Apart from increasing the oxygen supply to the brain, exercise may also slow down the loss of dopamine in the brain. Dopamine is a neurotransmitter that helps to prevent the shaking and stiffness that can come with old age. A severe shortage of dopamine results in the exaggerated tremors of Parkinson's disease. Dopamine decreases in the brain by about one percent a year from our mid-20s, and if we lived to be a 100 years old, we would all appear to have Parkinson's disease. Since exercise can slow down dopamine loss, it is particularly beneficial as we grow older.
Exercise can also prevent our reaction times from slowing down.
Experts think exercise helps because it raises blood levels of endorphins. They are involved in the body's positive response to stress. The mood-heightening effect can last for several hours, according to some endocrinologists. These 'feel-good' biochemicals drop off when estrogen is low. Endorphins also play a role in the body's ability to regulate temperature.