Experimental and agent-based simulation analysis of collective escape in mice: Validation and density-dependent effects of obstacles.

On average a single bout of exercise transiently and modestly improves declarative memory [–]. A variety of factors have been hypothesized to moderate the magnitude of the improvements, including the timing of the exercise bout [,], the intensity of the exercise [] and characteristics of the study participants such as their psychological health status and age []. For example, among children and adolescents with attention-deficit/hyperactivity disorder (ADHD), current evidence suggests that acute exercise does not alter short-term memory []. This conclusion is based on three experiments with ADHD children aged 8–14 whose memory was tested for non-language stimuli following a brief encoding period and tested from immediately to 10-minutes after moderate intensity exercise [–]. Multiple factors potentially account for the null effects of acute exercise on memory in these samples, including age, small sample bias, ADHD status, the moderate exercise intensity, and the timing of the exercise. The timing of acute exercise, such as whether it occurs before or during memory encoding (when information is initially learned) or later when memories are becoming stabilized (memory consolidation phase), appears to moderate cognitive responses. An analysis of 25 acute exercise studies, for example, found that exercise performed prior to encoding improved memory by a small average magnitude (Cohen’s d effect size of 0.11, based on 66 effects) while exercise performed during early and late phases of memory consolidation (defined as less than or ≥ 4 hours after memory encoding, respectively) had moderate (d = 0.47, based on 66 effects) and large effects (d = 1.05, based on 3 effects) []. This analysis showed a clear advantage of timing exercise after encoding. A separate meta-analysis found that exercise after encoding compared to exercise prior to encoding induced larger mean effects for recognition memory (Cohen’s d = 0.60 vs. −0.06) but not for free-recall memory (d = 0.19 vs. d = 0.40), concluding that exercise timing has differential effects on different aspects of episodic memory []. The intensity of a single bout of exercise may be a moderator of the cognitive responses. Systematic reviews have drawn different conclusions based in part on including different investigations and analyzing the data in different ways. For example, an early review found that post-exercise memory was best following low-intensity exercise [], subsequent reviews found better memory performance after vigorous exercise [,], and the most recent review concluded no moderator effect of exercise intensity []. It is plausible that the relationship between memory and the intensity of acute exercise is not straight forward. For instance, there is emerging evidence that exercise intensity interacts with other relevant variables, such as the post-exercise recovery time, to moderate cognitive responses [].