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Motor coordination in children: the associations with body composition, sedentary behaviour and academic achievement

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Resumo:	Introduction: This thesis focuses on the role of motor coordination in children’s healthrelated behaviours and cognitive outcomes. Therefore, this study explores the relationships between motor coordination (MC) and body composition, sedentary behaviour (SB) and academic achievement (AA) in elementary school children. This work presents four papers in the body of the thesis and two papers in the annexes section as an integrated part of the PhD process. The specific objectives were: to evaluate the relationship between objectively measured SB and MC in Portuguese children (aged 9-10 years), accounting for physical activity (PA), accelerometer wear time, waist-to-height ratio, and mother’s education level (PAPER I); to quantify maternal misclassification of child weight status in a sample of Portuguese children aged 9 to 12 years, according to gender, family income, maternal weight status, education level and age (PAPER II); to determine the ability (sensibility and specificity) of different measures of adiposity (body mass index, waist circumference, body fat percentage and waist-to-height ratio) to discriminate between low/high motor coordination in a sample of children aged 9–12 years (PAPER III); to evaluate the relationship between gross MC and AA in Portuguese children aged 9-12 years, accounting for cardiorespiratory fitness, body mass index, and socioeconomic status (PAPER IV). Methods: Data for this exploratory cross-sectional school-based study are derived from the Bracara Study (2009/2010). The sample comprised 596 participants (281 girls) aged 9-to 12 years from 13 urban public elementary schools (4th grade) in the north of Portugal. MC was assessed with Körperkoordination Test für Kinder (KTK). PA and SB were measured by accelerometry (Actigraph GT1M). Height, weight and waist circumference were measured with standardized protocols and instruments. Body fat percentage was estimated by a bioelectric impedance digital scale (Tanita TBF-300). Cardiorespiratory fitness was assessed with the Fitnessgram battery. The 4th grade national exams were used as a measure of AA. Parents or guardians were also invited to participate through socio-biographic, PA and other health-related behaviour questionnaires. Results: In paper I, a receiver operating characteristic (ROC) analysis showed that sedentary time significantly discriminated between children with low MC and high MC, with a best trade off between sensitivity and specificity being achieved at ≥77.29% and ≥76.48% for girls and boys respectively (p<0.05 for both). In both genders, the low sedentary group had significantly higher odds of having good MC than the higher sedentary group, independent of PA, accelerometer wear time, waist-to-height ratio, and mother’s education level (p<0.05 for both). In paper II, the prevalence of underweight, overweight, and obesity in children were 4.6%, 25.5%, and 6.4%, respectively. 65.2% of underweight and 61.6% of overweight/obese children’s were misclassified by their mothers. For the majority of variables presented, the values of agreement were fair (k ranged 0.257 to 0.486), but were statistically significant. Significant differences in the percentages of mothers who correctly classified their children’s weight status were only found among the most educated in the overweight/obese group and among the normal weight mothers in the underweight group. In paper III, ROC curve analysis showed that all measures of adiposity performed well on average in identifying low MC, as indicated by the area under the curve greater than 0.6. The ROC performance of body fat percentage showed a slightly better discriminatory accuracy than body mass index, waist circumference and waist-to-height ratio in predicting low MC in girls. In boys, the ROC performance of waist circumference showed a slightly better discriminatory accuracy than body mass index, body fat percentage and waist-to-height ratio in predicting low MC. After adjustments, logistic regression analyses showed that body mass index, waist circumference, body fat percentage and waist-to-height ratio were positively and significantly associated with MC in both sexes, with the exception of waist-to-height ratio in girls. In paper IV, 51.6% of the sample exhibited MC disorders or MC insufficiency and none of the participants showed very good MC. In both genders, children with insufficient MC or MC disorders exhibited a higher probability of having low AA, compared with those with normal or good MC (p<0.05 for trend for both) after adjusting for cardiorespiratory fitness, body mass index and socioeconomic status. Conclusions: Adequate levels of MC in children have essential importance since it were found to be positive related with health-related behaviours and cognitive outcomes. Our findings suggest that PA levels per se may not overcome the deleterious influence of high levels of SB on MC. Our data stress the importance of discouraging SB among children to improve MC (paper I). Many mothers do not properly recognize their children’s weight status and frequently underestimate their children’s body size (paper II). Body fat percentage and waist circumference showed a slightly better discriminatory accuracy in predicting low MC, for girls and for boys, respectively (paper III). Children of both genders with lower MC had higher odds of having low AA, after adjusting for potential confounding factors (paper IV).
Autores principais:	Lopes, Luís Carlos Oliveira
Assunto:	Motor coordination Sedentary behaviour Physical activity Accelerometry Parental perceptions Body composition Academic achievement Children Coordenação motora Comportamento sedentário Actividade física Acelerometria Percepções parentais Composição corporal Desempenho académico e crianças
Ano:	2013
País:	Portugal
Tipo de documento:	tese de doutoramento
Tipo de acesso:	acesso aberto
Instituição associada:	Universidade do Minho
Idioma:	inglês
Origem:	RepositóriUM - Universidade do Minho