CHICAGO -- What weights do for your muscles, the exercises on mybraintrainer.com supposedly do for your brain.

"You're training your brain to be better and better," said Mike Haley, who is with American Eagle, the company that developed the site.

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The test is available at www.MyBrainTrainer.com.

For more information on staying sharp from the American Association of Retired Persons, go to www.AARP.org/health/brain and www.DANA.org/braincenter.

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The owners call mybraintrainer.com a gym for your brain, designed to try to boost your brainpower.

American Eagle's Erick Robertson said that most people don't take time to work out their brains.

"It's a relatively recent phenomenon," he said.

To find out if it really works, NBC5 asked some people who appeared to be already pretty smart to test their brain's age -- a 44-year-old member of MENSA, a 60-something retired teacher, and a 25-year-old student in his fourth year of medical school.

"I was 56. Since I'm 44, I don't think I want to be that old," said MENSA member Stacey Kirsch.

Pennie Machnick, a retired teacher, was a bit worried going into the test.

"I thought, 'I'm going to find out I'm 105 years old,'" she said.

Jay Shah, the medical student at Rush, got some disappointing news.

"Embarassingly, 50," he said.

Suffice it to say the test got all three interested in giving the exercises on the Web site a try.

"There's speed, there's accuracy, concentration -- all make up what your scores are in your brain age," said Robertson.

The exercises are repetitious actions that work out specific areas of your brain. The developers call them your "mental reflexes."

Robertson put it like this: Imagine the skill a baseball player needs to discern, in a split second, what type of pitch is coming at him. This sort of brain exercise could help, he said.

"To be able to train his brain to be able to respond faster to what he sees is a big advantage," Robertson said.

But can it improve your memory or prevent something like Alzheimer's disease? NBC5 asked Sandra Weintraub, a professor at Northwestern Memorial Hospital's Alzhiemer's disease center.

"Memory and aging and cognitive functions are incredibly complicated, and so to think that you're going to boil it down to a simple little test on a computer, I think is not realistic," she said.

However, Weintraub said that doesn't mean the exercises don't have value.

"There's something to be said about practice. It can speed things up," she said. "If you do something over and over again, chances are fairly good you're going to speed up."

Shah, the medical student, said he found the exercises to be fun.

After a week of mental workouts, NBC5 checked back in with the panel. Overall, the reviews were good.

Machnick said that she liked how the site explained particular parts of the brain that certain exercises are supposed to help.

Kirsch also liked the mental workouts.

"Each test takes only a minute or so, but then you get addicted and you kind of want to do more of them," she said.

But did their brain workouts improve their brain age?

"The very first time I took it I was 56, and now I'm 38," Kirsch said.

"My brain age was 34. I guess I lost 16 years in the last week," Machnick said excitedly.

Shah said he lowered his brain age by six years younger than his real age.