Exercise has been shown to benefit brain structure and function, particularly in aging populations. However, the mechanisms by which exercise exerts its effects, especially in humans, are not fully understood. This review argues that one reason for this knowledge gap is that exercise likely operates through multiple levels of mechanisms. Furthermore, the mechanisms of exercise may vary depending on factors such as age and health state. We discuss the state of evidence at each of three levels of analysis (molecular/cellular, brain structure/function, and mental states and higher-order behaviors) and highlight consistencies across these levels, inconsistencies within them, and knowledge gaps. Lastly, based on these, we speculate about which mechanisms of exercise may be universal across age groups and populations versus those that might be distinct to specific age ranges or populations.

中文翻译：

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运动对不同年龄组和健康状态的大脑和认知的影响

运动已被证明有益于大脑结构和功能，特别是在老年人群中。然而，运动发挥其作用的机制，特别是在人类中，尚不完全清楚。本综述认为，造成这种知识差距的一个原因是锻炼可能通过多个层次的机制进行。此外，运动机制可能会因年龄和健康状况等因素而异。我们讨论了三个分析级别（分子/细胞、大脑结构/功能、精神状态和高阶行为）中每个级别的证据状态，并强调了这些级别之间的一致性、它们内部的不一致以及知识差距。最后，基于这些，