Purpose: This study examined the aftereffects of cognitively demanding acute aerobic exercise on working memory in middle-age individuals.
Methods: In a within-participants design, middle-age males (n = 28) performed a two-back task to assess working memory before, immediately after, and 30 min after the following three interventions: 1) a rest-cognition intervention, in which they performed a cognitive task on a cycle ergometer without exercising; 2) an exercise-cognition intervention, in which they simultaneously exercised on a cycle ergometer and performed a cognitive task; and 3) an exercise-only intervention, in which they only exercised on a cycle ergometer.
Results: The exercise-only intervention resulted in increased hit rate and decreased reaction times and intraindividual variability on correct rejection trials, suggesting that simple aerobic exercise had a beneficial impact on working memory. By contrast, the exercise-cognition intervention resulted in increased intraindividual variability on correct rejection trials, which is suggestive of cognitive fatigue resulting from the additional cognitive demands. Such a decline was not observed even in the rest-cognition condition.
Conclusions: Cognitive fatigue caused by additional cognitive demands during aerobic exercise may cancel beneficial postexercise effects on working memory. Cognitively demanding acute aerobic exercise appears to be less effective than simple aerobic exercise in improving executive function.