This paper is a narrative review, not a new study. It covers exercise research in children, adolescents and adults with ADHD. It does not say how studies were found or how many were reviewed, and it reports no pooled numbers.
The authors judge the strongest evidence to be for a single bout of moderate aerobic exercise in children with ADHD. Most of these studies found better performance on thinking and self-control tasks afterward, with effects ranging from small to large. Most compared exercise with an easy, low-effort activity such as watching a video.
Findings in adults were thinner. In one small study, young adults with ADHD improved on only one task after moderate exercise (10 adults with ADHD). Healthy peers improved on every task. This study had no non-exercise comparison.
Almost all longer exercise programs found some gains in symptoms, thinking skills, schoolwork or motor skills. In a large trial of children with ADHD (112 children), medication did better than exercise on most measures. The authors note exercise was only the comparison condition there.
The authors urge caution. Many longer studies were small, lacked random assignment or blinding, or had no fair comparison group. Trials with an active comparison did not show exercise clearly beating other activities. Only two of the single-bout studies accounted for medication.
The paper also suggests exercise might help borderline personality disorder, but no exercise studies in that condition exist.
Source: Aylin Mehren, Markus Reichert, David Coghill, et al.. Physical exercise in attention deficit hyperactivity disorder – evidence and implications for the treatment of borderline personality disorder. Borderline Personality Disorder and Emotion Dysregulation (2020). doi:10.1186/s40479-019-0115-2