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September 03, 2005
2:20:07/160
This concludes 7 days without a day off, during which I've run about 95 km (59 mi) in about 7 hours. My actuals show the times. I also biked, but only for 1:33:41, since I only took the train Monday and Wednesday.
Dana's done better than that. If I recall correctly, he's done 70 mi (almost 113 km) in a single week. I don't intend to match his record soon.
Today I went out before eating breakfast, because Nathalie needed me back here by 10 am. She's working at the Barraux library this morning. Although I had sports drink during the run, I started hitting the wall about 2 hours into the 30 km jog. The last 5 km were tough.
At the end, I kept thinking about men and women who finish 90 km -- which took me a week -- in one day at the Comrades Marathon. Kind of puts my dinky little standard marathon training plan in perspective.
Here's how much weight I lose temporarily on a 30 km jog. When I got up, I weighed 82.3 kg. Before and during the run, I drank approx. 2 liters of water with about 80 g of sports drink mix. After the run, I weighed 80.3 kg. If you figure I burn about 80 kcal/km, that's about 2400 kcal. Let's assume 1/3 come from fat (about 90 g) and 2/3 from carbohydrates (400 g), so that's a total of 90 + 400 - 80 = 410 g of weight loss that isn't water, or about 3 1/2 liters of water loss. Roughly a gallon.
Most of that ended up in my socks. My feet looked like they'd been taking a long bath. Some of it's still on the seat of my car where the towel got pushed aside.
Posted by Mark at September 3, 2005 10:18 AM
Comments
For comparison of estimates of calorie use in running, my old chart from Consumers Report says the following:
For a 180 lb (81.5 kg) runner, it takes (rounded to nearest calorie) 140 calories per mile (87 calories per km)at a 7:30/mile (4:40/km)pace and 130 calories per mile (81 calories per km)at a 12:00/mile (7:25/km)pace. Looking at the chart, you can usually add or subtract 8 calories for every 10 pound difference in weight. Walking at 4.5 miles per hour (that's 13:20/mile, extremely fast walking) you use 82% as many calories per mile as running at a 7:30/mile pace.
It looks like the estimate based on the Consumer report chart runs about 8% higher than your estimate. If your 30 km distance was an accurate measure, I get a 7:32/mile pace for your run today. My chart estimates you used 2604 calories.
Posted by: Dana at September 3, 2005 07:55 PM
My estimate of the water weight loss is probably about right, then. Even if all 204 extra calories came from carbohydrate, that's only 51 g.
I might be wrong about the number of liters sweat however. I wonder how much water gets pushed out with breath. Probably a fair amount if you're breathing hard for over 2 hours.
Posted by: Mark at September 4, 2005 05:13 PM