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Three years ago I posted an article called “The Efficiency of the Human Body”, and it has proven to be popular. Then I posted an update last November. I’ve now learned more about the subject, and thought about it, and it’s time for another upgrade. Naturally, upgrades almost always involve an expansion, so there are two pieces now: This one, which explores the distribution of energy use in the resting body (our resting metabolic rate) and the next, which includes the material in the original post by describing energy distribution in the body in motion.… Read the rest “Human Energy Metabolism I: The Body at Rest”

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Nutritional scientists break down energy consumption into three components. The largest is Resting Energy Expenditure (REE), which I’ve examined in detail in the previous post. It accounts for 60-80% of our daily energy consumption. REE is the energy consumed at rest, when there’s no physical activity going on. Another 5-10% is used for digestion. The rest of our energy consumption is due to physical activity. These proportions can vary: if you’re a rider in the Tour de France, your daily physical activity will probably exceed your REE several times over.… Read the rest “Human Energy Metabolism II: The Body in motion”

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The material in this post has been upgraded and expanded in two posts, which describe human energy efficiency at rest and during vigorous exercise.

I first posted “The Inefficiency of Humans” in January 2017. It’s about the reasons that our energy metabolism provides only about 20-25% of the energy we consume as food for muscular work. I referred to this as our “inefficiency”, although it isn’t really that. The explanation and conclusions remain largely unchanged, but since then I’ve learned more about how energy metabolism is measured, so I’ve rewritten the post as this 2.0 version.… Read the rest “The Inefficiency of Humans”

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Jesse Owens starting the 200 meter race at the 1936 Olympics. Reproduction of photograph in “Die Olympischen Spiele, 1936” p.27, 1936. 

Coverage of the recent victory of the New Zealand team in the America’s Cup yacht race featured sailboats flying along on their underwater foils at ridiculous speed, speeds reaching more than 50 miles (80 km) per hour. Whether it’s running, or driving a car, or sailing these mutant boats, speed is exciting.Read the rest “Speed Limits”