Qualitative age-related changes in fine motor skill performance among 3- to 6-year-old typically developing children.

This study described intra-task fine motor skill components of the Manual Dexterity tasks (Posting Coins; PC, Threading Beads; TB, Drawing Trail; DT) of the Movement Assessment Battery for Children-2 Test for typically developing children and investigated age- and sex-related differences. Three- to six-year-old Dutch children (n = 182, Mage 4.5 ± 1.1 years, 51.1% boys) were observed with regard to intra-task fine motor skill components, and changes in intra-task components of the Manual Dexterity tasks were analyzed across age using of the Kruskal-Wallis test with post-hoc Mann-Whitney U tests, and differences between sexes using the Mann-Whitney U test. The following intra-task components were observed: grip type, manipulation, non-dominant or non-writing hand, grip position, posture, head, coin placement, placement of the bead on the lace tip and joint movement. Results showed that the younger children (3-year-olds) more frequently used a grasp with the full hand (PC, TB), more often put the coin on the container and sliding it in (PC), more often supported the side or top of the container (PC), used more bi-manual manipulation (transferring from hand-to-hand or hand, body or surface assist) (TB, DT), more frequently used primitive, too high grips, predominantly used their proximal joints, and did not support the paper (DT). This in comparison with more frequent use of three-point pinch, direct coin placement, grabbing the front or back of the container, in-hand-manipulation, mature grips and correct height, distal joint use and supporting the paper from the side or below by most 5- and 6-year-olds. Furthermore, most sex-related differences were found in the younger age-groups (3- and 4-year-olds) in the DT tasks with girls outperforming boys. Results from this study add to the knowledge on qualitative fine motor skill performance in a convenience sample of 3- to 6-year-old typically developing children. A limitation of the current study was the relatively small sample size of 6-year-old children. The strength of the current study is its novelty in providing qualitative descriptions of intra-task fine motor skill components in typically developing 3- to 6-year-old children.

Effectiveness of different extrinsic feedback forms on motor learning in children with cerebral palsy: a systematic review.

PURPOSE: Motor learning interventions for children with cerebral palsy (CP) that elicit relatively permanent and transferable improvements in motor skill capability are essential. Knowledge is needed about the augmented feedback forms that most effectively promote this. This review aims to collect and analyze the current evidence for the effectiveness of different forms of feedback for motor learning in children with CP to improve motor task performance. METHODS: PubMed, PsycInfo, and Cochrane Library were searched to identify relevant studies. Studies were included if (1) they were conducted in children with CP or compared children with CP to TD children and (2) a form of augmented feedback related to a motor task was administered. RESULTS: Initially, 401 records were identified for screening. Ultimately, 12 articles were included in the review. The evidence thus far supports the expectancy that children with CP generally benefit from feedback provided during or after performing a movement task. CONCLUSION: Due to the heterogeneity of existing studies, it is difficult to draw firm conclusions regarding relative effectiveness of feedback forms. This review showed that more high-quality research is warranted on the effectiveness of specific feedback forms on motor learning in children with CP.Implications for RehabilitationChildren with CP benefit from several forms of knowledge of performance or knowledge of results feedback provided during or after performing a movement task.Feedback should not be provided with every performed trial.Feedback frequency can best be reduced by letting children determine after which trials they want feedback.Learning curves under similar feedback conditions varied largely between children, warranting tailor-made forms of feedback to be applied during motor learning and rehabilitation.

The subtypes of developmental coordination disorder.

AIM: To identify subtypes in a large group of children clinically diagnosed with developmental coordination disorder (DCD) based on their pattern of motor, cognitive, and visual-motor abilities. METHOD: Standardized scores for verbal IQ, total IQ, Movement Assessment Battery for Children, Second Edition (MABC-2) balance, MABC-2 manual dexterity, MABC-2 ball skills, and Beery-Buktenica Developmental Tests of Visual-Motor Integration (Beery-VMI), Motor Coordination (Beery-MC), and Visual Perception (Beery-VP) were used. The NbClust complete procedure was used to best partition the data on 98 children (84 males, 14 females, mean [SD] age: 8 years [2 years 1 month]) into clusters. Deviation contrasts, multivariate analysis of variance, and post hoc comparisons were used to characterize the clusters. RESULTS: Four clusters were revealed: two clusters with a broad motor skill problem, one with relatively preserved visual-motor integration and Beery-MC skills, and a second with abnormal ball skills, balance, and Beery-MC skills. A third cluster with more specific gross-motor problems, and a fourth with relatively preserved ball skills but low Beery-MC and performance IQ, were identified. Balance scores were 'at risk' or 'abnormal' in all four clusters. INTERPRETATION: DCD is a heterogeneous condition. However, subtypes can be discriminated on the basis of more severe difficulties in fine-motor performance, gross-motor performance, or both. There was evidence for generalized motor impairments in around half of all children. Importantly, at least borderline level reduced balance was evident in each subtype. WHAT THIS PAPER ADDS: Four subtypes were identified in a large clinical group of children with developmental coordination disorder (DCD). Subtypes were based on motor, cognitive, and visual-motor abilities. There was evidence of generalized motor impairments in around 50% of children with DCD. A generalized balance problem is present across all subtypes of DCD.

Effectiveness and feasibility of We12BFit!: improving physical fitness and lifestyle physical activity in children with developmental coordination disorder in a paediatric rehabilitation setting-a small sample field study.

OBJECTIVES: To examine the effectiveness and feasibility of We12BFit!, a family-focused intervention aimed at increasing physical fitness (PF) and motivation for physical activity (PA) in 7-year-old to 12-year-old children with developmental coordination disorder (DCD). DESIGN: A single-arm mixed methods small sample field study. SETTING: Rehabilitation centres and schools for special education in The Netherlands. PARTICIPANTS: Twenty children with DCD diagnosis. INTERVENTIONS: We12BFit! consists of We12BFit!-PF and We12BFit!-Lifestyle PA. During We12BFit!-PF, cardiorespiratory fitness (CRF), muscle strength and anaerobic power were trained in small groups (10 weeks 2*60 min/week). We12Bfit!-Lifestyle PA, which addresses motivation for PA in children and parents, was added in week 6 of We12BFit!-PF and ended 12 weeks after We12BFit!-PF. OUTCOME MEASURES: The 20-Metre Shuttle Run Test (20mSRT), Muscle Power Sprint Test and Hand Held Dynamometry were performed before and after We12BFit!-PF and after We12BFit!-Lifestyle PA (T0-T1-T2). Parents and coaches were interviewed and trainers participated in a focus group to assess motivation for PA, perceived effectiveness, and feasibility of the intervention. RESULTS: Attendance rates of participants were 88% (We12BFit!-PF) and 89% (We12BFit!-Lifestyle PA). From T0 to T1, significant improvements were found in VO2peak, number of runs on the 20mSRT and mean anaerobic power. From T1 to T2, improvements were maintained. No changes were found after We12BFit!-Lifestyle PA in time spent on moderate to vigorous activity and metabolic equivalent of task; parents observed their child improved in qualitative aspects of activities and participation. Feasibility of We12Bfit! was confirmed, although some adaptations were recommended. CONCLUSIONS: We12BFit! resulted in significant improvements and maintenance of CRF and anaerobic power in a small group of children with DCD and seemed to improve motivation for PA. The group aspect of We12BFit!-PF, the high intensity and positive motivational climate of We12BFit!-PF may have improved children's self-efficacy. We12BFit! seems feasible to improve PF and PA in children with DCD. TRIAL REGISTRATION NUMBER: NTR6334.

The diagnostic trajectory of developmental coordination disorder in the Netherlands: Experiences of mothers.

BACKGROUND: Receiving a diagnosis can have a major impact on the child and its family. Parental satisfaction concerning the diagnostic trajectory is important with regard to acceptance and coping with their child's problems. Our aim was to describe the diagnostic trajectory of developmental coordination disorder (DCD) in the Netherlands and identify factors that are related to parents' satisfaction. METHOD: Mothers of 60 children with a DCD diagnosis completed an online survey concerning their experiences during and after the diagnostic trajectory of obtaining this diagnosis. RESULTS: Forty percent of the mothers rated the diagnostic trajectory towards a DCD diagnosis as stressful and 47% rated the knowledgeability of the first professional they consulted (mostly a general practitioner, paediatric physical therapist, or youth health care physician) as having no or just superficial knowledge about DCD. Around 60% of the mothers described a lack of knowledge and support at their child's school after receiving the diagnosis. Notwithstanding this, the majority of the participating mothers was (very) satisfied with the diagnostic trajectory. Higher appreciation of both the manner of the diagnosing professional and the post-diagnostic support provided were predictive of higher satisfaction. CONCLUSIONS: Our results underline the importance of improving the knowledgeability in primary schools and primary health care professionals with regard to DCD.

Motor performance and daily participation in children with and without probable developmental coordination disorder.

AIM: To test the mediating role of motor performance in the relationship between individual and environmental constraints, delayed learning of activities of daily living (ADL), and daily participation in typically developing children and children with probable developmental coordination disorder (DCD). METHOD: Parents of 370 randomly selected children aged 5 to 10 years (194 females; mean age [SD] 7y 5mo [1y 10mo]) were included in the study (321 typically developing, 49 probable DCD). Motor performance, ADL learning, and participation were assessed using the DCDDaily-Questionnaire. Individual variables included child's age and sex, and environmental variables included mother and family educational level, presence of siblings, and area of residence. Direct, indirect, and mediating effects were tested using a partial least squares-based structural equation modelling approach. RESULTS: The model explained 44.5% of the variance of daily participation. Motor performance significantly mediated the effect of individual and environmental constraints, and ADL learning on daily participation. INTERPRETATION: Results suggest that the effect of individual and environmental constraints and delayed learning of ADL on daily participation is mediated by motor performance in typically developing children and children with probable DCD. These findings provide further evidence that interventions to promote participation in children with probable DCD should adopt ecological, task-oriented approaches. Further studies should evaluate model generalizability with clinical samples.

The Relationship between Social Environmental Factors and Motor Performance in 3- to 12-Year-Old Typically Developing Children: A Systematic Review.

Motor performance during childhood is important for prosperity in life, and the social environment may contain potentially important and modifiable factors associated with motor performance. Therefore, the aim of this systematic review was to identify social environmental factors associated with motor performance in 3- to 12-year-old typically developing children. Four electronic databases were searched, which resulted in 31 included studies. The methodological quality was determined using the Quality of Prognosis Studies in Systematic Reviews tool. Most studies were conducted in 3-6-year-old children. In the home environment, parental beliefs in the importance of physical activity and parental behaviors matching these beliefs were related to better motor performance of children, although these relationships were often sex-dependent. The school and sports environments were investigated much less, but some preliminary evidence was found that being better liked by peers, attending a classroom with a smaller age range, having more interaction with the teacher and classmates, and having a higher educated teacher was related to better motor performance. Further research is required to further unravel the relationship between the social environment and motor skills, with a specific focus on 6-12-year-old children and environments outside of the home environment.

The Relationships between Sibling Characteristics and Motor Performance in 3- to 5-Year-Old Typically Developing Children.

Siblings have been hypothesized to positively impact the motor performance of children by acting as examples and by providing a safe environment, but they may also negatively impact motor performance because they could compete for the parent's time and care. Therefore, this study investigates the relationship between several sibling characteristics and motor performance in 3- to 5-year-old children. The sample consisted of 205 3- to 5-year-old children (mean age 50.9 ± 10.0 months, 52.2% boys). The Movement Assessment Battery for Children-2 was used to measure motor performance. The sibling variable was operationalized as the number of siblings present, the age difference between a child and its siblings, and the birth order position of a child. The confounding variables that were taken into account were the age, sex, and behavioral problems of the child and maternal education level. None of the investigated sibling variables were related to the total motor performance of a child after controlling for possible confounding variables. The absence of any associations between the sibling variables and motor performance might be explained by the characteristics of the study sample, the possibility that there is no linear relationship, or the presence of still unknown moderating or mediating factors.

Risk factors in early life for developmental coordination disorder: a scoping review.

AIM: To perform a scoping literature review of associations between risk factors in early life and developmental coordination disorder (DCD). METHOD: PubMed, Embase, CINAHL, PsycINFO, and Web of Science (January 1994-March 2019) were searched to identify studies on early risk factors and motor impairment or DCD. The effect of single and multiple risk factors was assessed. Level of evidence was evaluated following the Centre for Evidence-Based Medicine guidelines. Meta-analysis on the effect of preterm birth was performed. RESULTS: Thirty-six studies fulfilled inclusion criteria; 35 had evidence level 3, one had level 4. Highest evidence was available that preterm birth and male sex in term-born children were associated with DCD. The odds ratio of preterm birth was 2.02 (95% confidence interval: 1.43-2.85). Low to moderate evidence was available that parental subfertility, maternal smoking during pregnancy, postnatal corticosteroid treatment in infants born preterm, extra corporeal membrane oxygenation, retinopathy of prematurity, abnormalities on magnetic resonance imaging scans at term age, and accumulating perinatal or neonatal risk factors were associated with motor impairment. INTERPRETATION: Limited information on early risk factors of DCD is available. Only preterm birth and male sex were consistently associated with an increased risk of DCD. WHAT THIS PAPER ADDS: Preterm birth is a risk factor for developmental coordination disorder (DCD). In term-born children, male sex was consistently associated with DCD. Risk factors for DCD are similar to risk factors for cerebral palsy.

The nature of coordination and control problems in children with developmental coordination disorder during ball catching: A systematic review.

The aim of this review was to examine what is presently known about the nature of motor coordination and control problems in children with developmental coordination disorder (DCD) during ball catching and to provide directions for future research. A systematic literature search was conducted using four electronic databases (PubMed, Embase, PsycINFO and Web of Science), which identified 15 eligible studies. The results of the included studies were discussed, structured around the target population characteristics, the task used to measure motor coordination and control aspects, and the type of outcome. Children with DCD experience difficulties with both motor coordination and control during ball catching. They have been suggested to apply four compensation strategies to overcome these difficulties: a later initiation of the reaching phase, an earlier initiation of the grasping phase, a higher degree of coupling of the joints both intra- and inter-limb, and fixating the joints. However, despite these compensation strategies, children with DCD still caught fewer balls than typically developing children in all studies. This was especially due to a higher amount of grasping errors, which indicates a problem with the timing of the grasping phase. Directions for future research and practical implications were discussed.

Assessment of Motor Activities of Daily Living: Spanish Cross-Cultural Adaptation, Reliability and Construct Validity of the DCDDaily-Q.

The DCDDaily-Q is an instrument that aims to comprehensively assess motor performance in a broad range of activities of daily living (ADL) and to identify risk of Developmental Coordination Disorder (DCD) in children. The aim of this study was to cross-culturally adapt the DCDDaily-Q into European Spanish (DCDDaily-Q-ES) and to test its psychometric properties in Spanish 5 to 10 year old children. The DCDDaily-Q was translated and cross-culturally adapted into Spanish following international guidelines. Two-hundred and seventy-six parents of typically developing Spanish children completed the final version of the DCDDaily-Q-ES (M = 7.5 years, SD = 1.7; girls = 50%). Confirmatory Factor Analysis (CFA), internal consistency, and corrected item-total correlations were conducted to test construct validity, internal consistency, and homogeneity of the DCDDaily-Q-ES. The DCDDaily-Q-ES achieved good semantic, conceptual, and cultural equivalence. CFA supported construct validity of the DCDDaily-Q-ES. Reliability values were also good (Cronbach's alpha = 0.703-0.843; corrected item-total correlations = 0.262-0.567). This is the first study to cross-culturally adapt and examine the DCDDaily-Q outside the Netherlands. The findings suggest that the DCDDaily-Q-ES is a reliable and valid measure to assess learning, participation, and performance in a broad range of ADL.

Interrelation of Individual, Country and Activity Constraints in Motor Activities of Daily Living among Typically Developing Children: A Cross-sectional Comparison of Spanish and Dutch Populations.

Motor performance is influenced by individual, environmental, and task constraints. Children perform differently according to individual (i.e., sex), environmental (i.e., country), and task (i.e., type of activity) factors. However, little is known about the effect of the interaction between sex and country factors across different activities of daily living (ADL) learning, participation, and performance. The main aim of this study was to examine the relationship between sex, country, and type of activity in motor-based ADL learning, participation, and performance in five-to-eight-year-old, typically developing children. Additionally, we aimed to compare the prevalence of probable Developmental Coordination Disorder (DCD) across sex and country. The DCDDaily-Q was used to assess ADL learning, participation, and performance in 300 age and sex-matched children from Spain and The Netherlands. The prevalence of probable DCD was determined based on the total ADL performance score. Results showed that differences in ADL learning, participation and performance differed across sex and country (p < 0.05). Prevalence of probable DCD was statistically similar in both countries. These findings show that daily participation and performance in typically developing children may be influenced by individual, country, and task constraints, and that country and sex may have different influences on particular tasks.

Identifying Children with Developmental Coordination Disorder via Parental Questionnaires. Spanish Reference Norms for the DCDDaily-Q-ES and Correlation with the DCDQ-ES.

Developmental Coordination Disorder (DCD) is one of the most prevalent neurodevelopmental disorders in school-aged children, with major consequences in psychosocial and physical health. Adequate identification of this disorder is necessary to prompt effective interventions. The aims of this study were to develop the Spanish adjusted reference norms for the DCDDaily-Q and to test the correlation and agreement between the Spanish versions of the DCDDaily-Q (DCDDaily-Q-ES) and the Developmental Coordination Disorder Questionnaire (DCDQ-ES), two reliable instruments to assess motor performance and DCD. Clinically relevant percentiles were calculated for the DCDDaily-Q-ES using a representative sample of Spanish children aged 5 to 10 years (n = 356; M = 7.3 years, SD = 1.8; boys = 50%). Pearson's correlation coefficient and intraclass correlation coefficient (ICC) were used to determine correlation and agreement between questionnaires, respectively. A moderate and significant correlation and agreement between DCDDaily-Q-ES and DCDQ-ES was found (r = 0.406; ICC = 0.381; p < 0.001). Differences in daily participation and performance were found between age groups, but not between boys and girls. Spanish age-adjusted percentiles and cutoff scores for DCDDaily-Q-ES are provided. This study offers further validation and relevant information regarding assessment of DCD and has practical implications for clinical practice and research.

We12BFit!-Improving lifestyle physical activity in children aged 7-12 years with developmental coordination disorder: protocol of a multicentre single-arm mixed-method study.

INTRODUCTION: Children with developmental coordination disorder (DCD) are less physically active than their typically developing peers. No substantiated interventions are available to address this issue. Therefore, this study aims to describe the design and rationale of (1) a family-focused intervention to increase motivation for physical activity (PA) and, indirectly, lifestyle PA in children aged 7-12 years with DCD and (2) the methods to examine its preliminary effectiveness and feasibility. METHODS AND ANALYSIS: This intervention is the second part of a more comprehensive, multidisciplinary treatment called We12BFit! The intervention was developed using the steps of treatment theory which includes the concept of targets, mechanism of action and essential ingredients. The content of the intervention is based on the transtheoretical model of change (TTM). In the intervention, the motivation for PA will be targeted through application of behaviour change strategies that fit the stages of the TTM. The modes of delivery include: pedometer, poster, parent meeting, booklet and coaching. At least 19 children with DCD, aged 7-12 years, will be included from two schools for special education and two rehabilitation centres. The intervention will be evaluated using a single-arm mixed-method design. Effectiveness will be assessed at three instances by using ActiGraph accelerometers accompanied by an activity log. Feasibility will be assessed using interviews with the participants and coaches. This evaluation may add to our understanding of motivation for PA in children with DCD and may eventually improve the rehabilitation programme of children with DCD. ETHICS AND DISSEMINATION: The study has been approved by the Medical Ethics Committee of the University Medical Center of Groningen (METc 2015.216). We will disseminate the final results to the public through journal publications and presentations for practice providers and scientists. A final study report will also be provided to funding organisations. PROTOCOL VERSION: 4, 12 April 2018. TRIAL REGISTRATION NUMBER: NTR6334; Pre-results.

Variability in coordination patterns in children with developmental coordination disorder (DCD).

High motor variability is an often-found characteristic of Developmental Coordination Disorder (DCD). Still, the role of high motor variability in DCD needs further examination. This study focused on variability in coordination patterns, which is essential considering that DCD is a coordination disorder. We examined variability in coordination patterns of the arm over repetitions of trials in goal-directed reaching movements. This variability was partitioned into variability that does not affect the index fingertip position (Vucm) and variability that does affect the index fingertip position (Vort). This study aimed to increase the understanding of motor variability in DCD by comparing Vucm and Vort between children with DCD and typically developing (TD) children in a goal-directed reaching task. Twenty-two children (eleven with DCD) ages 6-11 performed 30 reaching movements. The Uncontrolled Manifold method was used to quantify Vucm and Vort. Results showed that children with DCD had more Vucm than TD children while Vort was similar between groups, showing that coordination patterns in children with DCD are more variable, but interestingly, this higher variability does not affect performance. This study indicates that high motor variability in DCD is not necessarily negative. Possible roles of motor variability in DCD are discussed.

The development of consistency and flexibility in manual pointing during middle childhood.

Goal-directed actions become truly functional and skilled when they are consistent yet flexible. In manual pointing, end-effector consistency is characterized by the end position of the index fingertip, whereas flexibility in movement execution is captured by the use of abundant arm-joint configurations not affecting the index finger end position. Because adults have been shown to exploit their system's flexibility in challenging conditions, we wondered whether during middle childhood children are already able to exploit motor flexibility when demanded by the situation. We had children aged 5-10 years and adults perform pointing movements in a nonchallenging and challenging condition. Results showed that end-effector errors and flexibility in movement execution decreased with age. Importantly, only the 9-10-year-olds and adults showed increased flexibility in the challenging condition. Thus, while consistency increases and flexibility decreases during mid-childhood development, from the age of nine children appear able to employ more flexibility with increasing task demands.

Development of reaching during mid-childhood from a Developmental Systems perspective.

Inspired by the Developmental Systems perspective, we studied the development of reaching during mid-childhood (5-10 years of age) not just at the performance level (i.e., endpoint movements), as commonly done in earlier studies, but also at the joint angle level. Because the endpoint position (i.e., the tip of the index finger) at the reaching target can be achieved with multiple joint angle combinations, we partitioned variability in joint angles over trials into variability that does not (goal-equivalent variability, GEV) and that does (non-goal-equivalent variability, NGEV) influence the endpoint position, using the Uncontrolled Manifold method. Quantifying this structure in joint angle variability allowed us to examine whether and how spatial variability of the endpoint at the reaching target is related to variability in joint angles and how this changes over development. 6-, 8- and 10-year-old children and young adults performed reaching movements to a target with the index finger. Polynomial trend analysis revealed a linear and a quadratic decreasing trend for the variable error. Linear decreasing and cubic trends were found for joint angle standard deviations at movement end. GEV and NGEV decreased gradually with age, but interestingly, the decrease of GEV was steeper than the decrease of NGEV, showing that the different parts of the joint angle variability changed differently over age. We interpreted these changes in the structure of variability as indicating changes over age in exploration for synergies (a family of task solutions), a concept that links the performance level with the joint angle level. Our results suggest changes in the search for synergies during mid-childhood development.

We12BFit!-Improving Physical Fitness in 7-12-Year-Old Children With Developmental Coordination Disorder: Protocol of a Multicenter Single-Arm Mixed-Method Study.

Background: Children with developmental coordination disorder (DCD) are less physically fit than their typically developing peers. No substantiated treatments are available for children with DCD to address this issue. Aims: This study aims to describe 1. the design and rationale of We12BFit!-PF, a training to increase cardiorespiratory fitness, muscle strength and anaerobic power in 7-12-year-old children with DCD and 2. the methods to examine its preliminary effectiveness and feasibility. Methods: We12BFit!-PF was developed using the steps of defining a treatment theory as proposed by Whyte et al. This includes the definition of targets, mechanisms of action, and essential ingredients. We12BFit!-PF will be evaluated in children diagnosed with DCD according to the criteria of the Diagnostic and Statistical Manual of mental disorders (DSM-V) aged 7-12, recruited from rehabilitation centers and physical therapy clinics. Indication for participation will be a need related to enhancing PF, for example tiring quickly, being quickly out of breath or being unable to keep up with peers during PA. During the treatment the participants will be engaged in a group training (2 × 60 min/week, 10 weeks) targeting cardiorespiratory fitness using high intensity interval training, muscle strength using exercises without weights and anaerobic power using plyometrics. Training intensity during high intensity interval training will be monitored with heart rate monitors, if necessary the intensity will be adjusted. Using a single-arm mixed-method design, the preliminary effectiveness will be determined using the 20 meter Shuttle Run Test, hand held dynamometry (JAMAR and MicroFET) and the Muscle Power Sprint Test, which will be assessed in week 0, 11, and 23. Feasibility will be assessed by interviewing parents and children and by organizing a focus group session with the trainers at the end of We12BFit!-PF. Based on a 5% improvement in VO2peak the minimum sample size is 19 children. Ethics and dissemination: The University of Groningen, University Medical Center Groningen medical ethics committee approved the study (METC 2015.216). Final results will be disseminated via scientific publications, presentations and congress proceedings. Funding organizations will receive a final study report. Trial Registration: This study was registered with Netherlands Trial Registry (NTR6334, www.trialregister.nl).

Characteristics of physical activity interventions and effects on cardiorespiratory fitness in children aged 6-12 years-A systematic review.

OBJECTIVES: To examine the characteristics of physical activity (PA) interventions and the effects on cardiorespiratory fitness (CRF) in healthy children based on treatment theory. DESIGN: Systematic review. METHODS: PubMed and Embase were searched for studies published between 2003 and 2016. Inclusion criteria were: Participants: healthy children aged 6-12. INTERVENTIONS: interventions with activities to increase PA behaviour or physical fitness (PF) regardless of setting. CONTROL: no or alternative intervention. OUTCOME: exercise-based CRF measure with appropriate analysis of CRF effects. STUDY DESIGN: randomized controlled trial. Effect size was calculated using dppc2 and the methodological quality of the studies was assessed using the PEDro scale. RESULTS: Of 1002 studies screened, 23 met the inclusion criteria. Thirteen of the 23 studies found statistically significant improvements in CRF and eight studies showed medium to high effect sizes. Interventions with medium to high effect sizes focused more often on PF than PA behaviour, had slightly higher frequencies of activities and had a shorter duration than the less effective interventions. CONCLUSIONS: The fact that thirteen studies demonstrated statistically significant improvements in CRF is promising but also emphasizes the need to keep improving research methods and the development and execution of interventions. Interventions with larger effect sizes appear to be more controlled, as they usually relied on smaller sample sizes and the components of these interventions encompassed protocolled training sessions which defined and monitored the relative training intensity intended. A duration of at least six weeks and a frequency of three to four times a week is recommended.