That 28-minute HIIT workout is quick, hard, and seemingly effective for building muscle and burning fat—but have you ever thought about what it might be doing to your brain?
It’s been proven that physical activity changes the brain’s structure, and usually improves brain health. We’re well aware that participating in physical activity encourages the brain to instantly produce endorphins and other mood-boosting hormones, and regular exercise is even recommended as a way to stave off potential issues like dementia and Alzheimer’s disease later in life. Studies usually show that, like meditation, exercise increases brain volume.
But for the first time ever, researchers have been able to study the effects that certain types of exercise—running, HIIT-style workouts, and weight training—have on the brain. And the results are pretty stunning.
First published in the Journal of Physiology, the study compared the effects of exercise on different groups of rats. OK, yes, we know what you’re thinking—how did they convince a lab rat to do Kayla Itsine’s leg day workout? It’s actually quite cute: Once a day, the HIIT rats did an interval “workout”—sprints for three minutes, walk for two minutes, repeat—on a mini rat treadmill for 15 minutes a day. The weight training rats had a weight tied to their tails, and did workouts by climbing a wall (sounds tough!). The running rats hopped on their mini rat treadmills and ran at an aerobic, easy speed for a few miles a day.
Just take a second to picture all of that in your head. You’re welcome.
OK, so after committing to this workout routine for 6 to 8 weeks, what happened to their brains? Scientists found that the runners had very high levels of neurogenesis—the creation of new brain cells in a mature brain. These rats had lots of new cells in the hippocampal region, the area neuroscientists believe controls emotions, memory, and the autonomic nervous system. Bonus: The farther they ran, the more neural activity they had.
Unfortunately, the HIIT and weight training rats didn’t see as exciting results. Compared to a group of sedentary rats, the study participants saw a “very modest” effect of HIIT on neurogenesis. Weight training had zero effect on the brain, the same impact as a sedentary lifestyle. Researchers did note that weight training rats experienced “gains” and got physically stronger, so at least they got something out of the whole experiment.
Here’s the thing—rats aren’t people. But researchers believe the results of the study suggest that aerobic exercise, like running or biking, could be the “most beneficial for brain health in humans.” Maybe it’s time to finally sign up for that half-marathon you’ve been thinking about?