26th Jan 2024

Introduction: Several studies have reported significant improvements in cardiorespiratory fitness (CRF) in children with high-intensity exercise. However, most research protocols focus on cycling and running. These protocols are not applicable for practical purposes in children. The aim of the study was assess the effect of an 11-week intervention using games protocols of two different intensities (high-intensity games and moderate-intensity games) on CRF in children. Method: Quasi-experimental design, participated 48 schoolchildren aged between 9 to 10 years (9.48 ± 0.5 years). Children were randomized into two groups: high-intensity games (HIG) and moderate-intensity games (MIG). HIG group used relays race and small- sided games; >75% of maximum heart rate (HRmax). MIG group used cooperative and dynamics continued games; 60% – 74% HRmax. Both groups had two sessions per week for 11 weeks during physical education (PE) classes. Before and after the interventions, participants measured with the CRF test (20-meter shuttle run test). Repeated-measure analysis 2 × 2 was used to determine the main effects and the interaction effects between groups over time (pre and post-test) and the effect size (ES) was calculated using Cohen’s d test. Results: Significant time × group interaction was observed for CRF with a moderate ES (F = 4.879, P = 0.032; ES = 0.6), between HIG and MIG, therefore, the HIG protocol significantly increased the CRF. Conclusion: This study demonstrates that an 11-week HIG program, applied during PE classes, is more effective than MIG in the improvement of the CRF in children.