Tapping Salman Khan’s energy

I have a question to ask. Is it possible to have a gym where the mechanical energy created by folks who do exercises, is converted to some useful form, like say electrical?

When the train was still running, through the window, I saw a majdoor standing near the railway track, down below, brushing his teeth. He had a nice well built body. In fact the built was so good with all those biceps and triceps and six-packs and all that, that he reminded me of Salman Khan. And then I asked myself: to maintain the kind of physique that this majdoor has, he works. He probably moves bricks from one place to another, 10 hours a day or who knows, even more! He generates mechanical energy which gets utlized and he gets paid for it. So, can Salman Khan be convinced to utilize his mechanical energy than just let it go?

Now Sallu might say that he doesn’t have 10 hours in a day to move bricks. He might say that to get a similar physique, he only needs to spend two hours a day. However, he still cannot dismiss the fact that even for those two hours, he generates mechanical energy indeed. Totally untapped.

And then I thought about gyms. If a gym is open from morning 6-10 and evening 6-10, it lets people come and generate energy for 8 hours. Can somebody tap it? Anyone wants to reflect on it?

PS: Some dude actually made a small device which you can fit on your shoes and then you can charge batteries when you run. Something similar right?