Individual responsiveness to a school‐based karate intervention: An ancillary analysis of a randomized controlled trial

INTRODUCTION: School‐based sport interventions have shown beneficial effects on psychosocial functioning and academic performance in children. However, the inter‐individual variability in response to these types of interventions remains unclear. We aimed to determine which children benefit most from a school‐based sport intervention. METHODS: This is an ancillary analysis of a randomized controlled trial assessing the effects of a 1‐year school‐based karate intervention (versus “traditional” physical education lessons) in children (7–8 years) from twenty schools across five European countries. Outcomes included psychosocial functioning (Strengths and Difficulties Questionnaire [SDQ] for parents) and academic performance (grade point average). Only participants of the intervention group were included in the present ancillary analysis, and were categorized as responders or non‐responders for the analyzed outcomes attending to whether improvements surpassed a minimal clinically important difference. RESULTS: About 388 children (187 girls) from the intervention group completed the study, of which 17% and 46% were considered responders for SDQ and academic performance, respectively. Responders for the SDQ presented higher SDQ scores (i.e., higher psychosocial difficulties) at baseline than non‐responders (p < 0.001). Responders for academic performance were mostly males (p = 0.017), with an older age (p = 0.030), and with worse academic performance (p < 0.001) at baseline compared with non‐responders, and tended to present higher SDQ scores (p = 0.055). Responders for one outcome obtained greater benefits from the intervention on the other outcome (e.g., responders for SDQ improved academic performance [p < 0.001] compared with non‐responders). CONCLUSIONS: A school‐based sport intervention (karate) seems particularly effective for children with psychosocial difficulties and low academic performance.