Human power

Human power is work or energy that is produced from the human body. It can also refer to the power (rate of work per time) of a human. Power comes primarily from muscles, but body heat is also used to do work like warming shelters, food, or other humans.

World records of power performance by humans are of interest to work planners and work-process engineers. The average level of human power that can be maintained over a certain duration of time, say over the extent of one minute or one hour is interesting to engineers designing work operations in industry. Human power is sometimes used to generate electricity that is stored.

Normal human metabolism produces heat at a basal metabolic rate of around 80 watts.

A trained cyclist can produce about 400 watts of mechanical power for an hour or more, but adults of good average fitness average between 50 and 150 watts for an hour of vigorous exercise. A healthy well-fed laborer over the course of an 8-hour work shift can sustain an average output of about 75 watts. The yield of electric power is decreased by the inefficiency of the human-powered generator, since all real generators will incur some losses during the energy conversion process.

While some exercise equipment has been fitted with generators, the amount of energy collected is of low value compared to the cost of the conversion equipment.

Several forms of transport utilize human power. They include the bicycle, wheelchair, walking, skateboard, wheelbarrow, rowing, skis, and rickshaw. Some forms may utilize more than one person. The historical galley was propelled by freemen or citizens in ancient times, and by slaves captured by pirates in more recent times. The Gossamer Condor was the first human-powered aircraft capable of controlled and sustained flight, making its first flight in 1977. In 2007, Jason Lewis of Expedition 360 became the first person to circumnavigate the globe using only human power: walking, biking, and rollerblading across the landmasses; and swimming, kayaking, rowing, and using a 26-foot-long pedal-powered boat to cross the oceans.

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