The present study examined the effect of 4 physical-load conditions on interference control throughout a period of 45 min. A sample of 52 sport students was assigned to either a no, a low, an alternating low to moderate, or a moderate physical-load condition. A modified Eriksen-flanker task was administered in the preexercise period, 7 times during the exercise, and twice after completing the exercise. Significant interaction effects of time and condition, and significant time effects within condition on the reaction time of congruent stimuli and errors on incongruent stimuli, suggest a specific in-task effect of the alternating low to moderate and moderate physical-load conditions. Thus, it was concluded that moderate physiological arousal influences interference control by an increase of information-processing speed in tasks that require less cognitive control (congruent condition), which is at the expense of accuracy in cognitively more demanding tasks (incongruent condition).