It’s no secret that regular exercise has many benefits. It protects against developing chronic conditions, such as diabetes and heart disease, and in some cases can improve mental health. But what effect does it have on specific functions, like memory? Can a workout regimen help you remember the scores from last night’s Yankees game, where you went on your first date with your significant other or where you left your keys?
It’s possible. Studies over the years have suggested that a single workout can improve recall, and that engaging in regular exercise over the course of years or decades not only improves memory, but also helps fortify against future memory problems. Now, a recent study from Dartmouth focuses on how the intensity of exercise, over a period of time, may play an important role in bolstering different types of recall.
“We know that exercise works, but we don’t know which variables of exercise make the exercise more effective,” said Marc Roig, a physical and occupational therapy professor at McGill University who studies the effect of exercise on cognition and was not involved with the study. “We believe intensity is one of those factors.”
Different exercise intensities appear to affect different types of memory.
One of the major challenges with studying the link between regular exercise and memory is that the changes are hard to measure. This is complicated by the fact that many other factors affect memory, like working a sedentary office job or chronic sleep deprivation. Furthermore, there are different types of memory — which explains how a person might constantly lose their keys (poor spatial memory) but have a knack for remembering birth dates (strong semantic memory).
Activity trackers can offer one solution to these issues. In the recent paper, published in the journal Nature Scientific Reports, researchers were able to look at a year’s worth of Fitbit data from 113 participants, who also completed a series of memory tests, like recalling details from a short story, spatial details, foreign language terms and lists of random words.
The advantage of this method is that it linked a full year of information about participants’ activity patterns — how much exercise they got, how intense, how often — to their performance on memory tests.
Other studies have tracked patterns of activity through self-reported data, which is often less reliable than activity tracker data, as people tend to underestimate how much time they are sedentary and misremember their total activity levels.
“You can get a much more nuanced picture from activity tracker data,” said Jeremy Manning, a professor at Dartmouth College and one of the authors of the study.
Dr. Manning and his colleagues found that active people had better memories overall compared to those who were sedentary, but also found that the types of tests they did well on varied depending on how intensely they exercised.
For instance, participants who engaged in light to moderate activity, such as going for regular walks, had better “episodic” memory. Think of episodic memory as “mental time travel,” Dr. Manning said, or the ability to remember details about everyday events, like meeting a friend in a coffee shop or watching for the school bus on your first day of kindergarten.
This tracks with a number of previous studies that have shown the more people are active, the better, on average, their episodic memory is.
Participants who regularly exercised more intensely — such as going for a run or doing a HIIT workout — were more likely to perform better on spatial memory tasks. Spatial memory is the ability to remember physical relationships between objects or locations in space, like where you put your keys. This mirrors a number of other studies that show high-intensity exercise improves memory, but goes further, suggesting it might be more helpful for this type of memory over another.
More study needs to be done to solidify these associations and determine what is causing them, the researchers said.
“The more that we can connect everyday patterns of activity to cognitive performance, the closer we are getting to thinking about lifestyle,” which includes how active you are during the entire day and sleep patterns, said Michelle Voss, a cognitive neuroscientist at the University of Iowa, who was not involved in the study.
According to Phillip Tomporowski, a professor of kinesiology at the University of Georgia who was not involved in the study, this paper is a “really good first guess” at how certain patterns of exercise affect certain types of memory.
Dr. Manning and his colleagues hope to follow up with controlled experiments to identify why certain exercises might affect specific types of memory.
Maybe someday there will be a workout to finally help you remember where you put your keys.
Rachel Fairbank is a freelance science writer based in Texas.