The Temporal Effects of Acute Exercise on Episodic Memory Function: Systematic Review with Meta-Analysis

Abstract

Background: Accumulating research demonstrates that the timing of exercise plays an important role in influencing episodic memory. However, we have a limited understanding as to the factors that moderate this temporal effect. Thus, the purpose of this systematic review with meta-analysis was to evaluate the effects of study characteristics (e.g., exercise modality, intensity and duration of acute exercise) and participant attributes (e.g., age, sex) across each of the temporal periods of acute exercise on episodic memory (i.e., acute exercise occurring before memory encoding, and during memory encoding, early consolidation, and late consolidation). Methods: The following databases were used for our computerized searches: Embase/PubMed, Web of Science, Google Scholar, Sports Discus and PsychInfo. Studies were included if they: (1) Employed an experimental design with a comparison to a control group/visit, (2) included human participants, (3) evaluated exercise as the independent variable, (4), employed an acute bout of exercise (defined as a single bout of exercise), (5) evaluated episodic memory as the outcome variable (defined as the retrospective recall of information either in a spatial or temporal manner), and (6) provided sufficient data (e.g., mean, SD, and sample size) for a pooled effect size estimate. Results: In total, 25 articles met our inclusionary criteria and were meta-analyzed. Acute exercise occurring before memory encoding (d = 0.11, 95% CI: −0.01, 0.23, p = 0.08), during early memory consolidation (d = 0.47, 95% CI: 0.28, 0.67; p < 0.001) and during late memory consolidation (d = 1.05, 95% CI: 0.32, 1.78; p = 0.005) enhanced episodic memory function. Conversely, acute exercise occurring during memory encoding had a negative effect on episodic memory (d = −0.12, 95% CI: −0.22, −0.02; p = 0.02). Various study designs and participant characteristics moderated the temporal effects of acute exercise on episodic memory function. For example, vigorous-intensity acute exercise, and acute exercise among young adults, had greater effects when the acute bout of exercise occurred before memory encoding or during the early memory consolidation period. Conclusions: The timing of acute exercise plays an important role in the exercise-memory interaction. Various exercise- and participant-related characteristics moderate this temporal relationship.

Acute exercise on memory function: open vs. closed skilled exercise

“…Previous studies have shown that acute exercise may, ptentially, improve retrospective memory. We, 28,29 along with others, 30,31 have summarized this effect elsewhere.…”

Does Engaging in Acute Exercise Prior to Memory Encoding and During Memory Consolidation have an Additive Effect on Long-Term Memory Function?

“…The purpose of this experiment was not to evaluate the effects of acute exercise vs. no exercise on long-term memory function. This has already been evaluated and demonstrated in numerous experiments [1,2,10,11,17,20,[25][26][27][28]. Before any definitive conclusion that acute exercise prior to memory encoding and during early consolidation does not have a superior effect when compared to acute exercise only prior to memory encoding, future work is needed.…”

“…First, it may be worth considering a higher intensity bout of exercise, particularly during the early consolidation period, as emerging work suggests that higher intensity acute exercise may enhance episodic memory to a greater extent than moderate-intensity acute exercise [13]. Second, recent meta-analytic research demonstrates a greater effect size for long-term memory when the acute bout of exercise occurs later (vs. earlier) in the consolidation period [17]. As such, future work that evaluates this additive paradigm should consider positioning the acute bout of exercise approximately 4-h after memory encoding [17], as opposed to immediately after memory encoding.…”

“…Second, recent meta-analytic research demonstrates a greater effect size for long-term memory when the acute bout of exercise occurs later (vs. earlier) in the consolidation period [17]. As such, future work that evaluates this additive paradigm should consider positioning the acute bout of exercise approximately 4-h after memory encoding [17], as opposed to immediately after memory encoding. Such a temporal shift may also be worth considering for the acute bout of exercise prior to encoding (i.e., alter the time period between the acute exercise bout and the memory stimuli).…”

“…When acute exercise occurs shortly before memory encoding, memory retention is enhanced [3,5]. There is also some emerging work demonstrating that when exercise occurs during the early consolidation period, long-term memory function may also be enhanced [17]. Acute exercise during both of these time periods may activate unique mechanisms to enhance long-term memory.…”