The effects of acute exercise intensity on episodic and false memory among young adult college students

Background: Previous experimental work demonstrates that acute exercise may enhance episodic memory performance. However, limited research has examined the extent to which acute exercise influences false episodic memory production, and no studies, to date, have examined whether there is an intensity-specific effect of acute exercise on both true episodic and false episodic memories. Thus, the present experiment evaluated the effects of intensity-specific acute exercise on episodic memory and false episodic memory. Methods: A three-arm, parallel, between-group randomized controlled trial was employed in the University setting, with participants (N=60; M(age)= 20.8 years) randomized into a moderate intensity exercise group (15-minute bout of treadmill exercise at 50% heart rate reserve), a high intensity exercise group (15-minute bout of treadmill exercise at 80% heart rate reserve), or a control group (time-matched period of sitting). True episodic and false episodic memory were both assessed using 6 word-lists from the Deese-Roediger-McDermott (DRM) paradigm, including both a short-term recall and a delayed memory recognition assessment. Results: For the number of words recalled across each of the 6 lists, there was a significant main effect for list (P<0.001, η(2)(p)=0.15), marginally significant main effect for group (P=0.07, η(2)(p)=0.09), but no list by group interaction effect (P=0.44, η(2)(p)=0.03). Those in the high-intensity exercise group recalled significantly (P<0.05) more words than the control group. For the false episodic word recall, across various lists, high-intensity acute exercise was associated with a greater rate of false episodic memories. For the memory recognition task, there was no main effect for word type (P=0.46, η(2)(p)=0.01), group (P=0.4443, η(2)(p)=.03), word type by group interaction (P=0.44,η(2)(p)=0.03), recall by group interaction (P=0.4441, η(2)(p)=0.04), or word type by recall by group interaction (P=0.32, η(2)(p)=0.04). However, there was a main effect for recall (P<0.001, η(2)(p)=.54)and a word type by recall interaction (P<0.001, η(2)(p)=0.77). Conclusion: These findings suggest that acute high-intensity exercise may enhance true episodic memories, and, possibly, also increase the rate of false episodic memories. We discuss these findings in the context of how different acute exercise intensities may have unique and differential effects on underlying mechanistic processes related to true and false episodic memory.