1. 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).
2. 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.
3. It fights depression and anxiety. Depression slows the brain's ability to process information, makes it more difficult for us to concentrate and reach decisions, and causes real memory problems. For serious depression, your doctor may prescribe antidepressants. For milder cases, exercise may help lift your mood. It cranks up the body's production of serotonin and dopamine, brain chemicals crucial to happy mood. And it boosts levels of the feel-good chemicals called endorphins.
4. It reduces the effects of stress. If some hormones like BDNF make the brain younger, others help age it. These include the so-called stress hormone cortisol. Slow, scattered thinking and forgetfulness are caused by stress more often than we may realize. Exercise lowers cortisol levels, helping you to think straight again. It is also believed to help generate new nerve cells in the area of the brain called the dentate gyrus, an area of the hippocampus linked to the creation of new memories. Brain cells here are depleted during times of stress.
5. It improves your brain's executive function. Executive function basically means cognitive abilities like being able to focus on complex tasks, to organize, to think abstractly, and to plan for future events. It also encompasses working memory, such as the ability to keep a phone number in your head while you dial. When researchers set out to analyze the effects of exercise on executive function, they looked at 18 well-designed studies and found that adults aged 55 to 80 who did regular exercise performed four times better on cognitive tests than control groups who didn't work out. Effects were greatest among those who exercised 30 to 45 minutes each session for longer than six months, but substantial benefits were seen in as few as four weeks of exercise.
6. It increases sensitivity to insulin. When you eat, your body turns most of the food into glucose, or blood sugar, the main source of fuel for the body, including the brain. In order for that glucose to enter cells, it must be accompanied by the hormone insulin. Unfortunately, in some people, cells become resistant to insulin. The body then has to pump out more and more of it, and still blood sugar levels rise, often resulting in type 2 diabetes. And even if you don't develop type 2 diabetes, insulin resistance is bad for your brain. When brain cells are flooded by glucose, it can adversely affect memory and thinking.
Regular exercise, however, can reverse insulin resistance. In fact, your insulin sensitivity increases, stabilizing your blood sugar after you eat-for at least 16 hours after a single exercise session. The better your blood-sugar control, the more protected you are against age-related cognitive decline.