Evaluation of the reliability of processes and results of a TGfU-based handball intervention in under-11 players

This study investigated the development, validation, and evaluation of an extracurricular handball program based on Teaching Games for Understanding (TGfU) for students aged 8–11 years (U-11 teams), focusing on tactical-technical learning. A quasi-experimental field intervention (uncontrolled pre- and post-test) initially enrolled 30 students, with 20 ultimately analyzed (8 girls, 12 boys) according to the inclusion criteria. The program comprised 14 didactic units (50-min sessions), validated by an international TGfU expert. Unlike studies that merely infer methodological application, this research objectively monitored procedural fidelity and intervention integrity using the SIATE framework. Tactical-technical learning was assessed through GPAI, measuring Decision-Making (DMI), Skill Execution (SEI), Game Performance (GP), and Game Involvement (GI). SIATE analysis indicated high fidelity to TGfU, with over 80% of time dedicated to problem-solving through modified games and authentic opposition. Significant improvements ( p  < 0.05) in DMI were observed in both groups. GP also improved, reaching statistical significance exclusively in the boys’ group. Although many boys descriptively had previous experience in similar invasion sports, such as futsal, this variable was not statistically modelled, preventing causal inferences regarding cross-sport transfer. No significant differences were found in SEI, with reductions observed in two participants, suggesting that technical stabilization may require more time than tactical awareness. A reduction in GI indicated a shift toward higher-quality actions, replacing “anarchic play” with efficient decisions. TGfU-based instruction was associated with pre-post improvements in decision-making and tactical-technical development. SIATE strengthened methodological rigor and ecological fidelity, emphasizing learners and the game's internal logic. We recommend the continued use of game-based approaches are recommended to promote meaningful learning in youth teams.