Doing aerobic exercises four hours after memorizing something, but not exercising right after, has been linked to better recall, according to a series of studies from the Netherlands.
The research has discovered that newly-learned information can turn into long-term knowledge using a process of integrating memories and stabilization. To accomplish this process, certain brain chemicals – such as those released during physical activities, including dopamine, noradrenaline (norepinephrine) and a growth factor called BDNF – are necessary.
Guillen Fernandez, senior author on the study and director of the Donders Institute for Brain, Cognition, and Behavior in Nijmegen, the Netherlands, told Reuters that,
The brain processes new memories for a while after learning. Physical exercise is able to improve these post-learning processes.
For the study, the researchers recruited 72 participants and directed them to learn how to match a series of 90 locations with pictures in 40 minutes. The participants were divided into three groups: one exercised right after the task, the second exercised four hours later and the third group did not exercise at all. The groups doing exercise went on a stationary bike for 35 minutes, with sudden spurts of intensity in the activity.
After two days, the participants were asked back to the lab to test how much of what they had initially memorized had stuck. During the recall test, each participant was in an MRI scanner so that the researchers could track the activity in different parts of their brains.
The participants in the group that had exercised four hours after the memorization task remembered much more information, while those who exercised right away and the group that did not exercise showed little variation in recalling what they had learned.
The researchers also found that activity in the hippocampus, the part of the brain associated with creating memories, was quite similar among the people in the four hours after exercise group during the recall test. Hippocampus activity was much less consistent in participants in the other two groups.
These results suggest that the consistency of hippocampus activity in the delayed exercise group could mean there is a greater “efficiency or coherence” in how the brain pulls up memories and “might relate to differences in memory strength.”
Fernandez notes that stronger memories will always be remembered, but the weaker memories that are normally forgotten in a day or two may last longer if more dopamine and norepinephrine are released.
People who want to improve their learning and recall functions are advised to perform rigorous exercises to make sure that enough brain chemicals are released. Fernandez also cautioned not to take it too far, as “very intensive exercise might also have negative effects.”
The researchers say that more studies are needed to see if exercise will help memory recall for more than two days, the time frame of their study. They also point out that the type of memory being employed might be significant in doing delayed exercise, and “procedural” tasks like learning to tie shoelaces might be better helped by doing immediate exercise.
Marc Roig, an assistant professor at McGill University in Montreal, Canada, says that having a regular exercise routine may help memory retention as well. Several weeks of physical activity like jogging or cycling can make the hippocampus larger, improving recall.
Roig adds that the kind of exercise might not matter. “Most studies have looked into aerobic exercise but recent data shows that resistance training and high intensity interval training may also be beneficial.” He says to maximize training for improving memory, it’s good to focus not just on the method but also on the time of training, to achieve the best results. Roig was not involved in the study, but studies cardiovascular exercise in relation to memory retention.
The study was published in Current Biology.