This review looked at children and teenagers with ADHD, aged 6 to 17. It pulled together 12 studies with 375 young people, and 11 of those studies (275 young people) were combined in the main analysis. Most of the participants were 13 or younger, so the results say more about children than about teenagers.
The studies tested what happened right after one session of moderate-to-vigorous physical activity, such as brisk exercise. On tasks that asked less of thinking and self-control, the children did a little better afterward (effect size g = 0.32, likely range 0.123 to 0.517). On harder thinking tasks the gain was also small (g = 0.25, likely range 0.13 to 0.371). Because both kinds of tasks improved by about the same small amount, the boost seemed general rather than aimed at one skill.
The authors treat a single 15 to 30 minute bout of activity as a possible add-on to other treatment that may briefly help thinking, not a replacement for it. They also flag weak spots. Only three studies included adolescents. Only one study hid who got which condition, no study used blinded raters, and most used a design where an earlier session could carry over and affect a later one.
Source: Ting‐Yu Chueh, Shu‐Shih Hsieh, Yu-Jung Tsai, et al.. Effects of a single bout of moderate-to-vigorous physical activity on executive functions in children with attention-deficit/hyperactivity disorder: A systematic review and meta-analysis. Psychology of sport and exercise (2021). doi:10.1016/j.psychsport.2021.102097