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An electric workout through pedal power

Gyms hook up exercise bikes to TVs, laptops, and batteries to let their patrons power the place.

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Elliptical trainers, another popular piece of cardio equipment, are a good source of human power.

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“They are even better than bikes since they involve both arm and leg muscles,” says Hudson Harr, founder of ReRev.com in St. Petersburg, Fla. In April, his start-up company installed an array of retrofitted ellipticals at the 28,000-member Gainesville (Fla.) Health & Fitness Center. A student gym at the University of Florida in Gainesville was next on his list. “Not doing this would be such a waste of energy,” says David Bowles, the school’s director of recreational sports.

How to balance the workout
The idea of using human energy to power appliances – instead of using batteries – is catching on for two reasons: fun and environment-consciousness, says Arjen Jansen, a researcher in human-powered energy systems at Delft University of Technology in the Netherlands.

“Laptops and televisions have evolved and the designs are very energy-efficient, says Jason Moore, a Fulbright scholar studying bicycle design at the Dutch university. Now that these rigs are better at capturing energy, gyms are can put them to use – powering little perks such as TVs, laptops, and lights.

Still, few people go to a fitness center in order to generate electricity.

“People go the gym primarily to get a good workout,” says Whelan from Green Revolution. The workout equipment should feel just like it did before the retrofitting, he emphasizes. Raising the resistance level on these machines will increase the output exponentially, but it might ruin the experience for his customers. He opts to let the rider have complete control over the settings, same as before.

What’s next for ecogyms?
“What we are doing now is taking baby steps in the right direction,” says Boesel of Green Microgym.

All aerobic equipment, including Stairmasters and rowing machines, can be retrofitted to generate power. Each device, however, comes with its own set of engineering challenges. And while the industry is most driven by retrofitting companies, “in the future, manufacturers may offer power-generation as an option on cardio equipment,” says Joe Cirulli, owner of the Gainesville Health & Fitness Center.

Some energy savings could be incidental. “As the exerciser’s output exceeds the display needs, the extra power is ‘shunted’ to resistors, which then heat up simply to shed the energy that is created,” says Mr. Taggett of Team Dynamo. The cardio room warms up and requires extra air-conditioning in warmer climates. With these new machines, however, the excess energy is channeled into creating power.

As exercisers become aware of the metrics of human power-production, it could push them to work harder.

“What we have been finding is that people challenge themselves to work a little bit harder because now they can measure how much energy they create,” says Whelan. “It seems like there is a personal goal to try and create just a little bit more than the last time they worked out.”

When they gravitate to these innovative systems, gym-goers could also move away from power-hogging equipment. Once people figure out that the average treadmill takes 1,500-2,000 watts to run, they may switch to power-producing machines, says Taggett.

“Right now, it would take nine Lance Armstrongs or 15 nonathletes to keep one treadmill chugging along,” he says.

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