The Gym – a Potential Energy Source

I recently began to visit the Gym. Have spent a few minutes on the 'cycle' and the 'treadmill' ... and even pulling some weight around !!

What I was wondering is …

so much of potential 'physical' energy is utilized by humans in their gym visits everyday. So much energy is spent on the cycle, the stepper and the host of the equipment out there

Isn't there some way to harness this energy conversion and utilize the mechanical movement of the equipment to generate some amount of electricity or energy …

So much cycling, pulling, pushing, lifting of weights, running etc is happening in the millions of the gym's across the globe where we humans are trying to burn off the calories (energy) which is stored in our body but not consumed !

Is any Gym equipment manufacturer thinking of this possibility of harnessing this source of energy generation?

Something which could be used as a small energy source for the Gym itself thereby helping it decrease its own power bill !