Teenagers who take more steps each day tend to have better mental health, according to a large study tracking 5,515 adolescents in the United States.

The research, led by King's College London with the University of Massachusetts Amherst, used Fitbit devices to measure activity in 11- and 12-year-olds over three weeks. A year later, the team assessed mental health using a standard questionnaire completed by the teens and their parents.

Even 1,000 to 2,000 extra daily steps were associated with better brain structure and mental health outcomes, said Dr Amanda Paluch of UMass Amherst.

The study, published in JAMA Network Open, is observational, so it cannot prove that walking more directly improves mental health. It is possible that teens with fewer problems were simply more active to begin with.

Still, the researchers say the message is encouraging: adolescents do not need to be elite athletes to benefit — everyday movement like walking to school counts.