The study looked at 24 children who had been diagnosed with ADHD (mean age 9.8 years, and 23 of the 24 were boys). Each child took part in two sessions in a mixed order. In one session they did moderate aerobic exercise. In the other they watched a video. After each session the children did tasks that measure inhibitory control, which is the ability to hold back an automatic response and stay accurate.
The children did better after exercise than after the video. They were more accurate across the different tasks and time points (90.5% correct after exercise versus 84.1% after the video). Their response times were also steadier on the easier trials measured 30 minutes later (129.8 ms of variation versus 142.2 ms). A brain signal tied to attention, called the P3 response, was faster after exercise at the 30-minute mark (426.9 ms versus 517.9 ms).
These gains did not last. The benefits held for only about 30 to 40 minutes after the exercise stopped. The study was small, with just 24 children, and nearly all of them were boys, so the findings come from a narrow group.
Source: Hsieh S, Yu C, Chueh T, et al.. The Sustained Effects Of Acute Aerobic Exercise On Inhibitory Control In Children With ADHD. Medicine & Science in Sports & Exercise (2020). doi:10.1249/01.mss.0000684708.01952.2b