Actor Jesse Eisenberg's character in the movie "Zombieland"extolled the virtues of "cardio" as an apocalyptic survival tool. It probably didn't cross his mind it was making him a more scrumptious target for the walking dead.
All supposing a better-functioning brain is also a tastier one, that is. A growing body of evidence shows that regular exercise — be it resistance training or aerobic — helps ward off a host of cognitive impairments and enhances brainpower all life long.
"It's a medium-sized effect — but since we're talking about the brain, medium is good," says Michelle Voss, assistant professor of psychology at the University of Iowa and lead author on a 2011 review of the effect of exercise on cognition.
I'd say very good.
Voss and her team examined more than 100 studies on the topic and discovered some interesting things. Here's one: The brain benefits of resistance training (such as lifting weights) seem to differ from those you get from aerobic exercise. "Aerobic exercise improves ability to coordinate multiple things, long-term planning and your ability to stay on task for extended periods," she said. Resistance training, which is much less studied than the aerobic side of things, "improves your ability to focus amid distracters."
This makes sense to me: Aerobic exercise such as running involves staying on task for a long time, and if you're training to get better, you need to stick to a plan. Weightlifting requires ignoring the spandex and lousy gym music and focusing enough to prevent the barbell from crushing your trachea during bench press. Perhaps honing the discipline for aerobic exercise and/or learning to tune out gym distractions reaps benefits for the other, non-athletic parts of your life.
The details of what's going on inside the skull are fascinating. Voss explained that MRIs of people in their 60s showed increases in gray and white matter after just six months of exercise. This happens in the prefrontal and temporal lobes, sites that usually diminish with age. With exercise, Voss says, they grow.
Voss also explained that the hippocampus area of the brain, key for memory formation, shrinks 1% to 2% per year in those older than 60, but when people in this age group begin fitness regimens, it grows by 1% to 2% instead.
Beyond growing one's brain, exercise improves the ability of different parts of the brain to work together, Voss says. It talks to itself better, but not in a multiple-personality kind of way.
Exactly how hard were they pushing these over-60s? I could see how the excitement would be curtailed if you had to become a power-lifting marathoner to reap the benefits. But that's not the case. Simple brisk walking for 45 minutes three times a week gets results.
Going much beyond that won't give your brain much more, Voss added: "There definitely is a law of diminishing returns. The difference between zero and moderate exercise is significant, whereas the difference between moderate and high exercise is much less so."
What's definitely clear is this: Sitting = bad.
Exercise also can help if you've got a genetically programmedAlzheimer'stime bomb ticking away in your noggin. In 2000, Dutch researchers published a study of 347 men, some of whom were genetically prone to Alzheimer's due to a certain gene variant. Adjusting for a number of confounding factors such as smoking, drinking and education, the researchers found that the inactive couch potatoes with the brain-wasting gene variant were four times more likely to develop Alzheimer's than the workout warriors who carried the trait.
Voss agreed that people at greater risk for cognitive decline have the most to gain from being active. In other words, if your parents or grandparents are pouring milk into the dishwasher and putting salt in the sugar bowl, you need to get moving.
But even without genetic tendencies, exercise reduces your risk of developing silent brain infarcts. And if you surmise that "silent brain infarct" is something unpleasant, you're right. It's also called a "silent stroke." It's a lesion. On your brain. That's bad.
Columbia University researchers published a study of 1,238 elderly people in the journal Neurology last year, reporting that the 25% who were the most physically active were nearly half as likely to suffer these brain lesions compared with their inactive counterparts.
Cerebellums and cerebrums and medullas, oh my!
Scare tactics are lousy motivators for physical activity, so let's just forget all that doom and gloom stuff. (If you have the bad gene variant, forgetting should be easier.) Instead, focus on the benefits of enhancing brain function.
Last year, researchers from the University of South Carolina put 35 subjects on treadmills to figure out what exercise does for building mitochondria in the brain. If you remember middle school biology, you'll recall that mitochondria are the powerhouses of the cell.
Granted, these "subjects" were mice, and that's just as well, because the researchers then dissected the rodents' brain tissue and examined the difference between treadmill-aficionado mice and cage-potato mice. Lo and behold, eight weeks of treadmill running made mouse brains more fatigue-resistant, due to an increase in mitochondria. The little quadrupeds had pumped up their cognitive capabilities.
Voss explained that increased mitochondria increases the brain's ability to get blood and oxygen where it needs to go. "There is a shorter refractory period as well," meaning you recover quicker.
This comes in handy. When I go for a long run, cycle or other workout session, it's my brain that pushes me. I have to resist my legs saying, "Dude, we're done." My brain is what drives them by replying, "No, keep going." When your body is screaming at you to stop, it takes a tremendous effort of will to override that. I believe the mental aspect of exercise is primary.
Nike says, "Just do it," but understand that it's the brain that's doing; it's running the show and making those arms and legs move. And getting stronger, mile by mile.
So much for the dumb jock stereotype.
Fell is a certified strength and conditioning specialist in Calgary, Canada.