Simply moving more throughout the day may be linked to better mental health as young people enter adolescence. A large US study found that 11- and 12-year-olds who accumulated more daily steps tended to experience fewer symptoms of anxiety, low mood and behavioural problems a year later, suggesting that ordinary physical activity could play a meaningful role during this important stage of development.

The study, led by King’s College London’s Institute of Psychiatry, Psychology & Neuroscience in collaboration with the University of Massachusetts Amherst, followed 5,515 adolescents taking part in the US Adolescent Brain Cognitive Development Study. Participants wore Fitbit devices for three weeks at around age 11 or 12, giving researchers an objective measure of their daily activity.

A year later, researchers assessed the adolescents’ mental health using the Child Behaviour Checklist, which measures symptoms including anxiety, low mood and behavioural problems. They found a clear pattern: the more steps young people took, the fewer mental health symptoms they reported. Those walking fewer than 5,000 steps a day had the most symptoms, while those averaging about 8,000 had fewer and those reaching 12,000 or more had the fewest.

Importantly, the benefits did not appear to level off within the range studied. Even relatively modest increases in activity were associated with better outcomes. An additional 1,000 to 2,000 daily steps, regardless of a young person’s starting point, were linked to better mental health and differences in brain structure.

Adolescents with higher step counts also had slightly thicker brain tissue in two regions involved in movement and emotional regulation. Researchers said these differences appeared to explain part of the association between physical activity and better mental health, although the changes were small. Daily step counts were not associated with academic performance.

“This study gives us some of the clearest evidence yet that even an everyday, low-cost, accessible measure of physical activity like daily step count is tied to how adolescent brains and mental health develop,” said senior author Dr Divyangana Rakesh of King’s College London. Lead author Qingyang Li added that the findings offer preliminary clues about which parts of the brain may be involved.

Dr Amanda Paluch, Associate Professor of Kinesiology at the University of Massachusetts Amherst, said the findings show young people do not have to become elite athletes to benefit potentially. Everyday activities such as walking to school, active play and sports can all add steps. “It is not an all-or-nothing situation,” she said, emphasising the importance of finding enjoyable and sustainable ways for adolescents to move more.

The researchers cautioned that the study was observational, meaning it cannot prove that taking more steps directly improves mental health. Young people with better mental health may be more inclined to stay active. Still, the association remained after researchers accounted for earlier mental health problems, and the use of wearable devices provided a more objective picture of activity than self-reported questionnaires. The findings add to growing evidence that ordinary movement woven into daily life may have an important role in adolescent well-being.

More information: Qingyang Li et al, Physical Activity and Adolescent Brain Structure, Mental Health, and Academic Outcomes, JAMA Network Open. DOI: 10.1001/jamanetworkopen.2026.36973

Journal information: JAMA Network Open Provided by King’s College London