The purposes of this study were to examine the effect of acute incremental exercise on the performance of a central executive task; the responses of the sympathoadrenal system (SAS) and hypothalamic-pituitary-adrenal axis (HPAA) during exercise, while simultaneously carrying out the central executive task: and the ability of Delta plasma concentrations of epinephrine, norepinephrine, adrenocorticotropin hormone (ACTH) and cortisol to predict Delta performance on the central executive task. Subjects undertook a flanker task at rest and during exercise at 50% and 80% maximum aerobic power (MAP). SAS and HPAA activity were measured pre- and post-treatment by plasma concentrations of catecholamines, and cortisol and ACTH, respectively. Reaction time (RT) and number of errors for congruent and incongruent trials on the flanker task showed significant main effects with performance at 80% MAP higher than in the other conditions. RT post-correct responses were significantly faster than RT post-error at rest and 50% MAP but not at 80%. Pre- and post-treatment catecholamines showed a main effect of exercise with a linear increase. Post-treatment ACTH concentrations at 80% MAP were significantly greater than in the other conditions. Delta epinephrine and ACTH combined were significant predictors of Delta RT and Delta norepinephrine was a significant predictor of Delta number of errors. It was concluded that exercise must be at a high intensity to affect performance on the flanker task. Both the SAS and HPAA appear to play a role in the exercise-cognition interaction. (c) 2009 Elsevier B.V. All rights reserved.