Efficiency, exercise, and the modern condition

January 18, 2010 | categories: energy, hard times | View Comments

Shortly after we bought our house, with its 500 ft2 lawn, one of my colleagues was kind enough to give me a vintage reel mower. It weighs 48 pounds. It was manufactured shortly after 1918, as dated by the patent on the cast handle, which I believe refers to this patent. It's very similar, but not quite identical, to this mower.

A modern reel mower of similar dimensions, like the Brill Razorcut, weighs around half as much. While I haven't actually used one, I imagine that it is substantially easier to push than my lovely behemoth. This brings us to the question of what I'm really trying to accomplish by mowing the lawn. Would it be better or worse if mowing the lawn were easier?

Here are my lawn-mowing goals: I want the grass to be uniformly short across the extents of the lawn. I want to avoid loud machinery, burning petrochemicals, and smelling like gas. I definitely want to avoid cutting my feet or otherwise hurting myself. If it's an unpleasant task, I'd like it to be quick.

At the same time that I'm looking for the best solution to that problem, I'm also trying to solve a larger problem, one endemic to the modern condition. As an educated American engineer, I spend most of my waking hours sitting at a desk, either manipulating a computer, talking to other engineers, or using a pencil. Perhaps 20% of my working time is spent on light physical work-- fabricating, assembling, or adjusting equipment. A very small fraction of my time-- less than 1%-- involves heavy work, like moving equipment or using hand tools. I see no reason that these divisions would change in future, unless I were to do still less manual labor.

Unfortunately, as a human, I die early if I don't live vigorously enough. We don't know the exact trade-off yet, but the data from the Framingham Heart Study, a longitudinal study of exercise and heart disease started in 1948, suggests that spending around 1 year of your life exercising (split into 30-minute daily stints) will extend your life by around 3.5 years, particularly if you're a good demographic match for Framingham, MA. Given that I grew up in a suburban Massachusetts town near route 495 much like Framingham, and I now live outside Boston, it's likely a great predictor for me.

My estimate of 1 year of exercise for 4 years more life is based on an analysis by Jonker, et al of the Framingham data in the journal Diabetes Care, put out by the American Diabetes Association. 2.25 hours of exercise per week, or 117 hours per year, puts you in their "high activity" group. That's about 8775 hours over a 75 year lifetime; there are 8760 hours in a year.

Since I don't have a time machine yet, I'm faced with the task of figuring out how to invest 2.25 hours per week in exercise, knowing that I'm likely to get a 4x return on the investment. (Maybe it's only a 3x return if I count the time I spend before or after exercise, like putting on sneakers or taking a shower. Still that's a huge return, especially given that it's paid in life, rather than in American dollars, which cannot be redeemed for life.)

So then the question is what goals I can accomplish using the 2.5 hours of vigorous activity I'd like to insert into my week. There are a few obvious candidates: shoveling snow in the winter and mowing the lawn in the summer. Strangely, due to the twisted incentives of the modern condition, I'd rather (or might as well) mow the lawn with a gargantuan, cast iron lawn mower than a light, nimble piece of German engineering. Our neighbors have been snowblowing our sidewalk as a friendly gesture, and I've found myself thinking, "But . . . you're taking away the only 30 minutes I've got in the winter where engaging myself in physical labor actually makes sense, and you're doing it with a two-stroke gas engine."

I am, however, not without recourse. I'm not lunkheaded enough to ask my neighbors not to snowblow our sidewalk, but this idea comes close. It's late, so the details will be saved for the next post.

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