Digital activities that involve learning, creativity, problem-solving, or other forms of active mental engagement could potentially help explain the association observed in the study. “We should not regard screen time solely as harmful but seek balance between physical activity and screen time that promotes active thinking,” Jalanko summarizes. The relationship between physical activity and cognition was more complicated. Among girls, greater amounts of light intensity physical activity since childhood were associated with better working memory during adolescence. Among boys, greater participation in guided physical activity from childhood through adolescence was linked to better working memory.
The researchers also found an unexpected pattern involving unsupervised exercise. Lower levels of self-reported unsupervised physical activity were associated with better cognitive processing in adolescence. By contrast, physical activity and sedentary time measured using a device that tracked heart rate and movement were not associated with cognitive processing. One possible explanation is that these sensors can measure movement and physiological activity but cannot determine exactly what a person is doing during periods of activity or inactivity. The findings have been published in the journal Pediatric Exercise Science.