"I might not be able to define it, but I certainly know it when I see it." Years ago, when a lawyer demanded a definition of pornography in a court of law, that's supposedly what Supreme Court Justice Potter Stewart said.

I often borrow those words when I'm asked to define something far different.

Excellence.

Sure, I can tell you exactly what makes a meal or a workout excellent if your goal is health and fitness, and the same is true for a novel or a newspaper column, but there's no way I can express what makes one song so much better than the other.

It's too visceral. I just know it when I hear it.

Similarly, I don't always know what makes excellence in certain sports, especially those in which I've never participated.

Like any sport performed on ice skates.

I have never been on ice skates in my life, but back in 1980 during the Winter Olympics, I was glued to the TV anytime Eric Heiden competed.

That guy won all the gold medals in speed skating that year a total of five and at such different distances that it's analogous to a track and field runner winning the Olympic gold in the 200-, the 400-, the 800-, the 1600-, and the 5000-meter events.

Talk about dominance, talk about excellence and talk about my surprise and delight when Eric Heiden decided to change sports and race bikes.

I just had to see the man in action, so I attended a criterium he was supposed to do in Doylestown in 1985. Yet I was psyched when his team, sponsored by 7-Eleven, decided at the last minute to pull him from the race.

A criterium is a course of no more than a mile or so usually repeated at the pro level 50 or more times. So the course was easy to walk, the crowd was sparse, and I found Heiden in no time.

But I never spoke to him.

I just looked in awe at his shaved, tanned, and freakish 30-inch thighs, imagining the power that those beasts could produce pressing down on bicycle pedals.

Back in 1980, I had heard the Olympic announcers mention that measurement and just assumed it was exaggerated, much like a basketball player's height. After all, my waist was only a fraction wider than 30 inches.

But here I was, here he was, and oh my God! those announcers were right. My waist really was actually equivalent to one of his thighs.

So why the trip down memory lane? Because Heiden and I share something in common now and it's not the size of a single body part.

Heiden writes a health-and-fitness column that's carried on Tuesdays in The Morning Call, and I can't get the one from October 26 out of my mind. It's about how your body weight is not a good measure of your health and fitness.

Heiden's a doctor now, for goodness sake, and this is hardly earth-shattering news. Worse, he suggests using a measurement that I totally pooh-pooh: the BMI or Body Mass Index.

The problem with the BMI is that it's nothing more than a relationship between your height and your weight. That means, for example, just about every professional football offensive and defensive back guys who carry as little body fat as many professional bodybuilders is found to be overweight according to the BMI.

Some are even so muscular that they are classified as obese.

But the new news that Heiden should have written about is that the limitation on the BMI works the other way.

Someone who is sedentary and carries little muscle mass as a result can be found to be at a healthy weight even though that person carries so much body fat that it compromises his or her health. In fact, based on research performed at the Mayo Clinic, it is now estimated that up to 30 million Americans register "healthy" numbers by the bathroom scale or the BMI yet are clinically obese and therefore are facing a whole host of potential health problems.

Does this mean that you need to race out and have your body fat percentage done?

While it wouldn't hurt because it's the best way to monitor the progress of either a new diet or a weightlifting regiment, there is another old-school option: from time to time get naked and look at yourself in front of a full-length mirror.

The mirror won't lie. If you're carrying too much weight around the hips and abdomen, the places where excess body fat leads to an increased risk of disease, it will be painfully evident.

And if you're really working hard at the gym, you'll see evidence of that, too. It's pretty easy to spot a loss of body fat or a gain of muscle mass.

A great body fat percentage for an active male to have, for example, is about 10 percent. You'll know if you're there if you see definition when you contract the abdominal muscles. The more detailed the definition, the lower the body fat percentage.