A recent study at the University of Jyvaskyla in Finland compared the effects of weight training, HIIT, and distance running on the brain, and discovered a clear winner:
This University of Jyvaskyla study, published in the Journal of Physiology and popularized by this New York Times article, concluded that sustained aerobic activity catalyzed robust levels of adult neurogenesis. This is the creation of new brain cells in the already mature adult brain, and primarily occurs in the hippocampus.
Lead by research fellow Dr. Miriam Nokia, the study examined four groups of rats: one sedentary control group, one group simulating weight training, one simulating HIIT, and one simulating distance running. The “weight training” group of rats and the sedentary group both showed no discernible augmentation of neurogenesis (read: weight training was no better for the brain than no exercise at all!). The “HIIT” group displayed minimal augmentation of neurogenesis, and the “distance running” rats displayed significant augmentation of neurogenesis, which increased with mileage. Not only was it proven that distance running best promoted adult neurogenesis, but it was also clearly shown that running longer and more often is even better.
According to Dr. Nokia, this is likely the same in humans. Running promotes what is called B.D.N.F. (Brain Derived Neurotrophic Factor) which is known to regulate neurogenesis in humans. HIIT promotes lower levels of B.D.N.F, yet also increases stress which inhibits neurogenesis. Weight training has no effect on B.D.N.F. levels.
Stress and cortisol also play a role. Distance running is proven to release stress and even has an antidepressant effect unlike the more stressful HIIT and weight training. The meditative qualities of distance running further promote a healthy brain.
While distance running and general aerobic endurance exercise is best for the brain, HIIT and weight training still are extremely beneficial to physical and mental health. Both are incredible for muscular health, bone health, and the increase in blood flow to the brain. Not to mention, HIIT and weight training have incredible proven results on athletic performance, metabolic health, and weight loss. Yet, if you never engage in aerobic endurance exercise, perhaps now is the time to add this to your routine!