Exercise and Implicit Memory: A Brief Systematic Review

Abstract

Background Emerging work demonstrates that acute exercise may enhance explicit memory function. No published systematic reviews have evaluated the totality of research examining the effects of exercise on implicit memory function, which was the purpose of this systematic review. Methods Databases (PubMed, PsychInfo, and Sports Discus) were searched to evaluate animal and human experimental studies evaluating the effects of exercise on implicit memory function. Results Among the 10 evaluated studies that met inclusionary criteria for this systematic review, 7 were conducted in animal models (rats or mice), with 3 utilizing human samples. Among the seven animal model studies, all employed a fear conditioning paradigm to evaluate implicit memory performance. All six animal studies employing a chronic exercise paradigm demonstrated evidence for associations between chronic exercise and enhanced fear conditioning. The one animal study evaluating a high-intensity acute bout of exercise showed that high-intensity acute exercise worsened implicit memory retrieval. Among the three human studies, one demonstrated a beneficial effect of acute exercise on implicit memory function. Discussion There is consistent evidence in animal models that chronic exercise enhances implicit memory, as assessed by fear conditioning. However, there have been too few human studies investigating this topic to render any meaningful conclusions regarding the relationship between exercise and cognitive-based implicit memory among humans.