Technical Info:

Watts are a common measurement of power output, like horsepower. One horsepower is equivalent to 746 watts. A person in decent shape can produce at rates of 60 to 120 watts during an hour of strenuous exercise. An elite cyclist can average 300-400! If a person averages 75 watts (about one-tenth of a horsepower) for an hour they will have produced 75 watt hours (Wh) of energy.

The generator we use is about 70% efficient so the actual electrical power out is 30% lower than the person's output. Humans convert food energy (measured in calories) into chemical energy that is used by moving muscles. The body is about 20% efficient meaning that only 20% of the food energy is turned into available chemical energy. The rest is lost as heat. What do you think keeps the blood at 98.6 degrees F (37 C) ?

A watt hour of human power output consumes roughly four calories of food energy. So, if you are exercising at a rate of 100 watts and you exercise for an hour (100 watt hours) you will burn 400 calories."