OBJECTIVES The first aim of this study was to elucidate the effects of a single high-intensity strength exercise until failure on behavioral (i.e., attention) and physiological (i.e., salivary cortisol) responses. The second goal was to evaluate the effect of the performance of the cognitive tasks on cortisol levels. METHODS Fourteen physically active subjects completed a physical stress exercise consisting of six sets of squat repetitions to failure. Salivary cortisol and cognitive functions were evaluated in counterbalanced order prior to and following exercise-induced stress. RESULTS The results showed lower cortisol levels before the exercise and higher cortisol values before the cognitive task (p < 0.05). CONCLUSION Exerciseinduced stress had a detrimental effect on attention. Furthermore, the effects of stress on cognitive performance seemed to depend on the time elapsed between the cessation of the exercise and the evaluation of these but not the type of highintensity exercise performed.