age-invariant versus life-course conceptions of marathoning

I used some very bad words when this email arrived in advance of today's Twin Cities Marathon:

TNT's critically acclaimed, hit drama, MEN OF A CERTAIN AGE, is back for a second season December 6th at 10/9c! In celebration of the highly anticipated return of this viewer-favorite show, TNT is assembling the "Team Of A Certain Age" at the 2010 Medtronic Twin Cities Marathon. MEN OF A CERTAIN AGE, touting an award-winning cast of Ray Romano, Scott Bakula, and Andre Braugher, provides a wry and realistic depiction of three friends navigating through the complexities of mid-life. This series proves that life is a marathon (not a sprint)! Now TNT is looking for men and/or women over the age of 40 to join our Team of a Certain Age! If you sign up and are selected, you will receive an exciting gift package valued at over $100, including:
* A high-quality Limited Edition running shirt to wear during the marathon;
* Six Limited Edition, customizable t-shirts for your friends and family, and;
* A $50 gift card to help reimburse you for the cost of your entry fee!

I've got nothing against the show, though my job as a department chair provides more than enough "wry and realistic depictions of friends navigating through the complexities of midlife," thank you. No, I just hate the idea of being targeted by age. Apparently, other dudes agreed. I saw exactly one runner flying the high-quality Limited Edition "Men of a Certain Age" shirt -- and that runner, my friends, was a young woman. Some clever curmudgeon pocketed the gift card and gave the shirt to his kid.

I realize that we all slow down, but part of me needs to believe that I could still crank out a personal record under the right conditions -- you know, during a sabbatical year, after altitude training, with perfect race day weather, while wearing a jet-pack. I mean, it isn't as though I was ever fast in the first place. So, I cling to the idea that my times are age-invariant -- I should be able to go as fast or faster than I ever have. To provide a reality check, I plotted my 25 known marathon times from 1995-2010. I don't yet have my official "chip time" for today, but it was 3:47 on the clock and I'm guessing it took at least 3 minutes to make my way to the starting gate.

Well, a few heat-induced clinkers spiked up in 2006-2007, but at least it doesn't look like a linear decline or the inexorable aging of the organism -- the correlation is only .0004 between age and finish times. I can see three slopes here: decline in my mid-thirties; ascent in my late-thirties, and another more gradual decline since my early forties. Looking at the graph, though, I'm still about as fast (that is, about as slow) as I was 15 years ago.

Next, I plotted something more life-coursey -- my percentile rank against Ray Romano, Scott Bakula, Andre Braugher and the other men of my certain age, pitting me against the male 30-35 year olds in 1995 and the male 45-49 year olds today.

This graph looks a bit better, though I was disappointed to find myself in the bottom half of my reference group during my early thirties (what the heck was going on? oh yeah, tenure and small children were going on...). But the percentile rank has the virtue of controlling to some extent for race conditions (everybody slows down in the heat) as well as life course stage. So, today I ran the full race with a M45-49 tag on my back. I'm still a long way from the prize money, but the equation says I'm picking up 1.5% per year.
By the time I hit M70-74, that sweet age group cash is mine.