Cortical activity and network organization underlying physical and cognitive exertion in active young adult athletes: Implications for concussion.

OBJECTIVES To examine the neurophysiological correlates and brain network organization underlying physical and cognitive exertion in active young adults. DESIGN Repeated measures. METHODS Thirteen healthy adults completed three exertion tasks in a counterbalanced order: a graded working memory task (anti-saccade and serial addition task (ASAT)), a graded exercise task (cycling on a stationary bicycle) (EX) and a combined graded working memory and exercise task (ASAT+EX). All three tasks were performed under five levels of increasing difficulty. Continuous EEG was recorded in each session. Heart rate, perceived exertion and accuracy on the working memory task were recorded throughout. Power spectrum analysis and graph theoretical analysis was applied to the EEG data. RESULTS Heart rate and perceived exertion increased with exercise load and in both the EX only and ASAT+EX tasks. Overall accuracy was equally high for the ASAT and ASAT+EX tasks. Analysis of EEG data showed there was an increase in theta power associated with the ASAT+EX task and increase in functional connectivity in the frontal regions of the brain compared with ASAT only task. Accuracy decreased in the last two blocks when the task was most difficult. This decrease in accuracy was associated with a decrease in theta power and a decrease in functional connectivity. CONCLUSIONS Combined physical and mental exertion results in significant changes in perceived exertion, EEG theta power and network organization in healthy adults and will be valuable in revealing residual neurocognitive deficits after sports related concussion.