Liability Question

I am an independent contractor personal trainer at a fitness center. I have a contract with them that states I have full control over my business and I agree to pay them 20% of my earnings I make while using their facility. The contract has no exclusive policy, meaning I am free to train where I want.

If I hold a football boot camp program off site (at a park) and charge money and have participants sign my agreement and release of liability am I required to pay the gym 20% of my earnings for participants who are members of the gym?

Also, if a gym member gets hurt, is the gym liable for anything? This is not a gym advertised program and the gym gave me an additional waiver to hold them harmless. What are my legal implications with the gym I train at?

Thank you,
Lara Keyser