Experimental Evaluation of the Joint Effects of Exercise and Sedentary Behavior on Cognitive Function.

Background: The objective of this study was to evaluate the potential joint effects of sedentary behavior and exercise on cognitive function.

Methods: Participants (Mage = 20 yrs) were randomly assigned to one of three experimental groups. The No Exercise Group (n = 19) was instructed to reduce steps to less than 5000/day and were not allowed to exercise for one-week; the Reduced MVPA (moderate-to-vigorous PA) Group (n = 18) was instructed to reduce steps to less than 5000/day but exercised for 50% of their previously reported vigorous PA for one-week; and the Control Group (n = 20) maintained normal activity for one-week. Cognitive functions (via Stroop and Trail Making tasks) were assessed at baseline, post-intervention, and after one week of resumed normal activity for the intervention groups.

Results: Statistically significant main effects for time were observed for Stroop Congruent (Ftime = 11.7, p < 0.001, η 2 p = 0.18), Stroop Incongruent (Ftime = 19.4, p < 0.001, η 2 p = 0.26), Stroop Control (Ftime = 54.4, p > 0.001, η 2 p = 0.50), Trail Making-A (Ftime = 19.1, p < 0.001, η 2 p = 0.26) and Trail Making-B (Ftime = 13.8, p < 0.001, η 2 p = 0.21) tasks. However, there were no statistically significant group x time interactions (all p's > 0.05) for any of the cognitive parameters.

Conclusion: These experimental findings do not suggest an interaction effect between sedentary behavior and physical activity on cognitive function.