When I run, I think about everything. My mind wanders here and there and by the time I’m done, it often feels like I’ve found solutions for every problem I’ve ever had. There’s likely some truth to that feeling, too: Brain-imaging studies have shown that after about 30 minutes of aerobic exercise, activity in the brain’s “frontal executive network system” increases; this is the region of the brain associated with things like problem-solving, decision-making, and planning. It’s empirical evidence for something every runner already knows — that the activity can help you think through the things that are troubling you. It’s why I love it.
It’s also why I hate it. Sometimes, I just want to shut my mind up and lock the world out, just for a little while. This year has been a long and weird one, and so I don’t think it’s a coincidence that I have somewhat recently embraced a rather specific new kind of workout: You could call it speedwork, or intervals, or the ridiculously named “fartlek” — in short, I am lately into running very, very fast. If long, slow runs provide the opportunity to think about everything, short, speedy runs give me, blessedly, a few brief moments to think about nothing. It’s like my body is working so hard that it requires the full attention of my mind, too.
It seems I am not the only runner who’s become less interested in distance. After “more than two decades of consistent and often double-digit increases,” Running USA reported earlier this year that the growth of road races across the country had finally stalled; the number of people running marathons, for instance, decreased 8 percent from 2014 to 2015. Running USA, a not-for-profit organization that tracks trends in the running industry, attributes the plateau in participation to the rise of nontraditional events — things like the Color Run, for instance — and that’s likely true; they would know. But it’s also interesting to note a simultaneous emerging trend: the rise of super-short races.
Take the 5th Avenue Mile, a New York Road Runners race that has existed since 1981, but in the last decade has seen its participation double. In 2006, there were 3,015 finishers; this year’s race had 6,152 finishers. This year also saw the introduction of the Brooklyn Mile, a brand-new race that took place in Williamsburg in August. Meanwhile, high-intensity interval training, or HIIT, has grown in popularity, thanks in part to eye-catching headlines promising results from a seven-minute workout, or even a one-minute workout. The evidence is suggesting that anaerobic interval training, as it’s sometimes called, is an effective substitute for longer bouts of moderate exercise, happy news for anyone who feels pressed for time (so, everyone). The fitness gained from either type of workout appears to be comparable. Quick but powerful (and often painful) workouts are having something of a moment.
As it turns out, my hunch about the cognitive effects of high-intensity interval training is likely correct. Sort of. Competing theories have emerged after more than three decades of scientific investigation into the subject, but generally speaking, it does indeed appear to be harder to think creative, abstract types of thoughts during an anaerobic workout as compared to an aerobic one. “When you have high exertion — meaning you are running flat-out in a race — you’re not going to be able to solve problems or think as well as when you are engaged in moderate exercise,” said Karen Postal, an instructor in psychology at Harvard Medical School and the president of the American Academy of Clinical Neuropsychology. As far as exercise’s “beneficial effect on thought,” she continued,“there is a sweet spot, which is a moderate level of intensity.”
Physiologically speaking, this is likely a byproduct of anaerobic functioning. During anaerobic exercise (like sprinting or weight-lifting), your body doesn’t take in oxygen like it does during an aerobic workout; instead, the activity causes an oxygen deficit. “You’re actually working on less available oxygen in your brain,” Postal said. You’re also pumping more blood to your muscles instead of your brain, she added. This does not bode well for highfalutin cognition while you work out.
If, however, the task at hand is something rote and noncreative — especially if it’s something you’ve done over and over again — your cognitive performance should improve during a bout of intense interval training. “So it’s something you do every day — maybe for your work you’ve got to assign people to different tasks in your office, for example,” Postal said. “It’s not something novel or ambiguous, but something rote that you do all the time. If you’re given an easy task, you’re able to do it faster if you’re moving faster.”
Additionally, some studies have suggested that if you are fit, HIIT can improve your executive functioning, perhaps especially concentration and focus. For those who are in shape, highly intense workouts seem to serve to wake their brains up; for those who are not, the exercise makes them too exhausted for more complicated cognitive tasks.
Overall, “what we know now is that exercise is going to improve your thinking ability while you’re exercising in a certain sweet spot, and that sweet spot is moderate intensity,” Postal explained. “If it’s too low, it’s not going to improve your thinking; if it’s too high, it’s going to make it harder to do certain types of thinking.” For many of us, then, it is indeed harder to engage in more abstract forms of thinking when you are simultaneously engaged in a difficult workout. (After the workout is done, by the way, it’s a different story; research has indeed suggested that things like memory, attention and processing speed improve after sedentary people adopt a high-intensity interval training program.)
So: Go for a long, slow run (or a bike ride, or swim, or whatever your preferred form of aerobic exercise may be) if you want to mull over your life. But try a short, intense workout if you want to quiet your mind for a little while. Just an idea for the last few weeks of this election season.