Tracking the health of Puerto Rican youth through their physical activity, fitness, nutrition and self-efficacy.

Objectives: Physical activity, fitness and nutrition influence health trajectories from childhood to adulthood and are linked to the risk of chronic diseases. Despite the urgency of prevention, there is a lack of longitudinal data about these health indicators among children in Puerto Rico. This 3-year study (2013-2016) followed 46 children from ages 7 to 9 years to assess their physical activity, fitness, nutrition and self-efficacy over time, and to explore the interrelationships among these indicators. Methods: Physical activity was measured using accelerometers, fitness via the FitnessGram assessment protocol, nutrition through 3-day dietary recall and self-efficacy with a questionnaire. Statistical analyses included repeated measures of analysis of variance, logistic regression and Spearman's correlations. Results: Throughout the study, most participants failed to meet the physical activity guidelines for Americans, with girls being consistently less active and having higher percentages of body fat than boys. Fitness levels declined over time, particularly muscular strength and endurance. Self-efficacy was positively associated with muscular fitness and body composition. Despite caloric intake falling within general age-appropriate recommendations, the low levels of physical activity suggest there may be an imbalance between energy intake and expenditure. Conclusions: Early sex disparities in physical activity and fitness, coupled with low self-efficacy and high levels of sedentary time, underscore the urgent need for public health initiatives and school-based interventions that promote active lifestyles, improve nutrition and build self-efficacy, especially among girls. Schools are uniquely positioned to implement evidence-based strategies that can foster healthier behaviors and reduce long-term health risks among youth.