years? Exercise, say the experts, and do it at least three times a week.

A study conducted at Scripps College in California suggests that regular exercise boosts mental dexterity.

The researchers place 300 men and women between the ages of 51 and 91 into groups based on an assessment of their health and whether or not they exercised regularly. Then they studied in detail the 62 most active and the 62 least active.

Those who engaged in regular physical activity consistently outperformed the sedentary subjects on tests of mental abilities.

They recalled letters flashed on screen 36 percent more often than the couch potatoes. They performed 22 percent better on written tests on reasoning ability. And they reacted quicker when typing in numbers appearing randomly on a computer screen.

The study also indicated that regular physical activity rather than general health status accounted for the better mental performances. The people who exercised consistently performed better regardless of whether or not they had health problems.

COMPETITIVE CYCLING -- Exercise helps you keep mentally alert and physically fit. Experts recommend that you perform some type of aerobic activity at least three times a week.