ALBANY, N.Y. We all know exercise is good for your heart, but few of us think about the benefits exercise has on your brain, or, for that matter, your endocrine system.

But research shows that regular physical activity stimulates hormones throughout the body, helping maintain your bodys sense of equilibrium and well-being.

In addition to all the other benefits of fitness, exercise has the power to keep your bodys hormones in balance, particularly insulin, said Dr. Gregg Gerety, an endocrinologist here.

During physical activity, a number of hormones come into play, Gerety said. First, theres the stress hormones, or catecholamine class, including epinephrine or adrenaline norepinephrine and cortisol, which help prepare the body to meet challenges. Also called the fight or flight hormones, these adrenal chemicals give you a boost of energy and help your body deal with the physical strain of exercise, Gerety said.

Insulin is another hormone that responds to exercise. This hormone is produced in the pancreas and controls metabolism. Insulin isnt released in response to exercise, however it does fall a little, and lower insulin levels may help patients lose weight.

This is because insulin causes the body to use glucose from the blood; when insulin levels are low, the body turns fat into energy for the cells.

In diabetes patients, the body isnt able to control its own insulin levels, and often must resort to external applications of insulin. Aerobic exercise has been found to be extremely good for diabetes patients because it helps them become more sensitive to their own insulin levels, Gerety said. He prescribes about 30 minutes of cardio a day, five times a week, to help control diabetes.

Exercise also stimulates the enkephalins, or endorphins. These feel-good chemicals are natural hormones the body makes in response to exercise, Gerety said. As a result, exercise produces a subtle yet pronounced sense of euphoria that keeps us coming back for more, Gerety said.

According to the Mayo Clinic, exercise can help treat depression and anxiety, and research suggests that it is because it boosts these feel-good chemicals, the bodys natural mood-enhancers. Exercise also helps reduce cortisol levels, which could be another factor in the fight against depression.

Testosterone, the male hormone, also contributes to a sense of well-being and helps build muscle mass.

A lack of any of these hormones could make exercise very difficult for people, says Gerety. They might have no interest in exercise, or tire very easily during their workout. This inertia or lassitude can lead to weight gain, and in turn, other health problems. If you suspect a hormone condition, Gerety advised, bring it to the attention of your primary care physician. He or she may prescribe testing, including checking thyroid function, testosterone levels, diabetes testing and perhaps even cortisol levels. Depending on the results, you may need to consult with an endocrinologist, he said.