The effects of a single bout of high intensity aerobic exercise on the long-term memory of younger adults

Abstract

University evaluations often reflect an individual’s ability to memorize and recall lecture material during exams. Consequently, the ability to effectively encode, store, and later retrieve information is an integral part of learning and academic success. Notably, students who are more physically active tend to have better academic performance. The neurobiology of stress is a strong candidate for the mechanism underlying this exercise-cognition interaction. Given that exercise is a physical stressor, it is hypothesized that exercise-induced adrenocortical activations increase cortisol levels. Critically, cortisol increases memory consolidation for newly learned information. One hundred twenty-eight young adults (36 males; age: M±SD =19.47±1.55 years) viewed a video lecture before exercise (n = 41), after exercise (n = 42), or after rest (n = 45). The exercise was high intensity interval training on a cycle ergometer and memory for the lecture material was assessed using a multiple-choice quiz conducted 14 minutes and 48 hours after the lecture. There was a significant positive correlation between aerobic fitness and grade point average [r(95) = 0.22, p < .05], immediate recall [r(100) = 0.39, p < .001], and delayed recall [r(98) = 0.28, p < .01]. A mixed model ANOVA found a significant main effect of group on comprehension of the lecture material, F(2, 96) = 3.34, p < .05, revealing greater memory benefits at both 14 minutes and 48 hour delays for those who exercised compared to those who did not exercise; however, pairwise comparisons found this effect specific to the exercise post group. There was also a main effect of group on cortisol levels, F(2, 107) = 3.97, p < .05; however, only the exercise prior group exhibited significantly greater levels than the control group. Thus cortisol levels collected during the experimental session did not clearly differentiate the exercise conditions or reflect the observed memory benefits for the exercise post group. This may have resulted from the gradual increase in cortisol following exercise that had time to increase when exercise was completed at the beginning of the exercise session (exercise prior) rather than at the end (exercise post). Overall, this study suggests that both physical fitness and an acute bout of aerobic exercise are associated with academic and memory performance. More research is needed to understand the mechanism.