When and for whom are relative age effects important? Evidence from a simple test of cardiorespiratory fitness.

OBJECTIVES: When individuals of different ages are combined into a single group and an ability that varies with age is measured, younger individuals are disadvantaged. This phenomenon is known as a relative age effect (RAE) and has been shown to be widespread in sport and education. METHODS: In this article, we examine RAEs in a large group of children tested repeatedly on the 20-m shuttle run, a common test of cardiorespiratory fitness. Following up on an earlier study that measured change with age, we add a growth curve model for change in variance, which makes it possible to derive RAEs for individuals of different ages and ability levels. RESULTS: Results show that a 1-year difference in age is associated with a change in performance of about 0.2 standard deviations. For 1-year age groups, this gives rise to ranking errors of 4 percentile ranks or less. We also show, however, that these relatively small ranking errors are capable of producing large age differences within groups identified as exceptional. Depending on the level of ability required for selection, children born in the first quarter of the year can be expected to outnumber those born in the last by 1.5 times, 2 times, or more. This finding is consistent with previously reported variation in RAEs at different performance levels. CONCLUSIONS: Results imply that RAEs are likely to be of relatively minor concern when people are graded or ranked but can produce substantial inequities and misclassifications when people with extremely high or extremely low ability levels undergo selection.

The Otto Aufranc Award. On the etiology of the cam deformity: a cross-sectional pediatric MRI study.

BACKGROUND: Femoroacetabular impingement (FAI) has been recognized as a common cause of hip pain as well as a cause of hip arthritis, yet despite this, little is known about the etiology of the cam morphology or possible risk factors associated with its development. QUESTIONS/PURPOSES: The purposes of our study were to determine when the cam morphology associated with FAI developed in a cross-sectional cohort study of pediatric patients pre- and postphyseal closure using MRI and whether increased activity level during the period of physeal closure is associated with an increased likelihood that the cam deformity will develop. METHODS: Alpha angles were measured at the 3 o'clock (anterior head-neck junction) and 1:30 (anterosuperior head-neck junction) positions in both hips with a cam deformity defined as an alpha angle ≥ 50.5° at the 3 o'clock position. Forty-four volunteers (88 hips) were studied: 23 with open physes (12 females, mean age 9.7 years; 11 males, age 11.7 years) and 21 with closed physes (five females, age 15.2 years; 16 males, age 16.2 years). Daily activity level using the validated Habitual Activity Estimation Scale was compared for patients in whom cam morphology did and did not develop. RESULTS: None of the 23 (0%) patients prephyseal closure had cam morphology, whereas three of 21 (14%, p = 0.02; all males) postclosure had at least one hip with cam morphology. Daily activity level was higher (p = 0.02) for patients with the cam morphology (7.1 hours versus 2.9 hours). Mean alpha angles at the 3 o'clock head-neck position were 38° (95% confidence interval [CI], 37.2°-39.1°) in the open physes group and 42° (95% CI, 40.16°-43.90°) in the closed physes group; at the 1:30 head-neck position, they were 45° (95% CI, 44.0°-46.4°) in the open physes group and 50° (47.9°-52.3°) in the closed physes group. CONCLUSIONS: The fact that cam morphology was present exclusively in the closed physeal group strongly supports its development during the period of physeal closure with increased activity level as a possible risk factor.

Developmental coordination disorder, sex, and activity deficit over time: a longitudinal analysis of participation trajectories in children with and without coordination difficulties.

AIM: Children with developmental coordination disorder (DCD) are known to participate in active play less than typically developing children. However, it is not known whether the activity deficit between children with and without DCD widens or diminishes over time. METHOD: Data were obtained from a large, prospective cohort study of children (baseline n=2278, total n=2470). Motor coordination was assessed for 2083 students using the short form of the Bruininks-Oseretsky Test of Motor Proficiency. Participation in organized and free-play activities was assessed using a participation questionnaire on five occasions over 3 years. Mixed-effects modelling was used to examine differences in participation over time between children with probable DCD (pDCD, n=111, 46 males, 65 females) and their typically developing peers (n=1972, 1016 males, 956 females). The mean age for the whole sample was 9 years 11 months (SD 5 mo) at assessment 1, 10 years 5 months (SD 5 mo) at assessment 2, 10 years 11 months (SD 5 mo) at assessment 3, 11 years 4 months (SD 4 mo) at assessment 4, and 11 years 11 months (SD 4 mo) at assessment 5. RESULTS: Children with pDCD reported less participation in organized and free-play activities than their typically developing peers, and these differences persisted over time. Among males, the gap in participation in free-play activities between those with DCD and typically developing children diminished substantially over time; among females, it increased slightly. INTERPRETATION: DCD is associated with a persistent activity deficit in children. Its effect on participation appears to be particularly serious among females but may diminish with time among males.

Comparison of anthropometry and parent-reported height and weight among nine year olds.

BACKGROUND: There is mounting evidence that the prevalence of overweight and obesity in children is reaching epidemic proportions in North America. We compared parent-report vs. measured BMI overweight and obesity prevalence estimates among 9 year olds using the 1996 NLSCY reports published by Willms et al. (2003) and anthropometric measurements from a regional population of public school children. METHODS: Body mass index (BMI) was calculated for 1,497 9-year-old children (males N = 734; females N = 763) from 75 public schools in the Niagara Region of Ontario, Canada. BMI from the 1996 NLSCY was based on parental reports of height and weight of 879 nine year olds. To define overweight and obese children, we used internationally accepted age- and gender-specific cut-offs as defined by Cole et al. (2000). RESULTS: The NLSCY overweight prevalence estimates of boys and girls may overestimate overweight boys and girls by 17% and 10%, respectively. Measured obesity prevalence estimates were similar to parent-reports. CONCLUSIONS: Our results suggest that parental reports of height and weight may inflate prevalence estimates of overweight children, but appear reasonably accurate for estimating obesity. Since prevalence of overweight and obesity are often combined to form a global estimate, reliance on parent-reported height and weight may overstate the magnitude of the problem.

Longitudinal examination of objectively-measured physical activity and sedentary time among children with and without significant movement impairments.

BACKGROUND: Children with Developmental Coordination Disorder (DCD) tend to be less active than typically-developing (TD) children. Current evidence, however, is based on cross-sectional and self-reported activity, and little is known about sedentary time among children with significant movement impairments such as DCD. The current study examines the longitudinal patterns of objectively measured physical activity and sedentary time in children with and without possible DCD (pDCD). METHODS: Data is from a longitudinal nested case-control study, with 103 participants (n=60 males ages=12 and 13 at baseline). Participants averaging ⩽16th percentile on the Movement Assessment Battery for Children were considered having significant movement impairments and pDCD (n=49). All participants wore accelerometers for seven days. RESULTS: There were significant main effects for time (Estimate=-23.98, p<.01) and gender (Estimate=59.86, p<.05) on total physical activity, and time spent being sedentary (Estimate=15.58, p<.05). Significant main effects for pDCD (Estimate=-5.38, p<.05) and gender (Estimate=26.89, p<.01), and time by gender interaction (Estimate=-7.50, p<.05) were found for moderate-to-vigorous physical activity (MVPA). Sedentary time did not differ between children with and without DCD. CONCLUSIONS: Results suggest children with pDCD engaged in less MVPA compared to TD children. Consistent patterns of MVPA over time, however, suggest that the divergence in MVPA occurs earlier in childhood. Further longitudinal research following a younger cohort is necessary to identify the specific point that differences in MVPA emerge.

The Canadian Assessment of Physical Literacy: Development of a Model of Children's Capacity for a Healthy, Active Lifestyle Through a Delphi Process.

BACKGROUND: The Canadian Assessment of Physical Literacy (CAPL) was conceptualized as a tool to monitor children's physical literacy. The original model (fitness, activity behavior, knowledge, motor skill) required revision and relative weights for calculating/interpreting scores were required. METHODS: Nineteen childhood physical activity/fitness experts completed a 3-round Delphi process. Round 1 was open-ended questions. Subsequent rounds rated statements using a 5-point Likert scale. Recommendations were sought regarding protocol inclusion, relative importance within composite scores and score interpretation. RESULTS: Delphi participant consensus was achieved for 64% (47/73) of statement topics, including a revised conceptual model, specific assessment protocols, the importance of longitudinal tracking, and the relative importance of individual protocols and composite scores. Divergent opinions remained regarding the inclusion of sleep time, assessment/ scoring of the obstacle course assessment of motor skill, and the need for an overall physical literacy classification. CONCLUSIONS: The revised CAPL model (overlapping domains of physical competence, motivation, and knowledge, encompassed by daily behavior) is appropriate for monitoring the physical literacy of children aged 8 to 12 years. Objectively measured domains (daily behavior, physical competence) have higher relative importance. The interpretation of CAPL results should be reevaluated as more data become available.

Evaluation of a screening instrument for developmental coordination disorder.

PURPOSE: To validate the Children's Self-Perceptions of Adequacy in, and Predilection for Physical Activity (CSAPPA) scale as a proxy for the BOTMP test in diagnosing DCD. METHODS: A sample of 209 children (M = 121; F = 87) consented to the BOTMP test, CSAPPA scale, Participation Questionnaire, Léger 20-meter Shuttle Run, and body fat using bioelectric impedance. Receiver Operating Characteristic (ROC) curve analysis and Kappa statistic were used to validate the CSAPPA scale as a predictor for significant clumsiness on the BOTMP test. RESULTS: Prevalence of DCD was.09 +/-.03 of both males and females, all previously undiagnosed. A positive cutoff of < 47 and < 53 for DCD on the CSAPPA scale was identified in male and females, respectively. Both gender cut-offs demonstrated significant agreement (p <.01) with a positive BOTMP test. Males' results indicated a sensitivity and specificity values of.90 (CI =.18) and.89 (CI =.22). Likewise, the female subject cutoff demonstrated high sensitivity [.88 (CI =.05)] and specificity [75 (CI =.09)]. Gender specific analysis of variance (ANOVA) indicated that students identified as clumsy were not significantly different in age or height from their peers, but demonstrated significantly (p <.01) lower self-efficacy, aerobic fitness, and had significantly (p <.01) higher relative body fat. These results held true for both genders. CONCLUSIONS: These findings are consistent with the characteristics of children with DCD. These results suggest that the CSAPPA scale is a promising instrument for use in screening children for developmental coordination disorder.

Understanding physical activity and motivations for children with developmental coordination disorder: an investigation using the theory of planned behavior.

Developmental coordination disorder (DCD) is a neurodevelopmental condition, affecting approximately 5-6% of children. Previous research has consistently found children with DCD being less physically active compared to typically-developing (TD) children; however, the psychosocial factors associated with physical activity for children with DCD are poorly understood. The purpose of this study was to examine how theory-based physical activity cognitions impacts physical activity behaviors for children with and without DCD. Participants included a sample of boys (N=61, Mage=13.25 ±.46) with DCD (n=19) and without DCD (n=42), drawn from a larger prospective cohort study. A questionnaire with psychosocial measures was first administered, and accelerometers were used to assess their physical activity behavior over the subsequent week. Findings indicate that DCD was significantly associated with lower physical activity (F(1,58)=6.51, p<.05), and poorer physical activity cognitions (F(4,56) Wilks Lambda=2.78, p<.05). Meditational analyses found attitudes (B=.23, p<.05) and subjective norms (B=.31, p<.05) partially mediating the relationship between DCD and physical activity. Overall, this study further confirms that the activity deficit that exists among boys with DCD, and that the relationship is partially mediated through some physical activity cognitions. Interventions should target the perceived approval of influential people, and the personal evaluations of physical activity for boys with motoric difficulties. These findings further emphasizes the discrepancy in physical activity that exist between boys with DCD and TD boys, and highlight the need to better understand the psychological factors related to physical activity for children with DCD.

A prospective cohort study comparing workload in children with and without developmental coordination disorder.

The purpose of this prospective cohort study was to assess how cardiorespiratory fitness (CRF) of children with probable developmental coordination disorder (DCD) changes over a period of 4.7 years relative to a group of typically developing controls. A school-based sample of children in a large region of Ontario, Canada with 75 out of a possible 92 schools consented to participate. Children enrolled in Grade 4 (mean = 9.9 years, SD = 0.35) at baseline (n = 2278) were followed over the course of 56 months. A total of eight waves of data collection were carried out throughout the study period. The short form of the Bruininks-Oseretsky test of motor proficiency was used to identify children with probable DCD and the maximal speed attained on the Léger 20-m shuttle run to measure CRF. Mixed-effects modeling was used to estimate the change over time in maximal Leger run speed for both groups adjusting for relevant covariates (e.g., gender, BMI, school, activity level, predilection for activity). Children with pDCD had consistently lower maximal run speed relative to controls. The trajectories of run speed in children with probable DCD and those without the disorder differed by gender with pDCD females demonstrating the lowest scores over time. Both genders with probable DCD showed a greater rate of decline in CRF over time relative to the controls. In conclusion, the difference in CRF between children with and without probable DCD is substantial, and it tends to increase over time. This adds to the argument suggesting that interventions intended to improve CRF may be appropriate and necessary for children with motor difficulties.

Developmental Coordination Disorder, gender, and body weight: examining the impact of participation in active play.

BACKGROUND: To examine whether differences in participation in active play (PAP) can account for gender differences in the relationship between Developmental Coordination Disorder (DCD) and body weight/fat (BMI and percentage fat) in youth. METHODS: A cross-sectional investigation of students in grades four through eight (n = 590). Height, weight (BMI), and percentage body fat using bioelectrical impedance analysis (BIA; RJL Systems, MI) were collected. Motor proficiency and physical activity levels were also evaluated. RESULTS: We found gender specific patterns in the relationship between PAP, DCD, and BMI and body fat. Among boys with DCD, greater participation in active play is associated with higher BMI and percentage body fat. For girls with the disorder, the opposite relationship is observed. CONCLUSIONS: Participation in active play moderates the association between DCD, gender and body weight. Three possible explanations for why PAP is associated with higher BMI and percentage body fat in boys with DCD are provided.

Metabolic syndrome in children with and without developmental coordination disorder.

Children with developmental coordination disorder (DCD) have higher rates of obesity compared to children with typical motor development, and, as a result may be at increased risk for developing metabolic syndrome (MetS). The purpose of this study was to determine the presence of MetS and its components among children with and without DCD. This nested case-control study classified 63 children scoring below the 16th percentile on the Movement Assessment Battery for Children (M-ABC-2) as probable DCD (pDCD), and 63 controls, all of whom scored above the 16th percentile. Metabolic syndrome was defined using the International Diabetes Federation (IDF) criteria. Eleven children met the criteria for MetS; 8 (72.3%) with pDCD and 3 (27.3%) controls (p = 0.115). Abdominal obesity was found in 39 (30.9%) of children, 29 (46.0%) with pDCD and 10 (15.9%) controls (p < 0.01). Serum triglycerides were higher in pDCD compared to controls, 91.9 mg/dl (63.1) vs. 67.7 mg/dl (33.3) in the control group, p = 0.001. Blood pressure was also significantly higher in the pDCD group, mean systolic BP (110 vs. 105 mmHg, p = 0.01) and mean diastolic BP (69 vs. 65 mmHg, p = 0.01). There were no statistically significant differences between the groups for other components of MetS. The higher prevalence of abdominal obesity and elevated triglycerides and blood pressure in children with pDCD may put them at risk of meeting all criteria of MetS earlier then their peers.

Generalized self-efficacy and performance on the 20-metre shuttle run in children.

It has been argued that motivation significantly affects the measurement of aerobic capacity when using field tests with children. In this study, the impact of generalized self-efficacy on performance (Stage Completed) in the Léger shuttle run is examined in a cohort of children (N = 2,245, 9.38 +/- 0.52 years old) in Grade 4 from 75 elementary schools. Children completed the Children's Self-perceptions of Adequacy in and Predilection for Physical Activity scale (CSAPPA) to establish levels of generalized self-efficacy toward physical activity, were measured for height and weight, and then completed the Léger Shuttle run to predict aerobic capacity. Regression analysis was used to study the impact of self-efficacy on test performance. After adjusting for age, gender, and BMI, two of the three CSAPPA factor subscales, higher perceived adequacy regarding physical activity (beta = 0.196, P < 0.001) and greater predilection to select physical over sedentary activities (beta = 0.123, P < 0.001), were independently associated with better test performance as indicated by stage completed. Together, self-efficacy accounted for 9% of the total variation in Léger shuttle run performance. A significant interaction between BMI and perceived adequacy was found (beta = -0.106, P < 0.005). Children with both high BMI scores and below average perceived adequacy had the poorest performance results. Generalized self-efficacy, as measured by the CSAPPA, is significantly related to Léger shuttle run performance. Moreover, self-efficacy influences the relationship between other known factors affecting test performance (BMI), suggesting that self-perception of ability/competence has a complex effect on test performance. These results illustrate the importance of considering psychological factors when interpreting physiologic assessments in children.

Developmental coordination disorder and cardiorespiratory fitness in children.

It is not known whether children with Developmental Coordination Disorder (DCD) have lower cardiorespiratory fitness (CRF) than children without the disorder, or whether this relationship varies by age and gender. These issues are examined using a cross-sectional assessment of children 9-14 years of age (N = 549). Participants were screened for DCD using the short form Bruininks-Oseretsky Test of Motor Proficiency (BOTMP-SF). A BOTMP-SF age-adjusted standard score at or below the 10th percentile rank on the BOTMP-SF was required to classify a diagnosis for probable DCD. CRF was determined from each participant's predicted peak-aerobic power using the Léger 20-m shuttle-run test. Children with DCD report lower CRF than children without the disorder and are more likely to be in a high-risk group (

Developmental coordination disorder and aerobic fitness: is it all in their heads or is measurement still the problem?

Developmental coordination disorder (DCD) is characterized by motor inproficiency, resulting in significant impairments in social and/or academic functioning. About 5-9% of all school-age children are affected. Previous research has shown that children with DCD have lower aerobic fitness levels than children without the disorder, although the reasons for this have not been tested in the literature. A potential explanation may lie in perceived adequacy regarding performance in physical activity. Although negative perceptions of adequacy in children with DCD likely reflect an accurate appraisal of actual physical abilities, aerobic fitness tests typically require minimal coordination skills. Children who perceive themselves to be less adequate are unlikely to persist at a task and may give up sooner on these tests of endurance. Using a large community based sample of children ages 9 through 14 (n=586), we examine whether differences in aerobic fitness (assessed by performance on a 20-m shuttle run test) between children who meet the criteria for DCD (n=44) and those who do not (n=542) is due to differences in perceived adequacy toward physical activity. Our results show that one-third of the effect of DCD on VO(2) can be attributed to differences in perceived adequacy. These results suggest that at least part of the reason children perform less well on tests of aerobic endurance is because they do not believe themselves to be as adequate as other children at physically active pursuits. The implications of this for further research are discussed.

Increased risk for coronary vascular disease in children with developmental coordination disorder.

PURPOSE: Physical activity (PA) is compromised in children and adolescents with Developmental Coordination Disorder (DCD). The purpose of this study was to test a theoretical model linking DCD with 2 factors associated with increased risk for coronary vascular disease: (1) cardio-respiratory fitness (CF), and (2) relative body fat (BF), through physical activity. METHODS: A cross-sectional design was implemented using 571 elementary school students (313 males, 258 females). Evaluation of body fat using bioelectric impedance, cardio-respiratory fitness using Léger 20-meter Shuttle Run, and physical activity level was determined using the Participation Questionnaire. The short-form version Bruininks-Oseretsky Test of Motor Proficiency was used to verify DCD. We tested to see how much of the association between DCD and factors associated with increased risk for coronary vascular disease (percentage body fat and cardio-respiratory fitness) using multivariate ordinary least squares regression analysis. RESULTS: Regression modeling demonstrated that DCD was associated with increased body fat and low cardio-respiratory fitness. Physical activity was a significant mediator in the DCD-CF relationship. Physical activity was also a mediating factor in the DCD-BF relationship, albeit to a lesser extent. CONCLUSIONS: Developmental coordination disorder is related with factors associated with increased risk for coronary vascular disease, including decreased cardio-respiratory fitness and increased body fat through the mediating influence of physical activity in children.

Developmental coordination disorder, generalized self-efficacy toward physical activity, and participation in organized and free play activities.

OBJECTIVE: To test a theoretical model linking developmental coordination disorder (DCD) to reduced physical activity (PA) through the mediating influence of generalized self-efficacy regarding PA. STUDY DESIGN: This was a cross-sectional investigation of students in grades 4 through 8 from 5 elementary schools in the Niagara region of Ontario, Canada (n=590). Motor proficiency was evaluated using the short-form Bruininks-Oseretsky Test of Motor Proficiency. Generalized self-efficacy was assessed using the Children's Self-Perceptions of Adequacy in and Predilection for Physical Activity scale, and PA levels were evaluated using a 61-item Participation Questionnaire. Structural equation modeling was used to test the influence of generalized self-efficacy on the relationship between DCD and PA. RESULTS: In this sample, 7.5% (n=44) of the children met the requirements for probable DCD. The effect of DCD on PA was mediated by generalized self-efficacy. In this model, 28% of the variance in children's PA was predicted by generalized self-efficacy and DCD. CONCLUSIONS: Our results suggest that children with DCD are less likely to be physically active and that generalized self-efficacy can account for a considerable proportion of this relationship. The implications for appropriate interventions to increase PA among children with DCD are discussed.