Motor competence and cardiorespiratory fitness have greater influence on body fatness than physical activity across time.

We investigated the longitudinal associations among physical activity (PA), motor competence (MC), cardiorespiratory fitness (VO2peak ), and body fatness across 7 years, and also analyzed the possible mediation effects of PA, MC, and VO2peak on the relationships with body fatness. This was a seven-year longitudinal study with three measuring points (mean ages [in years] and respective sample size: 6.75±0.37, n=696; 9.59±1.07, n=617; 13.35±0.34, n=513). PA (moderate-to-vigorous PA-MVPA and vigorous PA-VPA) was monitored using accelerometers. MC was assessed by the "Körperkoordinationstest für Kinder-KTK" test battery. VO2peak was evaluated using a continuous running protocol until exhaustion. Body fatness was determined by the sum of four skinfolds. Structural equation modeling was performed to evaluate the longitudinal associations among PA, MC, VO2peak, and body fatness and the potential mediation effects of PA, MC, and VO2peak . All coefficients presented were standardized (z-scores). MC and VO2peak directly influenced the development of body fatness, and VO2peak mediated the associations between MVPA, VPA, MC, and body fatness. MC also mediated the associations between MVPA, VPA, and body fatness. In addition, VO2peak had the largest total association with body fatness (β=-0.431; P<.05), followed by MC (β=-0.369; P<.05) and VPA (β=-0.112; P<.05). As PA, MC, and VO2peak exhibited longitudinal association with body fatness, it seems logical that interventions should strive to promote the development of fitness and MC through developmentally appropriate physical activities, as the synergistic interactions of all three variables impacted body fatness.