by proxy-report instruments, and few single instruments assess the entire domain of sensory symptomatology. The evidence for interventions for sensory symptoms is emerging but still limited by low quantity and methodological concerns.

CONCLUSIONS

Effective management of sensory symptoms may mitigate the burden of neurodevelopmental disability and mental illness in young people. Identification of sensory symptoms should be conducted by a skilled practitioner utilizing multiple measurement methods. Intervention protocols for sensory symptoms should be informed by current best evidence which is strongest for Ayres Sensory Integration^® , Qigong massage, the Alert Program^® , and Social Stories. To make significant progress in this field, however, new intervention studies must address the question of 'what intervention works for whom?'.

An Instrumented Assessment of a Rhythmic Finger Task among Children with Motor Coordination Difficulties

BACKGROUND

Coordination is crucial for motor function, yet objective clinical evaluations are limited. We therefore developed and tested the reliability and validity of a low-cost sensorized evaluation of a rhythmic finger task.

METHODS

Children with coordination difficulties (n = 24) and typically developing children (n = 24) aged from 5 to 7 years performed the Sensorized Finger Sequencing Test (SFST), a finger sequencing test that records the correct sequence, total time, and the standard deviation (SD) of touch time. Additionally, motor performance tests and parents' reports were applied in order to test the reliability and validity of the SFST.

RESULTS

The study group had significantly greater thumb-finger test scores-total time in the dominant hand (p = 0.035) and the SD of the touch time in both dominant (p = 0.036) and non-dominant (p = 0.032) hands. Motor performance tests were not correlated with the SFST. Test-retest reliability in 10 healthy children was found for the SD of touch time in the dominant hand (r = 0.87, p = 0.003).

CONCLUSIONS

The SFST was successful in assessing the movement pattern variability reported in children with motor difficulties. This exploratory study indicates that the low-cost SFST could be utilized as an objective measure for the assessment of proprioception components, which currently are overlooked by standardized motor performance assessments.

Early motor signs of attention-deficit hyperactivity disorder: a systematic review

ADHD is a common neurodevelopmental disorder with onset of symptoms typically in early childhood. First signs of the disorder, including language delay, motor delay and temperament characteristics, may be evident as early as infancy. The present review describes published evidence about early motor signs of either children with later symptoms of ADHD or a later diagnosis of the disorder. Nine published cohort studies were included after a systematic search of related terms in PubMed and PsycInfo databases. Study eligibility criteria included: (1) report on early motor function or any motor-related signs; (2) the presence of a participants' assessment by/at 12 months of age; (3) report of a later presence of ADHD symptoms. The limited number of reports included suggests an association between mild early neurological markers and later developmental coordination disorder and motor overflow movements. Unfortunately, due to their small sample sizes and focus on group reports rather than individuals, they have limited power to find strong associations. Early motor indicators of ADHD, if present, appear to be non-specific, and therefore not yet useful in clinical screening. Spontaneous motility seems to be a promising measure for early ADHD detection, although further studies with large cohorts are recommended to determine its clinical role in children at risk for ADHD.

Neuromuscular training for children with developmental coordination disorder: A randomized controlled trial

BACKGROUND

Adaptive balance control is often compromised in children with developmental coordination disorder (DCD). Neuromuscular training (NMT) is commonly used in clinical settings to improve neuromuscular control and hence balance performance in these children. However, its effectiveness has not been proven scientifically. This randomized controlled study aimed to explore the effectiveness of NMT for improving adaptive balance performance and the associated leg muscle activation times in children with DCD.

METHODS

Eighty-eight children with DCD were randomly assigned to the NMT or control group (44 per group). The NMT group received two 40-minute NMT sessions/week for 3 months, whereas the control group received no intervention. The outcomes were measured at baseline and 3 and 6 months. The primary outcome was the sway energy score (SES) in both the toes-up and toes-down conditions as derived using the Adaptation Test (ADT). Secondary outcomes included the medial gastrocnemius, medial hamstring, tibialis anterior and rectus femoris muscle activation onset latencies during ADT, measured using surface electromyography and accelerometry. Data were analyzed using a repeated measures analysis of covariance based on the intention-to-treat principle.

RESULTS

At 3 months, no significant within-group or between-group differences were noted in the SESs for either group. At 6 months, the toes-down SES decreased by 6.8% compared to the baseline value in exclusively the NMT group (P = .004). No significant time, group or group-by-time interaction effects were observed in any leg muscle activation outcomes.

CONCLUSIONS

Short-term NMT failed to improve adaptive balance performance and leg muscle activation times in children with DCD. Further studies should explore the clinical applications of longer-term task-specific interventions intended to improve the adaptive balance performance of these children.

Wearable-based electronics to objectively support diagnosis of motor impairments in school-aged children

Developmental coordination disorder (DCD) and attention-deficit hyperactivity disorder (ADHD) are neuro-developmental disorders, starting in childhood, which can affect the planning of movements and the coordination. We investigated how and in which measure a system based on wearable inertial measurement units (IMUs) can provide an objective support to the diagnosis of motor impairments in school-aged children. The IMUs measured linear and rotational movements of 37 schoolchildren, 7-10yo, 17 patients and 20 control subjects, during the execution of motor exercises, performed under medical and psychiatric supervision, to assess different aspects of the motor coordination. The measured motor parameters showed a high degree of significance in discriminating the ADHD/DCD patients from the healthy subjects, pointing out which motor tasks are worth focusing on. So, medical doctors have a novel key lecture to state a diagnosis, gaining in objectivity with respect to the standard procedures which mainly involve subjective human judgment. Differently to other works, we propose a novel approach in terms of number of used IMUs and of performed motor tasks. Moreover, we demonstrate the meaningful parameters to be considered as more discriminant in supporting the medical diagnosis.

Children with Autism Spectrum Disorder, Developmental Coordination Disorder, and typical development differ in characteristics of dynamic postural control: A preliminary study

BACKGROUND

Autism Spectrum Disorder (ASD) and Developmental Coordination Disorder (DCD) are developmental disorders with distinct definitions and symptoms. However, both conditions share difficulties with motor skills, including impairments in postural control. While studies have explored postural sway variables in children with DCD and ASD as compared to typical development (TD), few have used kinematic data to assess the magnitude of differences between these two neurodevelopmental conditions. There are few sensitive and specific measures available to assess balance impairment severity in these populations.

RESEARCH QUESTION

Do individuals with ASD, DCD, and TD differ in dynamic postural control?

METHODS

We quantified postural control differences between ASD, DCD, and TD during a dynamic balance task. 10 ASD, 10 DCD, and 8 TD agematched children completed a dynamic postural control task in a virtual environment. They leaned to shift their center of pressure (CoP) to match a user-controlled object to an oscillating target (0.1 Hz-0.8 Hz).

RESULTS

The DCD group had higher CoP accelerations compared to ASD or TD. While the DCD and TD groups did not differ in their medial-lateral velocity, the ASD group had low medial-lateral velocity and acceleration as compared to DCD and TD. ASD group velocity and acceleration did not differ from that of the TD group in the anterior-posterior direction. Higher accelerations in the DCD group reflected non-fluid movements; by contrast, the ASD group had slower, more fluid movements. Results may reflect differences in how children with ASD and DCD plan, execute, and modify motor actions.

SIGNIFICANCE

This study demonstrates the potential utility of CoP acceleration and velocity as a sensitive and specific means of differentiating between ASD, DCD, and TD. Results indicating group differences between ASD and DCD in velocity and acceleration profiles represent an important step toward understanding how these populations modify motor plans during dynamic tasks.

Persistent primary reflexes affect motor acts: Potential implications for autism spectrum disorder

In typical motor development progress in use of goal-directed actions and communicative gestures depends on the inhibition of several primitive reflexes, especially those that involve the hand or mouth. This study explored the relationship between the persistence of primitive reflexes that involve the hand or mouth and the motor repertoire in a sample of 12- to 17-month-old infants. Moreover, since children with Autism Spectrum Disorders (ASD) often have difficulty in performing skilled movements and show poor gesture repertoire, and since ASD represents the upper extreme of a constellation of traits that may be continuously distributed in the general population, we investigated the relationship between the persistence of primitive reflexes in the same sample of infants and the subclinical autistic traits measured in their parents. Results revealed that the persistence of the primitive reflexes correlated with motor repertoire irrespective of infant's age, and it was greater among infants whose parents had more subclinical autistic traits. Our findings suggest that the persistence of primitive reflexes might alter the developmental trajectory of future motor ability and therefore their evaluation might be an early indicator of atypical development.

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.

A Tailor-Made Exercise Program for Improving Balance and Mobility in Older Adults With Type 2 Diabetes

Effectiveness of an exercise program designed for improving postural control and mobility in older adults with type 2 diabetes was investigated. Ninety-three adults 65 or older diagnosed with type 2 diabetes and able to walk unaided were recruited. The intervention group received exercise training focused on ankle strengthening and mobility twice per week for 10 weeks. The control group did not participate in any exercise program. After 10 weeks, the intervention group showed significantly greater improvement in the mean Sensory Organization Test composite score (4.4 vs. 0.3; p = 0.01) as well as visual ratio (0.1 vs. 0.002; p = 0.01) and vestibular ratio (0.1 vs. 0.003; p < 0.001) than the control group after adjusting for covariates. A greater trend of improvement in the Timed Up and Go and Single-Leg Stance Test was also found in the intervention group. Exercise training focusing on the ankle is effective in enhancing the postural stability of older adults with type 2 diabetes and can potentially be effective in improving single-leg standing balance and mobility. [Journal of Gerontological Nursing, 44(2), 41-48.].

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.

Attention Deficit Hyperactivity Disorder and Motor Impairment

Attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioral disorder during childhood, affecting approximately 3–6% of school-aged children; its cardinal symptoms of high activity, impulsivity, and behavioral distractibility might be assumed to have close relationships to interferences with motor skills. A separate body of literature attests to ways that motor problems can severely impact children’s daily lives, as motor problems may occur in 30–50% of children with ADHD. This article critically reviews research on motor impairment in children with ADHD, notable differences in motor performance of individuals with ADHD compared with age-matched controls, and possible neural underpinnings of this impairment. We discuss the highly prevalent link between ADHD and developmental coordination disorder (DCD) and the lack of a clear research consensus about motor difficulties in ADHD. Despite increasing evidence and diagnostic classifications that define DCD by motor impairment, the role of ADHD symptoms in DCD has not been delineated. Similarly, while ADHD may predispose children to motor problems, it is unclear whether any such motor difficulties observed in this population are inherent to ADHD or are mediated by comorbid DCD. Future research should address the exact nature and long-term consequences of motor impairment in children with ADHD and elucidate effective treatment strategies for these disorders together and apart.

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.

Attention during functional tasks is associated with motor performance in children with developmental coordination disorder: A cross-sectional study

This cross-sectional and exploratory study aimed to compare motor performance and electroencephalographic (EEG) attention levels in children with developmental coordination disorder (DCD) and those with typical development, and determine the relationship between motor performance and the real-time EEG attention level in children with DCD.Eighty-six children with DCD [DCD: n = 57; DCD and attention deficit hyperactivity disorder (ADHD): n = 29] and 99 children with typical development were recruited. Their motor performance was assessed with the Movement Assessment Battery for Children (MABC) and attention during the tasks of the MABC was evaluated by EEG.All children with DCD had higher MABC impairment scores and lower EEG attention scores than their peers (P < 0.05). After accounting for age, sex, body mass index, and physical activity level, the attention index remained significantly associated with the MABC total impairment score and explained 14.1% of the variance in children who had DCD but not ADHD (P = 0.009) and 17.5% of the variance in children with both DCD and ADHD (P = 0.007). Children with DCD had poorer motor performance and were less attentive to movements than their peers. Their poor motor performance may be explained by inattention.

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.

Effects of high heeled shoes wearing experience and heel height on human standing balance and functional mobility

This study aimed to examine the effects of high heeled shoes (HHS) wearing experience and heel height on human standing balance and functional mobility. Thirty young and healthy females (ten experienced and twenty inexperienced HHS wearers) participated in a series of balance tests when they wore shoes of four different heel heights: 1 cm (flat), 4 cm (low), 7 cm (medium) and 10 cm (high). Experimental results show that regardless of the wearing experience, the heel elevation induces more effort from lower limb muscles (particularly calf muscles) and results in worse functional mobility starting at 7 cm heel height. While the heel height increased to 10 cm, the standing balance also becomes worse. Experienced HHS wearers do not show significantly better overall performance on standing balance and functional mobility than inexperienced controls, even though they have better directional control (76.8% vs. 74.4%) and larger maximum excursion (93.3% vs. 89.7%). To maintain standing balance, experienced wearers exert less effort on tibialis anterior, vastus lateralis and erector spinae muscles at the cost of more intensive effort from gastrocnemius medialis muscle.

PRACTITIONER SUMMARY

Many women wear high heeled shoes (HHS) to increase female attractiveness. This study shows that HHS induce more muscular effort and worse human standing balance and functional mobility, especially when heel height reaches 10 cm. HHS wearing experience only provides certain advantages to wearers on limits of stability in terms of larger maximum excursion and better directional control.

Deficits in sensory organization for postural stability in children with Tourette syndrome

Tourette syndrome (TS) is a childhood-onset developmental disorder characterized by involuntary motor and vocal tics. Previous studies have indicated that children with TS demonstrate postural control anomalies when standing. The aim of this study was to compare postural stability under normal and altered sensory conditions in children with TS and healthy control (HC) children. A convenience sample of twelve children with TS (9 boys and 3 girls; 9.4 ± 1.1 yr) and 12 HC age- and gender-matched children (9.2 ± 1.1 yr) participated in this study. The Sensory Organization Test (SOT) was used to assess postural stability under six altered sensory conditions (1. normal vision, fixed support; 2. eyes closed, fixed support; 3. vision sway-referenced, fixed support; 4. normal vision, support sway-referenced; 5. eyes closed, support surface sway-referenced; 6. both vision and support surface sway-referenced) using the SMART Balance Master® 8.2 (NeuroCom® International, Inc, Clackamas, OR, USA). The results showed significant differences between the two groups in conditions 5 and 6 (p=0.003 and 0.002, respectively). The mean composite equilibrium score in children with TS was significantly lower than that of HC children (p<0.000). The results suggested that children with TS had greater difficulty in maintaining postural stability, especially when vestibular information was challenged. The results of this study provide supporting evidence for possible deficits in impaired access to vestibular information and sensorimotor integration of postural control in children with TS.

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.

Physical literacy: importance, assessment and future directions

Physical literacy (PL) has become a major focus of physical education, physical activity and sports promotion worldwide. PL is a multifaceted conceptualisation of the skills required to fully realise potentials through embodied experience. Substantial financial investments in PL education by governments are underpinned by a wide range of anticipated benefits, including expectations of significant future savings to healthcare, improved physical and psychological well-being of the population, increased work-force productivity and raised levels of expertise in sport and exercise participation. However, disappointingly, scientific evidence showing the efficacy of PL interventions to successfully meet such high expectation is limited. We suggest that contradictions in research findings are due largely to limitations in movement assessment batteries and consequent discrepancies between measurements used to assess the immediate outcomes of PL programmes. Notably, there is no robust empirical tool for evidencing skill learning in the physical movement component of PL, education and this presents a serious limitation to the design of, and claims that can be made for, such interventions. Considering the parameters of proficient PL skills and the limitations of current evaluation instruments, possible future directions for developing empirical measures of PL movement skills are presented.

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.

Developmental coordination disorders: state of art

In the literature, descriptions of children with motor coordination difficulties and clumsy movements have been discussed since the early 1900s. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), it is a marked impairment in the development of fine or global motor coordination, affecting 6% of school-age children. All these children are characterized for developmental coordination disorder (DCD) in motor learning and new motor skill acquisition, in contrast to adult apraxia which is a disorder in the execution of already learned movements. No consensus has been established about etiology of DCD. Intragroup approach through factor and cluster analysis highlights that motor impairment in DCD children varies both in severity and nature. Indeed, most studies have used screening measures of performance on some developmental milestones derived from global motor tests. A few studies have investigated different functions together with standardized assessments, such as neuromuscular tone and soft signs, qualitative and quantitative measures related to gross and fine motor coordination and the specific difficulties -academic, language, gnosic, visual motor/visual-perceptual, and attentional/executive- n order to allow a better identification of DCD subtypes with diagnostic criteria and to provide an understanding of the mechanisms and of the cerebral involvement.

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

This study aimed to (1) compare the postural control strategies, sensory organization of balance control, and lower limb muscle performance of children with and without developmental coordination disorder (DCD) and (2) determine the association between postural control strategies, sensory organization parameters and knee muscle performance indices among children with DCD. Fifty-eight DCD-affected children and 46 typically developing children participated in the study. Postural control strategies and sensory organization were evaluated with the sensory organization test (SOT). Knee muscle strength and time to produce maximum muscle torque (at 180°/s) were assessed using an isokinetic machine. Analysis of variance was used to compare the outcome variables between groups, and multiple regression analysis was used to examine the relationships between postural control strategies, sensory organization parameters, and isokinetic indices in children with DCD. The DCD group had significantly lower strategy scores (SOT conditions 5 and 6), lower visual and vestibular ratios, and took a longer time to reach peak torque in the knee flexor muscles than the control group (p>0.05). After accounting for age, sex, and body mass index, the vestibular ratio explained 35.8% of the variance in the strategy score of SOT condition 5 (p<0.05). Moreover, the visual ratio, vestibular ratio, and time to peak torque of the knee flexors were all significant predictors (p<0.05) of the strategy score during SOT condition 6, accounting for 14, 19.7, and 19.8% of its variance, respectively. The children with DCD demonstrated deficits in postural control strategy, sensory organization and prolonged duration of muscle force development. Slowed knee muscle force production combined with poor visual and vestibular functioning may result in greater use of hip strategy by children with DCD in sensory challenging environments.

Differential effect of Taekwondo training on knee muscle strength and reactive and static balance control in children with developmental coordination disorder: a randomized controlled trial

This randomized controlled trial aimed to investigate the effect of short-term intensive TKD training on the isokinetic knee muscle strength and reactive and static balance control of children with developmental coordination disorder (DCD). Among the 44 children with DCD (mean age: 7.6 ± 1.3 years) recruited, 21 were randomly assigned to undergo daily TKD training for 1h over three consecutive months, with the remaining 23 children being assigned to the DCD control group. Eighteen typically developing children (mean age: 7.2 ± 1.0 years) received no training as normal controls. Knee extensor and flexor muscle strength and reactive and static balance control were assessed using an isokinetic machine (with low, moderate and high movement velocities), a motor control test (MCT) and a unilateral stance test (UST), respectively. A repeated measures MANCOVA revealed a significant group through time interaction effect in isokinetic outcomes at 180°/s and in the UST outcome. Post hoc analysis demonstrated that DCD-TKD children's isokinetic knee muscle strength, specifically at 180°/s, was as high as that of the normal control children (p>0.0083) after TKD training. Moreover, UST body sway velocity was slower in the DCD-TKD group than in the DCD control group (p<0.001), and was comparable to that of the normal control group (p>0.05) after TKD training. However, no such improvement in balance was observed in the MCT (p>0.025). The results show that children with DCD who undergo a 3-month program of intensive TKD training experience improvements in isokinetic knee muscle strength at 180°/s and static single-leg standing balance control, but do not benefit from improved reactive balance control.