Exercise Helps ADHD on a Narrow Outcome and a Short Clock

What the research found

Twenty minutes of exercise, arranged as intervals: bursts of effort lasting anywhere from fifteen seconds to four minutes, each followed by a recovery period of the same length at forty to fifty percent of the child’s maximum heart rate. That protocol, and a gentler one at sixty-five to seventy-five percent of maximum heart rate sustained for twenty to thirty minutes, is what a 2022 review of physical exercise and ADHD in the journal Biomedical Journal recommends for children. Yuan-Shuo Chan of National Taipei University of Education wrote it with Jia-Tzer Jang and Chin-Shan Ho of National Taiwan Sport University. Maximum heart rate throughout is the standard rough estimate, 220 minus the child’s age.

The strongest pooled result the review assembles concerns executive function, the set of skills a mind uses to hold a goal in view and steer itself towards it. A meta-analysis that screened 314 studies and retained 31 found that exercise interventions improved executive function in children and adolescents with ADHD, with a standardised effect of 0.611. Two components accounted for most of that: inhibitory control, the capacity to stop a response already under way, at 0.761, and cognitive flexibility, the capacity to switch between rules, at 0.780.

How long the effect persists was measured directly. Children with ADHD given a single bout of moderate-intensity aerobic exercise showed improved response accuracy and conflict detection for sixty minutes afterwards, whether the task in front of them was easy or hard. In a separate comparison, children aged eight to twelve who exercised at moderate intensity for twenty minutes outperformed children with ADHD who spent the same twenty minutes watching videos. An electroencephalography study of inhibitory control found the improvement was greatest in the children who arrived with the least of it.

The review credits its executive function figures to two meta-analyses, one of them the 2020 analysis by Vysniauske and colleagues in the Journal of Attention Disorders. The World Federation of ADHD’s consensus statement drew on that same paper for a different outcome, and there the moderate reduction in ADHD symptoms across ten studies of 300 children did not survive adjustment for publication bias. A 2021 network meta-analysis of 83 studies and 4,996 participants ranked exercise training first for inattention among fourteen non-drug treatments, though it reported neither an effect size for that ranking nor any adjustment for publication bias. Performance on cognitive tasks responds to exercise consistently across the literature Chan and colleagues assemble; the rating scales that define an ADHD diagnosis are the contested ground.

What it means for you and your child

The dose is modest and unusually well specified. Twenty minutes, done as alternating effort and rest rather than a steady jog, is the form recommended, and intensity rather than duration is what the physiological account rests on. That account, in which moderate to high intensity raises lactate, brain-derived neurotrophic factor and blood flow to the brain, is assembled from other researchers’ work rather than tested here.

If one bout of moderate aerobic exercise improves inhibitory control for an hour, twenty minutes of hard play before the homework hour is doing different work from twenty minutes after it. A school that schedules physical education at the end of the day is spending that hour on the journey home.

Children with ADHD lose patience with repetitive drills, and the review is candid that adherence is the more realistic obstacle. The sessions that held their participants built game elements into the exercise and ran on steady encouragement, which is why the interval format is recommended over the treadmill in the first place.

Not everything in the review comes out this well. Two meta-analyses of meditation and mindfulness for ADHD reached no conclusion at all, one because its four studies of 83 children were too few and too vulnerable to bias, the other because most of its sixteen studies ran without a control group. Where a child has Tourette syndrome alongside ADHD, intensity cuts both ways: low-intensity aerobic exercise may reduce tics while high-intensity exercise may increase them, so the interval protocol is not automatically the right choice.

This is a narrative review rather than a systematic one. No search protocol is stated, the authors include a pilot study of their own among the evidence they weigh, and they describe the state of the field as preliminary and exercise as an adjunct to treatment rather than a substitute for it. What survives that honesty is narrow and worth having. A single ordinary session of twenty minutes, at an intensity that leaves a child breathing hard, was followed in one study of children with ADHD by an hour in which their command of their own attention measurably improved. An hour of steadier attention, measured once in one group of children, is the whole of what the strongest evidence here describes.