It sounds like something you'd only see on the Discovery Channel: people pedaling ferociously to create enough energy to power the television, stereo and lights.
But for Adam Boesel, owner of the Green Microgym in Portland, Ore., and his partners, this could be the future.
Launched last week, his "human-powered" gym is one of few fitness centers in the world that runs on power generated by people working out, Boesel said.
As members pedal on stationary bicycles, a small motor connected to the stations charges batteries that power the gym's television and stereo system.
Boesel said he doesn't yet have a way to quantify the output but knows that at the moment it's relatively small. However, this is just the beginning, he said.
"Our goal is to someday create 100 percent of the electricity we use in the gym," Boesel said. "The short-term goal is to get all of the electricity we can out of the machines."
In addition to three spin bikes Boesel re-engineered the gym features a new four-person machine that generates 200 to 400 watts of electricity an hour, depending on the fitness level of the group.
Created by El Paso, Texas-based Henry Works, the Team Dynamo connects hand cranks and foot pedals to a generator to capture as much human energy as possible.
"It's a little humbling -- a person can make about a penny's worth of electricity an hour. So it's not a lot," said Michael Tagget, president of Henry Works, adding that on his or her own, an individual can create 50 to 100 watts of electricity.
"But if 20, 30, 40 people are doing that in a gym, they can [create] all the electricity for entertainment systems. It's better than nothing and the feeling of accomplishing something is worthwhile," Tagget noted.
Although Tagget's company is starting with the commercial market -- the Green Microgym is the first gym to test the product -- it plans to offer a home unit in the spring.
Boesel's gym is also working with a St. Petersburg, Fla.-based startup called ReRev.com to implement a "grid-tie" system. Instead of using a battery-based system, ReRev.com's approach is to retrofit elliptical machines to harvest energy from the machines and send the electricity directly back into the electrical panel.
Harr said his system is an improvement over battery-based approaches that require more maintenance and are less energy efficient. As energy passes through the battery, he said, some of it is lost.
ReRev.com retrofitted 15 machines at a Gainesville, Fla., fitness center in April and, Harr said, on average, that installation is producing between 2 and 7 kilowatts per day.
Although the Portland gym is one of the first facilities in the country to harness human energy, the technology has already been introduced in other parts of the world.
The California Fitness gym in Hong Kong uses a battery-based system to help supply power. The Sustainable Dance Club in Rotterdam, Netherlands, also relies on human-powered technology.