Gym bunnies have another reason to feel smug: the energy they use to burn fat is being used to keep the lights on.

 

The Cadbury House gym in Congresbury near Bristol is thought to be the first in the world to install equipment that powers itself as well as the building.

 

It has spent around £600,000 on 42 new pieces of ARTIS Technogym equipment such as bikes, cross trainers and 'vario' machines that are hooked up to its own energy supply.

 

Once the user begins to exercise the equipment powers up and, after generating enough electricity to switch on the devices' displays, feeds the surplus into the building's energy supply.

 

Each produces enough electricity to light a 100W bulb, while brushless motor technology and low-friction materials reduce the treadmills' energy consumption by 30 per cent. Users can also connect to the machines using smart phones to track their training records.

 

The idea of using 'power from the people' is not entirely new: an outdoor gym in Hull has used the machinery to power LED lighting at the site since 2011.

 

Now the company that installed it, The Great Outdoor Gym Company, has kitted out Sir George Monoux College in Walthamstow with gym equipment that harnesses students' energy, charges their phones and sends the surplus energy back into the college.