Substitution of physical activity for sedentary behaviour contributes to executive function improvement among young adults: a longitudinal study.

Background: Sedentary lifestyles may affect cognitive capacities which are essential for daily tasks. There is a lack of research on the effects of replacing sedentary behaviour with physical activity on executive function, as well as the dose-response relationship between physical activity and executive function among young adults, underscoring the critical need for prompt investigation.

Methods: Employing a longitudinal experimental design, the study conducted two assessments (baseline and at three months) on a cohort of participants. A total of 78 young adults with a mean age of 25 years old were recruited for the study. Physical activity and sedentary behaviour were measured using accelerometer, which provided objective data on the intensity and duration of the participants' daily activity. Executive function was measured using the Trail Making Test (TMT). An isotemporal substitution model was employed to analyze the effects of replacing sedentary time with physical activity of different intensities. Additionally, mixed-effect models were used to explore the dose-response relationships between physical activity, sedentary behaviour, and executive function.

Results: The reallocation of 30 min of daily time from sedentary behaviour (SED) to light physical activity (LPA) significantly reduced Trail Making Test (TMT) completion times, suggesting improvements in cognitive processing speed. Conversely, shifting the same duration from SED to moderate-to-vigorous physical activity (MVPA) enhanced the accuracy rate on the TMT. Sedentary time was associated with longer TMT completion times but did not significantly affect the accuracy rate. Additionally, a dose-response relationship was observed, with increases in MVPA, caloric expenditure, and step count correlating with shorter TMT completion times. In contrast, increases in LPA and caloric expenditure were associated with higher TMT correct response rates.

Conclusion: The substitution of sedentary behaviour with physical activity may be a beneficial strategy to enhance executive function among young adults. These results underscore the importance of reducing sedentary time and promoting physical activity in the daily routine of young individuals to support cognitive development. Future research should explore the underlying mechanisms.