Does anyone provide a gym facility for their employees on their premises?

We have acquired some exercise equipment which consists of a couple of treadmills, stair master, bicycle, etc. I have been informed that it would be difficult to implement such a facility due to the risk of personal injury. Disclaimers are not viewed as acceptable. The intention is also for the gym to be used unsupervised, although we would use a trained instructer for inductions, etc.

I would appreciate any advice/suggestions from anyone who already provides this facility on what steps would need to be taken for it to become a staff benefit without any liability to the employer.

Richard