People who are physically active often report feeling a “runner’s high”, or a feeling of extreme happiness and reduced pain following exercise. This effect is due to chemical signals called endocannabinoids, which are released by cells during exercise and travel through the bloodstream to the brain where they produce the euphoric effects. Research has shown that these compounds may also promote memory formation, but there is still much to be learned about the relationship between exercise and memory.
Researchers at the University of Geneva were interested in learning more about the relationship between exercise and the brain. Specifically, they looked at how exercise intensity and endocannabinoid levels affected memory, and what parts of the brain were affected in the process. To test these hypotheses, they recruited 15 young, healthy men who were not athletes. They asked each of the young men to take a memory test before and after a rest period, 30 minutes of moderate cycling, or 15 minutes of intense cycling.
On the test, which was designed to look at motor sequence learning, participants learned to press specific sequences on a keyboard. Motor sequence learning is a kind of motor memory in which someone learns a series of motions, such as a dance, and can anticipate each upcoming motion, performing them quickly and smoothly. Besides comparing the test results, researchers also looked at fMRI scans of the men’s’ brains while they were completing the tests, which showed which parts of the brain were active, as well as blood tests, to look at the endocannabinoid levels in the blood. They found that individuals who did 15 minutes of intense exercise had the highest scores, and the individuals who were at rest prior to the test scored the lowest. From the blood test and fMRI, they also discovered that both levels of endocannabinoids in the blood and activity in the hippocampus (a brain structure important for memory formation) correlated with test scores. From these results, the scientists concluded that intense exercise had the greatest benefit on motor memory.
The hippocampus, pictured above in green, is crucial for memory formation.
Image Source: Dorling Kindersley
The scientists’ conclusions have important real-life applications. Learning more about how exercise and memory are linked can help to guide how physical education programs are designed in schools, or how fitness plans can be designed to better help individuals with Mild Cognitive Impairment or Alzheimer’s disease. Though there are still many unanswered questions, this research contributes to an increased understanding of how exercise benefits memory.
Featured Image Source: David Mark
