Children who were fitter in their youth are less likely to develop depression as adults, according to a landmark Australian study tracking participants for more than three decades.

Researchers from the Menzies Institute and Adelaide University followed over 1,000 people from a national cohort first surveyed in 1985, when they were aged 7 to 15. Fitness was measured with a 1.6-kilometre run and a standing long jump.

Three decades later, participants underwent a World Health Organization diagnostic interview. Those who had run faster as children showed about a 15 percent lower relative risk of lifetime depression.

Cardiorespiratory fitness showed the strongest and most consistent link. The protective effect was greatest five to ten years after testing and was stronger among females.

Lead author Dr Kylie Smith cautioned that fitness is only one piece of the puzzle. ‘We cannot say a lack of fitness during childhood causes depression in adults,’ she said.

The findings, published in the Journal of Affective Disorders, add to evidence that keeping children active pays mental-health dividends for decades.