10 Innovations That Changed the Way We Exercise

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The Treadmill

Its namesake is a mill operated by a person or animal treading the steps of a wheel to grind grain. And the physical labor continued through the years: Prisoners sometimes walked early treadmills in 19th-century England and in New York at the Bellevue Penitentiary, where they generating power. By the 1960s, research by Kenneth Cooper led to the idea that the treadmill could be an important tool for aerobic exercise. Today, some treadmills have returned to their roots as sources of power. Gyms like the Green Microgym of Portland offer treadmills that harness the power of walkers and runners to generate electricity.