Wednesday, May 21, 2008

Double Century Energy Intake/Output

My report on the Davis Double Century was pretty long, so I left out some details on what I ate. I still wanted to document it, so I am writing this as a supplemental report.

This event was clearly the largest/longest single output of energy I have done, most likely in my entire life. I have no objective measure of exactly how much energy I burned on that day. Some cyclists use a power meter to get an exact measure, but I do not have one.

Instead, I will estimate it based on the total amount of time I cycled and the average rate of energy usage for strenuous cycling. This is not very precise, but it gives a good estimate. I have read from various sources (like this one) that strenuous cycling for someone my weight (currently 158 pounds) burns roughly 600 to 800 calories per hour. I think 700 calories per hour is a reasonable estimate for my activity. I was coasting downhill part of the time, but was also putting out extra effort uphill part of the time.

If I use my full time-on-bike measure of 13 hours, I come up with a total of 9100 calories. This is in the same range as what other people reported, so this estimate should be close to the actual value.

Now to calculate the energy intake. I really ate a lot of food that day. Almost all of it is normally considered "junk" food, but on a day of extraordinary exertion, it really was "essential" food. I ate before I started, and I ate at each of the 10 stops I made on the route (although at the last stop I ate only one cookie).

The second rest stop and the wonderful food on display.
Cookies, crackers, fig newtons, bagels, cakes, packaged energy bars,
peanut butter / jelly, bread, and then fruit on the last far table.

I chose food based on how much energy it contained, how quickly it would digest, and sometimes if it had necessary minerals. This meant I ate large amounts of cookies, cakes, and potato chips. All three of these contain dense energy, and the chips has large amounts of sodium. At the lunch stop, I also ate a cheese sandwich and some oily pasta salad. I had started the day with a large donut. I ate pieces of orange and banana at regular intervals.

I made an estimate of how many calories I consumed:

1 apple fritter 800
12 oreo cookies 600
10 chocolate chip 600
4 pieces pound cake 600
handfuls potato chips 500
pasta salad 400
cheese sandwich 500
5 cans cola 750
2 oranges 150
2 bananas 200
Total 5100

Even though this is a large intake of food, it only accounts for just over half the energy that was burned. The rest needed to come from my body's energy stores.

I weighed myself Friday morning before work (I drove to Davis straight from the office) and I was 158 pounds. I weighed myself after returning on Sunday morning and I was 148. I had to stare at the scale for a while to be sure I was reading it properly. But, of course, most of the difference was due to water loss, not tissue loss. I was thirsty and hungry most of Sunday, and immediately got a few pounds back from eating and hydration.

One thing I did differently is that I did not drink just water, like I usually do. My boss, Joel, (himself a triathlete) recommended some electrolyte replacement tablets called Nuun. Since I had problems with dehydration on my last century, I decided to give it a try.

I carried two water bottles with me. I kept one as just pure water, and the other I filled with water and added a Nuun tablet. The Nuun has no calories (no carbohydrates). It is supposed to have a lime flavor, but to me it tasted more like tender coconut (which is actually an excellent natural source of electrolytes). I cannot say for sure that it made a difference, but I had no dehydration problems the whole day. Plus I had no cramping. I may continue to use it for rides that are long and hot.

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