Experimental effects of acute exercise on episodic memory acquisition: Decomposition of multi-trial gains and losses

Objective: Research demonstrates that acute exercise may enhance retention of multi-trial episodic memories. Previous work has examined the effects of exercise on the mean level of memory recall. However, no study has examined whether exercise can influence the acquisition of new items, which was the purpose of this experiment. Methods: Using a randomized controlled trial design, participants (young adults; M-age = 22 yrs) completed either a high-intensity bout of treadmill exercise for 15-min (n = 22) or sat (n = 22) prior to completing a multi trial episodic memory task. This task involved recalling 15 words for six successive trials, as well as after a 20-min delay (Trial 7). The performance on the multiple trials was categorized into gains (items not recalled on Trial n that were recalled on Trial n + 1) and losses (items recalled on Trial n that were not recalled on Trial n + 1). Results: The exercise group recalled more words on Trial 6 (11.4 vs. 9.7; P = 0.009) and after the 20-min delay (10.9 vs. 9.4; P = 0.01). The exercise group (vs. control) had a smaller proportion of losses from Trial 3-4 (10.4% vs. 20.3%; P = 0.04) and had a greater proportion of gains from Trial 5-6 (38.5% vs. 14.8%; P = 0.01). Conclusions: The exercise-induced multi-trial memory effect may be influenced by greater item gains.