Friday, January 20, 2006

The Negative Split

Kiera is out scrapbooking and the kids are down, so with some time on my hands I went to the computer to check on a statement I made to the guys at The Running Shop about my difficulties in the last six miles and my thoughts that half of those ahead of me probably went out smart and ran a negative split for the second half of my marathon last weekend. Luckily these guys know I'm full of crap, so when I saw how wrong I was when I analyzed the results I knew I didn't have to call them to correct myself.

These are rounded up or down by a few seconds for the sake of clarity.


The numbers above indicate how many minutes longer each of the 26 finishers ahead of me took to run the second half of their race compared to their first half. A zero indicates an even split and a * represents a negative split of that amount. The two 4 minute negative splits were the first two women in the race; In fact only two of the six even or negative split runners were men. And yes, some poor bastard ran a 23 minute positive split and still beat me or his results were screwed up.

To add insult to injury, the two Arizonans who beat me (and thus won $1000 and $500 respectively) ran a 4 minute and 15 minute positive split respectively (I promised Kiera I wouldn't grind my teeth anymore). I ran the second half 4 minutes slower.

Was the second half of the course that much more difficult? Tough question. Geb didn't seem to mind, since this "slower" half is where he cruised to his half-marathon world record. I'm sure the elevation chart can be trusted, and I do not doubt the accuracy of the course (overall).

Looking at thes results at Run Race Results, which show the 20 mile split, I see that I passed five people in the last six miles (see, I TOLD you I didn't imagine it), and I was clearly slowing down by this point. Is it simply a case of the "siren song" of the marathon, which causes all of us to go out too fast and run aground on the jagged reef that is mile 20, or is it merely the body saying "I've had enough" as the glycogen supply exhausts itself and our bodies shift to cannibalizing themselves, feeding on our own fat and muscle? Coach Pete Pfitzinger says to plan to run a one minute positive split, as even if you run the entire marathon at the same effort, the cardiac drift (heart rate elevation due to increased heat, internal and external) and deterioration in form and reduction in overall running efficiency will slow you down a little.

The multiple long runs Arthur Lydiard prescribes are designed to increase both the time and the speed at which you can run before you exhaust your glycogen supplies by increasing your efficiency. The anaerobic training that follows is designed to take you the rest of the way, when you finally do start to accumulate more lactic acid than you can clear. But my "quick-burn" of valuable fuel during my 5:44, 5:55, 5:49 starting miles helped hasten the shift from aerobic to anaerobic, and no doubt contributed to me ending up on the wrong side of the statistics.

This is just one of many lessons from my race, and while I'm not beating myself up or taking the fact that I reached my first goal for granted, this is a necessary step to reaching higher next time.


The Last Runner said...

You ran a PR Mike. That is what counts.

Yeah you should have gone out slower but ultimately you ran your goal time (under 2:40).

You have more room to improve. Stick to your program and you'll run faster. Heck, choose a flat sea level course the next time. You might shock yourself and us.

Joe said...

Mike, I just discoveed your blog and added it to my list. Fascinating reading your app;ication of Lydiard to your running. Mega-congrats on your awesome sub 2:40! I really enjoyed the write up. Well written. I would ever only DREAM of spending any time with the lead women's pack!!

Dallen said...

I think those splits are are the norm for most quick runners. Only a select few manage to go negative. A negative of even split requires perfect execution, an incredible pain tolerance, or usually means going out too slow and not acheiving potential.