Monday, May 08, 2006

Burning Fat (or What's that Smell?)

Depleted is the word for the day. 21 miles this morning on tired legs from yesterday's 13 miles, which included a tough 10K. With Kiera out of town for half of last week I didn't get in a long run, so I had to make up for it today. I had no desire (or ability) to run fast, so the goal was just to put the time on my feet in.

Duncan wrote about a "depletion"-style run recently, though in his case he fasted beforehand in an effort to simulate the last part of the marathon. I find that my body, like many others, can go close to 2 hours on my regular diet before I feel that shift from burning primarily carbohydrate to burning increased amounts of fat when my glycogen levels get low. While I'm not up to Duncan's challenge of fasting, a tough race the day before brought me into this run a bit depleted from the get-go. My rules were simple-no gels, no gatorade, 20 miles or more.

In the past, including my first go-around with Lydiard-based training, I've brought along a gel or two to make the last half of these runs more pleasant. After talking with Nobby, as well as reading more about glycogen depletion in books, this article on Greg McMillan's site, and this article reprinted on marathonguide from the Marathon and Beyond magazine, I've stopped.

I need to get used to the uncomfortable shift in energy systems and this is one way to do it. One benefit of long runs without caloric aid is that the body learns. Lets face it, what body wants to suffer that hollow, bonking feeling? My hope is that these kinds of runs teach my body to use stored glycogen more slowly by tapping into fat stores earlier. This, combined with carbo-loading to increase available glycogen stores before the race and taking carbohydrates and sugars on board during the race (gels and sportsdrink) will hopefully get me to the finish line with fuel in the tank.

Today was tough from about an hour and 45 minutes on, but I just kept trudging along at 7:18 pace. Hopefully next time it will be a little easier.

Training: 21 miles, 2:33:23, 7:18 pace
Last week: 72 measly miles in 9 sessions


tb1 said...

Congratulations on your 10K. I like your comment about making the body push back. BTW 72 "measly" miles would be a career week for me. I'm into my longest mileage week of this training session; 56 miles. Now that's measly! I'm looking forward to SD and the sound of 40,000 sneakers hitting the pavement.

edinburghrunner said...

Tough shift after the 10k - no wonder the last bit hurt.

Duncan Larkin said...

Anytime you are dragging on a long run like this--especially after a tough 10k--you are training and doing something in the right direction.