The effect of acute exercise on the formation of long-term memory

Though the body of literature converges on the notion that acute exercise has a small, positive effect on cognitive performance in general (Chang, Labban, Gapin, & Etnier, 2012; Lambourne & Tomporowski, 2010), effects on certain cognitive domains remain poorly understood. Among these cognitive domains, memory is one of the least studied within the acute exercise literature. Despite the lack of attention in the exercise literature, memory is an intriguing and important domain of study. Most effects of acute exercise on cognitive function abate relatively quickly following exercise cessation. However, if exercise can improve the ability to process and/or store newly acquired information, then it is conceivable that the product of these effects (i.e. - improved recall) could be observed well after exercise cessation. The purpose of this study was twofold. The primary purpose was to test whether a single bout of aerobic exercise affects performance on a long-term memory task. The secondary purpose was to determine whether that effect operates primarily through the encoding and/or consolidation processes of long-term memory formation. The secondary purpose was tested by manipulating the timing of exercise relative to exposure to the to-be-remembered material (word list). A within-subjects, repeated measures design was used. Participants completed 3 conditions in randomized order, including 2 treatment conditions and one control condition. Treatment conditions involved participants exercising either immediately prior to or immediately following word list exposure. Exercise prior to exposure could impact encoding or consolidation (E+C); whereas, exercise following exposure could only impact consolidation (C). The control condition involved no exercise (NE) at all. Exercise consisted of 20 minutes, at moderate intensity, on a cycle ergometer, as well as a 5-minute warm-up and a 5-minutecool-down (30 minutes total). Memory for the word list was assessed 60 minutes and 24 hours after participants had finished listening to it. Analyses revealed that the E+C condition produced significantly better recall of the word list following both the 60-minute (?p2 = 0.24) and 24-hour (?p2 = 0.22) delays. Pairwise comparisons revealed statistically significant differences in recall for the E+C condition versus the NE condition; however, no differences were observed involving the C condition. These results suggested that acute exercise can benefit long-term memory, and that this benefit is accomplished primarily through an effect on the encoding process.