Purpose: The study aimed to provide evidence-based recommendations for the prescription of a single session of exercise to improve cognitive performance. In particular, the purpose was to determine the dose–response relation between exercise duration and cognitive performance for a moderate-intensity session of aerobic exercise.
Methods: Twenty-six healthy young men participated in a reading control treatment and three exercise treatments presented in a random order. The exercise treatments were designed on the basis of the American College of Sports Medicine guidelines and consisted of a 5-min warm-up, a 5-min cooldown, and cycling at moderate intensity (approximately 65% HR reserve) for 10, 20, or 45 min. The Stroop test was administrated after completion of each assigned treatment.
Results: Exercise at moderate intensity for 20 min resulted in significantly better cognitive performance, as assessed by shorter response time and higher accuracy. This result was found regardless of the type of cognitive function assessed. In addition, a curvilinear dose–response relation between exercise duration and cognitive performance was observed.
Conclusions: An exercise session consisting of a 5-min warm-up, 20 min of moderate-intensity exercise, and a 5-min cooldown improves cognition, whereas shorter or longer durations of moderate exercise have negligible benefits. This study provides the foundation for the prescription of a single session of moderate exercise to facilitate cognitive function in healthy younger adults.
Alex’s Notes: We know exercise is good for the brain. But how much is necessary? Understanding the dose-response relationship is important if we are to establish exercise prescriptions to facilitate cognitive performance. A previous meta-analysis of 74 studies found that exercise must last at least 11 minutes to have an effect. With regard to resistance training specifically, it was found that there is a positive linear association between lifting intensity and processing speed, but an inverted “U” shape curve for executive functioning whereby moderate intensity (70% of 10RM) was more beneficial than higher (100% of 10RM) or lower (40% of 10RM) intensities. The current study sought to assess the dose-response relationship for aerobic activity.
Twenty-six young normal-weight males (20-22 years) were recruited from two university campuses. They performed a submaximal exercise test on a cycle ergometer to estimate their VO2peak on one day, and then returned to the laboratory four more times with at least three days of rest between them. On these days the subject was randomly assigned to read a book related to exercise and cognition for 30 minutes (control), or cycle at a moderate intensity for 10, 20, or 45 minutes. After the test session, the subject would then complete the Stroop test.
As would be expected on this annoying test, the subjects had significantly longer response times and less accuracy during the incongruent conditions of the Stroop test when compared to the congruent. Cycling for 20 minutes was found to significantly reduce response time and significantly increase accuracy compared to the other trials (10 min, 45 min, or control), which were not significantly different from one another.
It appears that 20 minutes of moderate intensity aerobic activity is better suited for cognitive benefits on the Stroop test than longer or shorter durations, or simply doing nothing at all. However, executive function consists of several subcomponents such as shifting, updating, and inhibition. The Stroop test only provides a measure of inhibition. Thus, we cannot generalize these results to other aspects of executive functioning or other aspects of cognition.
Moreover, the study design was limited to testing durations of moderate intensity aerobic activity. How time would influence high-intensity work remains to be determined. Also, which would be better? So many questions left unanswered. Still though, if you ever need to do the Stroop test, it seems prudent to exercise (moderately!) for only 20 minutes.