A Motivational Post for Exercise Procrastinators

I’m not an athlete. I don’t wake up in the morning itching to run, or skip to aerobics class at the Y. I exercise regularly, but it’s almost always driven by guilt and anxiety. If I don’t go, I’ll get fat. I’ll have less energy. I’ll die young. This kind of thinking isn’t a great motivator, they say. So today I’m trying a re-framing tactic: learning more about how, exactly, exercise can boost brain power.

(Caveat up front: Some studies have found that exercise does not improve cognition. I will be conveniently ignoring those in this post and in life.)

Exercise: Good now, good later!

The mental benefits of exercise begin while you’re doing it and continue in the hours afterward. Take two studies from the mid-90s that tested volunteers before, during, and after moderate-intensity stints on an exercise bike. In one study, students watched a screen while biking. The screen showed a square filling up with a color, and the volunteers’ task was to push a joystick button as soon as the square was full. Reaction times were significantly faster while biking than at rest.

In the other study, endurance athletes took a series of cognitive tasks before and immediately after reaching 75 percent of their maximum energy capacity on the bike. After exercising, the athletes showed much better scores on the famous Stroop test, in which they were shown color words (like red, blue, and green) but were asked to name the color of the letters in the word rather than read the word. It’s a tough test (try it!), and a standard measure of cognitive flexibility and executive function.

What if you don’t care about your mental abilities later today, you whine? Then exercise for your future brain. A 2009 study of more than 3,000 people showed that exercise habits in middle age can influence the risk of dementia some 30 years later. The researchers found that people who do regular exercise (such as playing sports) or light exercise (such as gardening or walking) in their 40s are significantly less likely to develop dementia three decades later compared with those who don’t exercise at all. (The study controlled for lots of other factors, too, including age, sex, education, diet, smoking, drinking alcohol, and body mass index.)

That’s no reason, mind you, for young people to take it easy. Another large Swedish study found that changes in cardiovascular fitness (again measured by stationary bike) between age 15 and age 18 predict cognitive performance scores at age 18.

Exercise: Curbs brain shrinkage!

If you’re not convinced by those behavioral studies, how about a neurobiological angle: Some research shows that exercise curbs the brain shrinkage that naturally happens with age. One group found that people who exercised (defined as sweating for at least 20 minutes at least twice a week) in middle age had more gray matter (brain tissue where neurons live) 21 years later compared with sedentary people. This shrinkage protection was especially prominent in the frontal lobes, whose activity is important for working memory, planning and attention.

If you’re already in your senior years, it’s not too late to jump on the exercise train. A few years ago, researchers studied 59 people aged 60 to 79, putting half in an aerobic exercise program and the other in a stretching program. After six months, those in the aerobic training showed increased gray matter and white matter (the connections between brain regions) compared with the stretching group. In a similar study of older adults, another team found that cardiovascular training improves spatial memory and slows down age-related shrinkage in the hippocampus, a region important for memory, by one to two years.

Exercise: Any type is good!

All of the aforementioned studies focus on aerobic exercise — the stuff that gets your heart beating and sweat rolling. That seems to be the most effective type, but if you’re just not up for that kind of exertion, I’ve got some other studies for you.

Why not try a low-intensity gymnastics workout? It boosts memory scores just as well as a more intensive workout, according to one study. How about lifting free weights twice a week? Improves scores on the Stroop test. Even “coordination training,” which focuses on eye-hand coordination and leg-arm coordination, improves performance on tests of visual attention.

And with that selective and highly unscientific review*, I’m officially out of excuses.

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*If you’d like more, um, real science, check out this report just published in Neuroscience and Biobehavioral Reviews.