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 (≥. 10. min). 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 medium-to-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.