Yes! I've thought about that exact same thing!

It would be a cool marketing gimmick, too. Call the gym something like "Watt's Gym", and add card readers to each machine so people can track their total produced killowatt-hours.

The actual amount of energy generated would still be pretty small, but it would be a fun gimmick to motivate people.

You could have an app and little screens showing the total energy that you generated this session or month, and see how much energy you contributed to the total for the whole gym that period.

Heck, an average workout could generate maybe 0.03-0.04kWh and if the gym was popular enough that would add up to a portion of the electricity used by the facility.

Those savings could even be passed on to the members with a reward system of some type, which also works as a marketing/motivational gimmick.

The thing would be to have a global counter per row or room, 0.04kWh seems ridiculous but if you get 10-20 people putting 1kW it starts to get impressive. I also wanted to couple that to shelter so homeless people could warm up food or water etc.

You get free sport and they get a slightly better life..

ps: if you ever set something like that up, please share the plans :)

Just a small step towards turning humans into batteries like in the Matrix.