This study will examine whether a game-based HIIT program can improve the executive function of children with ADHD, compared with a traditional structured aerobic exercise program and a non-treatment control group. 

Attention-deficit/hyperactivity disorder (ADHD) is a common developmental disorder in childhood, with a 5%-6% worldwide prevalence. Children with ADHD often demonstrate impaired executive function, which is closely related to the development of the commonly observed behavioral problems such as inattention, impaired inhibition, and hyperactivity. Although a number of methods have been proposed to treat ADHD, physical activity is regarded as one of the most effective ways to manage ADHD without the adverse side effects often associated with pharmacological interventions. Compared with traditional structured exercise such as running or cycling, game-based activities may more closely resemble the habitual physical activity patterns of children. Limited studies have suggested that game-based structured aerobic exercise program may benefit the executive function of children with ADHD. Recently, high-intensity interval training (HIIT) has emerged as a feasible and efficacious strategy for increasing physical health outcomes and cognitive function, including executive function, in healthy young people. However, research has yet to investigate whether the executive function of children with ADHD can be effectively enhanced through HIIT. Additionally, if the demands of HIIT could be embedded in a game-based activity, children may find it more acceptable and enjoyable. This study will examine whether a game-based HIIT program can improve the executive function of children with ADHD, compared with a traditional structured aerobic exercise program and a non-treatment control group. Additionally, the possible mechanism behind these beneficial effects will be explored through a non-invasive measurement based on functional near-infrared spectroscopy (fNIRS). A total of 42 children with ADHD will be recruited to participate in this three-arm school-based randomized controlled trial. A 12-week specially designed game-based HIIT (GameHIIT) program and a traditional game-based structured aerobic exercise (GameSAE) program will be delivered to those children randomly assigned to these two intervention groups, while the children in the control group will maintain their regular physical activity over the same period. A number of outcome measures including executive function, cerebral hemodynamic response, physical activity, physical fitness, and enjoyment and adherence to the intervention will be assessed for both groups at baseline (T0), immediately after the intervention period (T1), and after the follow-up period (T2). If, as hypothesized, GameHIIT program improves outcomes for children with ADHD, the present research will inform the development of targeted exercise programs that can be more broadly used with this particular population.