Exercise for your brain? Aerobic exercise found to maintain brain volume in the left hippocampus in 14 different controlled trials suggesting aerobic exercise may prevent brain aging. The exercise protocols in the 14 trials ranged from walking to jogging to cycling. The duration range was from 6 weeks to 24 months. Aerobic exercise has been shown to increase brain-derived neurotrophic factor, IGF-1, and serotonin in the brain. All of these growth factors play a role in maintaining neurons and neurogenesis (the growth of new neurons) and have been shown to cause exercise-induced neurogenesis in animal studies. Just so many reasons to be physically active.