UNLABELLED: Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental condition in children, characterized by inattention, hyperactivity, and impulsivity. Recent studies have investigated the potential role of physical exercise as a complementary intervention to traditional ADHD treatments. This study aimed to compare the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on ADHD symptoms and behavioral inhibition in children diagnosed with ADHD. In a randomized controlled trial, 60 male participants aged 7-10 years were allocated into three groups: control, MICT, and HIIT. The intervention lasted 12 weeks, with the MICT group performing 20 min of running at 70-75% of their individual VO2 max and the HIIT group performing alternating intervals of running at 100% and 50% of their VO2 max for 1 min each. The control group received no exercise intervention. Cognitive and symptomatic assessments were conducted using the Children's Symptom Questionnaire (CIS-4) and go/no-go tasks before and 48 h post-intervention. Both MICT and HIIT demonstrated significant improvements in behavioral components, including attention deficit, hyperactivity, and impulsivity (all P <
0.0001). HIIT showed superior effects on attention deficit compared to MICT (P = 0.008). Both HIIT (P <
0.0001) and MICT (P = 0.028) improved correct responses (CR) in the Go task compared to the control group. HIIT also outperformed the control group in erroneous responses (ER) (P = 0.022) and correct reaction time (P = 0.027) in the Go task. In the No-Go task, HIIT showed superiority over the control group in both CR (P = 0.013) and ER components. CONCLUSION: This study highlights the comparative efficacy of MICT and HIIT as nonpharmacological interventions for children with ADHD. HIIT, in particular, demonstrated superior benefits for attention deficits, suggesting its potential as a targeted adjunctive treatment. These findings may inform the development of exercise programs to enhance the quality of life and daily functioning of children with ADHD. WHAT IS KNOWN: • Physical exercise has been explored as a complementary intervention for ADHD, with evidence suggesting its potential to improve symptoms such as inattention, hyperactivity, and impulsivity. • Moderate-intensity continuous training (MICT) has shown positive effects on cognitive and behavioral outcomes in children with ADHD. WHAT IS NEW: • High-intensity interval training (HIIT) demonstrated superior benefits over MICT in improving attention deficits in children with ADHD. • Both HIIT and MICT significantly improved behavioral inhibition, with HIIT showing additional advantages in reducing erroneous responses and enhancing reaction times in cognitive tasks.