Thirty years ago, when I was running my best, I never ran a great marathon and why that was has always been a puzzle. I hate unsolved puzzles.
While training for a marathon, I ran a 32 minute 10K and a 1:10 1/2-marathon, so I was pretty sure I could break 2:30 in the marathon. I ran an even 5:30 pace, died at 15 miles and struggled in in the low 2:40's. Perhaps I wasn't in that kind of shape, so I ran 6's - and died at 17 miles, finishing in the 2:40's. The pace I needed to run to not hit the wall was about 7:10 (about 3:10 finish time), which was about my training pace at the time.
There was obviously something wrong with my training, so I got every training schedule ever devised and the one thing they had in common was that I couldn't do ANY of the workouts. If I scaled them back to where I could do them, they came out to 3:10 marathons. Either I was already the world's greatest overachiever (though the 32 minute 10K said not), or there was something very weird happening.
I assumed I just wasn't meant to run marathons and stopped doing them for 20 years. Top marathoners have about 90-95% slow-twitch muscle fibers and I have about half that, so I had a ready excuse - except I shouldn't be able to run a fast 1/2-marathon, yet I had.
When I turned 40, I decided to try to break 3 hours again and used all the information I had learned over the years. Knowing hat I could run far and run fast, but not run fast very far, I concentrated on long runs at marathon pace. Anything 25K or beyond at that pace was so close to a race for me that it would take 2-3 weeks to recover, but I found 1/2-marathons every other week and ran them in a comfortable 1:27-1:28 (one in a too-fast 1:24), but was worried that perhaps I wasn't in the shape I thought and was actually racing the half's, so I ran a 10K race in 36:54 and knew I had plenty left. I tapered for two weeks, did standard carbohydrate-loading and when race day came... I died at 8 miles.
There were a dozen reasons that could've happened, including lack of sleep from race anxiety, but the puzzle remained. For about the 30th time, I think I might have the answer.
My Dog Didn't Bite You, That's Just Slobber"
12 hours ago