Reuse mechanical power

Hi All,

I am thinking of using mechanical power generated thru various Cardio equipment installed in my fitness center.

There are a lot of cardio equipment such as - Treadmills, cross trainers, cycles in my club. Except the treadmills rest all are manually operated. I am thinking of using this mechanical power in some purpose. It could be converting it to electrical energy - charging a battery bank & using this bank to light up few lights in the club.

Would appreciate if some help can be provided as on how to start as I think there is a lot of scope to it.

Thanks...!!