Why we hit the wall in marathons, and how not to.
My first marathon was the 1999 California International Marathon in Sacramento. As I trained for it, many of my friends who were marathon veterans gave me the usual warnings to “respect the distance,” pace myself conservatively, and avoid setting too ambitious a goal. I truly believed that I would heed this advice, but I did not. My 6:06 first mile felt so easy that I decided to forge ahead at that pace. Consequently, by the 18-mile mark I was walking. I finished in 3:34, after having run the first half in under 1:23.
My second marathon was the 2000 Long Beach Marathon. I truly believed I had learned my lesson and started at a slightly more conservative pace than I had in Sacramento, despite the fact that I was now fitter. But by the 23-mile mark I was again walking. I finished in 3:11, a scant 26 minutes off my goal time.
Not until I ran my third marathon did I run my first halfway decent one. I finished in 2:46:42 at the 2001 Rock n’ Roll San Diego Marathon. Yet while I did not fall apart in this race as I had in my first two marathons, I still slowed substantially in the closing 5K. My average pace over the first 23 miles was under 6:20 per mile, but my last mile was run in the range of 7:30.
If I have learned only one thing from the 14 marathons I have now run it’s that pacing oneself optimally in a marathon is very difficult. The only marathons in which I have not run the second half substantially slower than the first are the few I have run non-competitively, as workouts. I don’t have this problem at shorter distances. My pace is almost always metronomically steady in 5K’s, 10K’s, and half marathons, even on my bad days.
I am hardly unusual in this regard. The vast majority of experienced runners are able to pace themselves well in shorter events but bonk to some degree before they reach the finish line in marathons. For example, in the 2007 California International Marathon, only 24 of the top 100 finishers managed to run the second half of the race no worse than one minute slower than the first. By contrast, in the 2008 Carlsbad Half Marathon, only eight of the top 100 finishers slowed to a similar degree.
Why is pacing the marathon so much more difficult than pacing shorter races? And for that matter, considering the fact that even the winner of most marathons runs the first half slower than the second, can we even assume that maintaining an even pace throughout the entire race is the optimal marathon pacing strategy? What can we do to improve our marathon pacing? Let’s tackle these questions one by one.