It spurs brain growth
As we get older, the birth of new brain cells slows, and our brain tissue actually shrinks. Exercise may be able to reverse that trend. One brain-scanning study of healthy but sedentary people aged 60 to 79 showed significant increases in brain volume after six months of aerobic fitness training. No such changes occurred among controls who only did stretching and toning exercises. The researchers concluded that the improved cardiovascular fitness that comes with aerobic exercise is associated with fewer age-related changes in the brains of older people. Cardio boosts blood flow to the brain, which delivers much-needed oxygen (the brain soaks up 20 percent of all the oxygen in your body).
It boosts brain-building hormones
Much like plant food makes plants grow faster and lusher, the chemical known as brain-derived neurotrophic factor, or BDNF, stimulates the growth and proliferation of brain cells. This is especially true in the hippocampus, the brain region that is largely responsible for memory and which is particularly vulnerable to age-related decline. The more you exercise, the more BDNF you produce.