Length of moderate-to-vigorous physical activity bouts and cardio-metabolic risk factors in elementary school children

Background. Accumulating moderate-to-vigorous physical activity (MVPA) in bouts of 10 min is associated with improved cardio-metabolic risk factors (CMRF) in adults. Purpose. To assess the association between the lengths of MVPA bouts and CMRF in elementary school age children. Methods. The sample included 396, 2nd and 3rd grade students from eastern Kansas (182 boys, 214 girls; age 7.6 +/- 0.6 years; Body Mass Index Percentile [BMI%ile]: 61.6 +/- 9.3) in the fall of 2011. Analyses were conducted in 2014. MVPA bouts were defined as sporadic (<5 min), short (5-<10 min) or medium-to-long (>= 10min). Latent profile analysis was used to identify distinct subgroups (classes) based on the composition of MVPA bouts. Bayesian probability-based Wald chi-square test was used to compare CMRF between classes controlling for age, sex, BMI%ile, and total moderate and total vigorous PA. Results. Three classes of accumulated physical activity were identified: A (n = 78); 97% sporadic 2%, short, 1% medium-to-long bouts; B (n = 174); 93% sporadic, 5% short, 2% medium-to-long; C (n = 144); and 86% sporadic, 9% short, 5% medium-to-long bouts. Class C had significantly lower BMI%ile (57.3 +/- 2.3 (SE)), waist circumference (WC; 55.8 +/- 0.5 cm) compared with Class A (BMI%ile = 70.9 +/- 0.5, p < 0.01.030, WC = 61.0 +/- 1.0 cm, p = 0. < 0.01). Class B had significantly lower WC (56.6 +/- 0.6 cm), p < 0.01 than Class A. No significant differences between classes were shown in other outcomes. Conclusion. Children who accumulated MVPA with a higher percentage of short (5-<10 min) and mediumto-long bouts (>= 10 min) had lower BMI%ile, and WC compared with children who accumulated MVPA with a lower percentage short and medium-to-long bouts. (C) 2015 Elsevier Inc. All rights reserved.