Wednesday, January 24, 2007

Bad science, popularized

I just read about a recent study published in JAMA that details an apparently disturbing trend among high school football players: employing tremendous efforts in both the weightroom and at the training table in order to beef up to the magical 300lb mark, which will make them not only more effective players, but also more coveted objects for college recruiters.

Ambitious kids wanting to get better at something -- that sounds terrible.

Thanks to these kids' efforts to pack on the pounds, the study shows, 45% of them are now meeting "clinical standards" for being overweight, and 9% meet standards for severe adult obesity.

The study has sparked an outcry in the press, with concern over the deleterious health effects to which these high schoolers are exposing themselves in pursuit of their goals. After all -- what happens if they don't make college ball or the pros, and wind up being just behemoths without a cause? Or even if they do find success, think of the terrible health consequences of being so big! Arthritis, heart disease, diabetes, and the list goes on. The horror!

But then again, imagine if the authors of this study had used just one shred of scientific integrity or cogency in propogating this drivel.

The principle metric employed in the study is the Body Mass Index, or BMI. This tool, arrived at mathematically by dividing one's weight in kilograms by one's height in meters squared [kg/(m)^2], was designed to provide a numeric tool for classifying people of average (read: flabby) body composition. The tool was intended to be used for sedentary individuals -- i.e. people with minimal muscle mass. The blatant flaw in this metric is the lack of any accounting for actual body composition, in terms of the balance between fat, muscle, bone, and viscera. Consequently it becomes extremely inaccurate in people with either ectomorphic (slender) or mesomorphic (thick, muscular) frames.

Now given this flaw, you can use your imagination to think of the worst possible applications of this metric. Could we use it on Olympic gymnasts?, they drop off the bottom of the chart, because the metric was never intended to be used on them. But wait! -- on the other extreme, there's no limit to the abuse of statistics when we injudiciously apply the BMI to strength athletes! Sounds like a red letter day for piss-poor clinical research!

For example: take a look at these guys, from the 2002 Mr. Olympia contest. Each one has less than about 5 or 6% bodyfat. They are the very antithesis of obese. And yet, the winner of that contest, Mr. Ronnie Coleman, weighed in at 245 lbs for his 5'11" height -- for a BMI of 34.4. HE'S OBESE! HE'S OBESE! SOMEBODY CALL RICHARD SIMMONS!

So why, pray tell, would a group of seemingly intelligent scientists decide to use the BMI as a tool for assessing a group of high school football linemen -- guys who spend hours in the gym, packing MUSCLE onto their frames? You'd be hard pressed to preselect a group of people for whom your metric would be less appropriate.

Why not study the frequency and volume of their menses?

Why not study their gas mileage?

Why not compare their performance to the S&P 500?

The point I'm making here, in case it isn't painfully obvious, is that using the BMI on these guys is arrantly asinine. This is a catastrophic blunder in judgment, to use a purportedly scientific metric in such an injudicious fashion. And yet this study found publication in a journal of high repute with the public, and sparked a roar of controversy among the thoroughly uneducated press. After all, if a bunch of scientists applied this test and got these results, they must know what they're talking about, right?


Now I recognize that high school football players are growing bigger -- more muscular and fatter. But with a few exceptions, they are NOT obese. They are just big. So what. Will they have developed behaviors that will ultimately lead them to become obese, and to threaten their health when they are no longer athletes? Yeah, maybe. But why is that so unfathomable? Why is it becoming so hard to understand that success has its tradeoffs -- and that in most cases, the greater the success the larger the tradeoff employed in bringing it to fruition?

The press would rather have these kids wallow in mediocrity. Concerned health groups want them to eat 8 servings of fruits and vegetables and get 20 minutes a day of aerobic activity, to lead low stress lives and take Prozac if things get out of hand, and to always be mindful of their life expectancy. Well, you know, there's nothing wrong with that approach, per se, but it seems as if the principle societal pressure these days is for people to be average. We can't have our teenagers trying to get huge and become millionaire football players, because John Q. Public is already huge (but doesn't want to be) and is nowhere near being a millionaire (but desperately wants to be).

The way I look at it, I'm just glad to see these kids striving for something. They're not whittling away their lives with a Nintendo Wii joystick in their hands, and they're not in the parking lot smoking pot all afternoon. Good for them! I hope they succeed -- and if not, I hope they can find the tools to prevent the potential negative health consequences of their behavior in the future. But for now, the kids want to be great.

Let's let them try.