How does exercise affect my cognitive function?

There are several ways exercise can improve the cognitive function. First  exercise will increase blood flow to the brain, providing the brain with essential nutrients such as glucose and oxygen.
Abnormal glucose tolerance can lead to brain impairments, and exercise helps regulate blood sugar levels.
In children, exercise has been shown to improve cognitive function, and improve motor skill development. Children who are active do better on standardized tests and have better grades. In adults, especially as we age, regular physical activity increases memory and slows the aging process of the brain. Studies show that very active people who engage regularly physical activities have much lower rates of memory loss, dementia, Alzheimer’s and do better on cognitive function tests over time.  

Physical exercise that involves the rhythmic movement of large muscle groups -- swimming, cycling, running, walking, rowing, and so on -- seems to be most effective in relieving stress or preventing depression, both of which impair cognitive functioning. The routine rhythmic motion of running or walking, in particular, requires little thought or attention. Anyone who has run or walked regularly for even a few minutes knows how the mind seems to open to a flood of thoughts and emotions; solutions to nagging problems suddenly appear like flashing 100-watt bulbs. Fantasies arise. You find yourself thinking of all the smart things you should have said to the cop who gave you that speeding ticket. In fantasy, there’s no limit to your power and ability, and during that magical time, with the blood flowing and the legs pumping steadily, many people find the key to solving whatever problems plague them. It’s a creative, mentally stimulating time for many.

And for those who are troubled by depression, in particular, exercise may unlock the chains of their despair, or at least offer a break from it. Think of an exercise period as a sort of vacation from all the negative thinking and nagging sense of guilt or “what’s the use” that characterize depression. The benefits of this time-out reverberate long after the run or walk is over.