Habitual, Free-living Physical Activity, % Body Fat, And Motor Performance In Danish Children

Abstract

Although several studies have examined the univariate relationships among physical activity (PA), percent body fat (%BF), and motor performance (MP) in children, few have explored potential interactions among these variables. PURPOSE: The aims of this study were: a) determine the inter-relationships among PA, %BF, and MP; b) determine the combined influence of %BF and PA on MP; and c) determine the combined influence of %BF and MP on PA in 6- to 8-year-old Danish children. METHODS: PA, %BF, and MP were measured in 498 children (265 boys, 233 girls) during baseline data collection of the Copenhagen School-Child Intervention Study. PA was assessed over 4 days (2 weekdays, 2 weekend days) with the Actigraph accelerometer. %BF was calculated using the Slaughter equation from skinfold thicknesses. The KTK with the addition of a throwing accuracy test was used to assess MP. Correlations were used to examine associations among PA, %BF, and MP. Using ANOVA, MP was compared across four groups created by cross tabulation of %BF and PA using median split (Low %BF/High PA, Low %BF/Low PA, High %BF/High PA, and High %BF/Low PA). Using ANOVA, PA was compared across four groups created by cross tabulation of %BF and MP using median split (Low %BF/High MP, Low %BF/Low MP, High %BF/High MP, and High %BF/Low MP). RESULTS: PA was not associated with %BF (r = -.06, boys; r =.01, girls), but was significantly associated with MP (r =.21, boys; r =.14, girls, p <.05). The strongest relationships existed between %BF and MP, and remained after controlling for age and PA (r = -.36, boys; r =-.25, girls, p <.001). In both sexes, Low %BF/High PA had significantly higher (p≤.001) MP scores compared to High %BF/Low PA, and within the High %BF groups MP was significantly higher (p≤.001) in the High PA versus Low PA group. When comparing PA by the combination of %BF and MP, boys in the Low %BF/High MP had significantly higher (p<.05) PA than both the Low %BF/Low MP and High %BF/Low MP groups. In girls, PA was highest in the High %BF/High MP group and only significantly different (p<.05) from the Low %BF/Low MP group. CONCLUSION: This study highlights the complex interrelationships among PA, %BF, and MP in children. This sample is comprised of relatively lean children; stronger associations may exist in children with higher %BF. Funded by the Danish Heart Association & Ministry of Health