Associations of Muscular Fitness and Body Composition in Children

Purpose: To examine the associations between muscular fitness (MF) and body composition. Method: MF was assessed with three tests of FitnessGram test battery. Total body fat percentage (BF%), abdominal fat percentage (AF%) and fat-free mass (FFM) were measured by dual-energy X-ray absorptiometry (DXA). The IOTF body mass index (BMI) cut-offs were used to define healthy weight, overweight, and obesity. Results: MF was inversely associated with BF% and AF%. The children in the moderate and high MF groups had significantly lower BF% and AF% compared with the children in the low MF group within the same BMI category. After adjusting for cardiorespiratory fitness (CRF), BMI and sex, the differences between the MF groups were significant for BF% but not for AF%. Conclusion: There were significant inverse associations between MF and DXA--measured adiposity. Within the same BMI category, total and abdominal adiposity were lower in children with moderate or high MF than in children with low MF.