•Performing aerobic exercise 4 hr after learning improved associative memory
•Exercise at this time also increased hippocampal pattern similarity during retrieval
•Exercise performed immediately after learning had no effect on memory retention
•Exercise could have potential as a memory intervention in educational settingsSummary
Persistent long-term memory depends on successful stabilization and integration of new memories after initial encoding. This consolidation process is thought to require neuromodulatory factors such as dopamine, noradrenaline, and brain-derived neurotrophic factor. Without the release of such factors around the time of encoding, memories will decay rapidly. Recent studies have shown that physical exercise acutely stimulates the release of several consolidation-promoting factors in humans, raising the question of whether physical exercise can be used to improve memory retention. Here, we used a single session of physical exercise after learning to exogenously boost memory consolidation and thus long-term memory. Three groups of randomly assigned participants first encoded a set of picture-location associations. Afterward, one group performed exercise immediately, one 4 hr later, and the third did not perform any exercise. Participants otherwise underwent exactly the same procedures to control for potential experimental confounds. Forty-eight hours later, participants returned for a cued-recall test in a magnetic resonance scanner. With this design, we could investigate the impact of acute exercise on memory consolidation and retrieval-related neural processing. We found that performing exercise 4 hr, but not immediately, after encoding improved the retention of picture-location associations compared to the no-exercise control group. Moreover, performing exercise after a delay was associated with increased hippocampal pattern similarity for correct responses during delayed retrieval. Our results suggest that appropriately timed physical exercise can improve long-term memory and highlight the potential of exercise as an intervention in educational and clinical settings.