You probably don't think twice (or even once) about the selection of "Fitness Master" topics and the structure to the articles. And why should you?

You read because you're interested in health and fitness, not because you're writing a review. But this week, understanding how and why I do what I do just might make you do something you probably need to.

Exercise more often.

The best "Fitness Master" topics appeal to a wide range of readers including those not so hardcore or hardworking. That's why you have yet to read about the British study conducted at Exeter University that found drinking beetroot juice before intense bicycling could improve race performance in the time trial up to 2 percent a reduction of 60 seconds if the race takes 50 minutes to complete.

Since many races and most competitive training require efforts similar to time trial efforts, this is helpful information for all who want to get better on the bicycle. And since the winners of time trials are often determined by far less than 60 seconds, this is a rather significant study for serious time trialists.

But there just aren't enough of either out there to warrant an 850-word article.

Subsequent research, however, has shown drinking beetroot juice also reduces the amount of oxygen needed to perform typical low-intensity exercise and that it increases blood flow in the brains of older adults. Reduced blood flow in the brain has been linked to all forms of senile dementia, including Alzheimer's disease.

As a result, the topic now takes on a broader appeal; therefore, an article about it is in the works.

The structure of a benefits-to-beetroot-juice article will be crucial to how many readers read more than the intro. Fill it with too much technical terminology, and the casual reader could abandon it midway.

Yet make it too general and it will either generate little interest or exclude essential information.

So why are you being asked to consider the selection and structure of "Fitness Master" articles? Because you're about to read about the benefits of exercise.

Again.

I checked my files. For the past few years, a benefits-of-exercise article has made it into print about as often as the change of seasons. Yet that doesn't mean I'm in need of topics.

It means that the evidence is accruing at a rapid rate. And that reading about the evidence provides justification for those who do exercise and motivation for those who don't.

Which means such an article even at a rate of four a year applies to everybody, but especially those who don't. And too many don't.

A phone poll published last September in the American Journal of Preventive Medicine found that only 5 percent of Americans work out vigorously during any given 24-hour period.

If you're part of the other 95 percent, here's what you need to do. Read the bulleted list of all the benefits found in the scientific studies released since the fall and try to write a logical argument for why you don't need to.

If you can do so, e-mail your reasons to me. I bet I can find flaws in them.

If you can't make a compelling argument for staying sedentary or just not exercising enough, concoct a plan that creates a way for you to work out at least four times a week for about 45 minutes.

And if you do regularly break a sweat four or five or six times a week, congratulations. Here are some of the good things that are happening as a result:

ŸAerobic exercisers are less likely to catch a cold. In fact, those studied over a 12-week period and exercised at least five times a week had 43 percent fewer days where they reported cold symptoms as opposed to those studied who worked out no more than one day a week.

ŸWalkers are more likely to retain full brain function. Senior citizens in a study who walked nine miles a week and were again studied nine years later were found to have retained greater gray-matter brain volume enough for researchers to report a twofold reduction in the risk of cognitive impairment.

ŸWeightlifters are less likely to have heart problems. That's because Appalachian State University researchers found that weightlifting reduces blood pressure levels even longer than aerobic exercise and that it increases blood flow to the limbs. Aerobic exercise, however, is more effective at reducing arterial stiffness.

ŸAerobic exercisers are less likely to have sleep problems even though researchers at Northwestern University are not sure why. What they do know is that 23 sedentary subjects who characterized themselves as having some sort of sleep problem improved their quality of sleep during a 16-week program where they either walked on a treadmill or peddled a stationary bike.

ŸLong-term male exercisers tested in a Swedish study were found to have double the oxygen intake as comparably aged sedentary subjects. In fact, the oxygen-intake levels recorded by these exercisers some as old as 90! are similar to those recorded by sedentary males 40 and 50 years younger.