The Intensity of Your Workout Could Determine How It Affects Your Memory, Study Finds

While scientists have long understood that exercise benefits brain health, it hasn’t necessarily been clear how this relationship works until relatively recently. Thanks to new research, this year alone, we’ve learned that when your muscles contract during exercise, they release molecules called myokines that stimulate neuron function, and that even small amounts of physical activity daily can protect your brain from cognitive decline “by enhancing blood flow to the brain and stimulating biochemical pathways that maintain the functional and structural integrity of neurons,” Arjun V. Masurkar, MD, PhD, clinical core director of NYU Langone’s Alzheimer’s Disease Research Center, previously told Well+Good.

Mind blowing, right?

Adding to the brain trust: Research published last February found that aerobic exercise boosts episodic memory, and now scientists at Dartmouth College have taken that a step further by determining that while aerobic (moderate intensity) exercise improves episodic memory, anaerobic (or high-intensity) exercise strengthens spatial memory—both of which play significant roles in your ability to recall different types of information.

The difference between episodic and spatial memory

Typically, people tend to think of memory falling into one of two categories—long-term (something that happened during childhood, for example) or short-term (the combo to your gym locker you set an hour ago). But your memory looks more like a tree with many different branches, and out on those limbs are episodic and spatial memory.

“Episodic memory is remembering events that have happened, places you’ve been, people you’ve met, what you ate last night for dinner, what you read in a book, etc.,” explains Sarah Kremen, MD, director of the Neurobehavior Program at Cedars-Sinai Medical Center in Los Angeles. You can think of it as the autobiographical details of your life.

Spatial memory is more about being able to recall how to get to a place or where to locate a specific item. And just like with real tree branches, there’s overlap between the two, says Dr. Kremen. Being able to remember where you parked your car and then finding it again is an example of what she calls spatial-episodic memory. The ability to remember things episodically and spatially applies to both long- and short-term recollections.

Why you want to keep both your episodic and spatial memory strong

Episodic and spatial memory originate in different parts of the hippocampus, according to Dr. Kremen. “It’s significant because usually, at least in most people, the part of the brain that helps you learn new verbal facts or verbal information [episodic memory] is the left hippocampus,” she says. “The part of the brain that helps you learn new spatial information is the right hippocampus.” So it behooves you to be thinking about boosting both “because different types of memory subserve different skills and requirements that you need in order to function in the world around you,” Dr. Kremen explains.

If you are having trouble remembering events, she says, then it’s hard to know what’s happened in the past and how to navigate the future (e.g. if you can’t remember that you had a doctor’s appointment or what a doctor told you in the past, then it’s hard for you to provide correct information to the next doctor; or if you can’t remember that you paid a bill, then you may pay it twice).

There are lots of ways to boost your memory—but exercise should be on your short list, according to Dr. Kremen. “We know that exercise is just as important as taking your medications as directed by your doctor, taking care of your mental health, or eating a healthy diet,” she says. Ideally, you should be doing a mix of anaerobic and aerobic exercise every week.

The best workouts to boost both types of memory

The Dartmouth study used data from the fitness trackers of its subjects, who were asked to perform memory tests. It looked at heart rate metrics to determine the exercise intensity of each participant’s workouts for a year.

There isn’t one specific type of workout that’s best to boost episodic or spatial memory, but rather, you can do anything that falls into the moderate- or high-intensity range for you. No fitness tracker? No problem. You can use the RPE (rate of perceived exertion) scale to determine your moderate and high intensity levels:

• 0  to 1: Very light—feels like nothing at all
• 2 to 3: Light—feels like you can do activity for hours and maintain a full conversation
• 4 to 5: Moderate to light—feels like you can maintain for hours, can say full sentences before needing to break for a breath
• 6 to 7: Moderate to hard—feels like you can maintain the effort for an hour or two; you’re breathing heavily, but can still say a full sentence
• 8 to 9: Hard to very hard—work is uncomfortable
• 10: Very, very hard—maximum work, can only maintain this effort for a few seconds at a time

To count as anaerobic exercise, you’ll need to be working at 80 percent of more of your max heart rate (or an 8 or higher on the RPE scale), and for aerobic exercise, you’ll want to stick to 50 to 70 percent of your max heart rate (or a 5 to 7 on the RPE scale).

Since both types of exercise are beneficial for brain (and overall) health, try to work in some of each every week. In general, you should aim for a mix of 65 percent aerobic exercise and 35 percent anaerobic, Fhitting Room trainer Ben Lauder-Dykes previously told Well+Good. How you choose to spend those minutes is up to you.