Vital Statistics : Modern medicine can give us all the information we could want--and more--about the state of our health.

Fitness can be a decidedly subjective affair. You run. You swim. You bike. No matter that your last complete physical was conducted by an unhappy looking, rubber-gloved doctor who pressed his way down a row of crouching, coughing teen-age boys to get to you. You’re fit, trim and built to last.

Maybe. But if you’re also honest, you have to admit that puffing up like an adder in front of the hallway mirror to show how fit you really are is hardly the stuff of science.

Fortunately, modern medicine has come a long way. Unfortunately, these advancements ensure that your fitness can be measured down to the last telltale triglyceride. You sign up for a complete fitness test.

You choose the California Heart Institute. A small area on the second floor of Ventura’s Community Memorial Hospital, the institute’s mission is the prevention and treatment of heart disease, no mean feat considering heart disease is still this nation’s No. 1 killer. Step one in this process is a comprehensive fitness analysis that could find warts on Adonis.

Your exam begins early in the morning, a propitious time considering the blood tests require you to fast for 12 hours. You are forced to skip only breakfast, probably a good thing anyway since breakfast usually consists of something high in sugar and low in nutritional value.

You opt not to share this tidbit. Medical people are finicky about diet and Linda Vrtis is no exception. Coordinator of the Heart Institute, Vrtis will shepherd you through the test. She is polite, professional and pleasant. Of course, she’s the one holding the needle.

She draws a test tube’s worth of blood and sends it off to the lab to be analyzed. She sends you off to the bathroom for a urine sample. Perhaps hoping to jump start your bladder, she tells you that you will have to remove your left shoe and sock when you return--this is where she will hook up the electrodes for your body-fat analysis.

And all goes well with the body-fat analysis, at least initially. A flick of a switch sends an undetectable current between electrodes attached at your ankle and wrist. Factoring your height and weight and blood pressure into a computer, Vrtis will arrive at an impedance figure--more to the point, the amount of body fat doing the impeding. Should impedance be higher than recommended, the same computer will prescribe an exercise plan and diet.

Finished impeding, you hike up your gym shorts and march down to the cardiac rehabilitation ward for a treadmill test. Up to now, the testing has been a breeze. Here in the cardiac rehabilitation ward, it will be machino a mano.

In preparation you are shaved and spotted with electrodes.

You look like a still. Which would be nice, because then you could pour yourself a drink. The treadmill sits gloating, secure in the knowledge that man hasn’t bested machine since John Henry outhammered the steam engine. And he had to die to win that one.

The treadmill starts up. Your heartbeat unravels neatly across the EKG screen. You look good. You should. You are walking at less than two miles an hour. Mall matrons move faster. The attending cardiologist, a witty fellow with a monogrammed stethoscope and a homey manner, instructs the nurses to bump the treadmill up a notch.

Ten minutes later you are running and sweating profusely. The cardiologist murmurs encouragement--”good, good, excellent”--undermining these soothing assurances with comments like, “The more stress we can give your heart, the more we can test for something potentially harmful.”

After 15 minutes your heart is thundering away at 174 beats a minute. Scientifically speaking, this is 92 percent of your maximal heart rate. Subjectively speaking, your heart is threatening to punch its way through your rib cage. The treadmill is switched off. You glance over at the EKG. The once smooth lines now look like something penned by a 4-year-old in fast-moving traffic. The cardiologist nods. You’re in good shape, he tells you.

You return to the physician five days later for your results. Your parts have been broken down into neat sheaves for computer printout; your sum, a small, gray folder.

The attending physician, a friendly but annoyingly fit looking fellow, scans the paperwork. The general consensus is good. Blood work is good. Cholesterol is low. Cardiovascular health is good. He pauses. There is one bit of bad news. Apparently 24% of you is body fat. Given your age (31), that puts you somewhere between Dom DeLuise and Jabba the Hutt.

You point out that this is odd. At 5 feet, 11 inches, 163 pounds your physique is often compared to cartoon characters and light posts. A double-check shows that the machine is malfunctioning. It is sent for repairs. You are hooked up to a second computer and impede another electric current.

The second opinion is better, but still not great. You are 19% body fat, still over the ideal for your age. In bold-face type it recommends you lose 8 to 15 pounds.

Later this seems petty. After all, the purpose of the testing is to help. Small matter if a dose of humility is part of the package. You have faced yourself. Objective and a little less than trim.

* THE PREMISE

* There are plenty of things you have never tried. Fun things, dangerous things, character-building things. The Reluctant Novice tries them for you and reports the results.

* This week’s Reluctant Novice is free-lance writer Ken McAlpine.