KMAN Publication Inc. (KMANPUB) Health Nexus In Press 2026 10 01 Effects of a 12-Week School-Based Physical Education and Nutrition Education Intervention on Obesity Indices and Cardiorespiratory Fitness in Upper Elementary School Boys: A Quasi-Experimental Study Effects of a 12-Week School-Based Physical Education and Nutrition Education Intervention on Obesity Indices and Cardiorespiratory Fitness in Upper Elementary School Boys: A Quasi-Experimental Study 1 10 10.61838/ EN Journal Article 2026 03 15 <p>Childhood overweight, obesity, and declining physical activity are major public-health concerns, and schools provide a practical setting for preventive interventions. This quasi-experimental study examined the effects of a 12-week integrated school-based physical education, nutrition education, and energy-intake management program on body-composition indices and cardiorespiratory fitness in upper elementary school boys in District 5 of Tehran, Iran. One hundred eligible boys were selected by multistage cluster sampling and allocated to an intervention group (n = 50) or a control group (n = 50). The intervention group participated in a structured physical education program twice weekly for 12 weeks (45 min/session) and received six nutrition-education sessions with guidance designed to reduce habitual energy intake by approximately 200-300 kcal/day without severe dietary restriction. The control group continued usual school activities. Body mass, body mass index (BMI), body-fat percentage, waist circumference, hip circumference, waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), three-site skinfold thickness, 20-m shuttle-run performance, and estimated maximal oxygen uptake (VO₂max) were assessed before and after the intervention. Data were analyzed using paired-samples t tests, independent-samples t tests, and analysis of covariance controlling for pretest values. After 12 weeks, the intervention group showed meaningful reductions in body mass (-6.0%), BMI (-6.8%), body-fat percentage (-15.7%), waist circumference (-7.4%), WHR (-5.6%), WHtR (-7.4%), and total skinfold thickness (-19.8%). Cardiorespiratory-fitness outcomes also improved, with increases in 20-m shuttle-run stages (+40.3%), shuttle-run laps (+45.1%), and estimated VO₂max (+18.7%). ANCOVA confirmed significant between-group differences for all outcomes, with the largest effects for VO₂max (partial η² = .41), 20-m shuttle-run performance (partial η² = .39), total skinfold thickness (partial η² = .34), and body-fat percentage (partial η² = .31). The findings indicate that combining school-based physical education with nutrition education and moderate energy-intake management can improve obesity-related indices and cardiorespiratory fitness in upper elementary school boys. Such integrated programs may represent a feasible and low-cost strategy for child-obesity prevention and health promotion in school settings.</p> https://www.journals.kmanpub.com/index.php/Health-Nexus/article/download/5645/11274