Joe,

No doubt jumping up and down on concrete for long periods of time could very likely cause damage.  When you and Ray were talking about concrete courts., e.g., you said "I've never seen a concrete basketball court".

I was only trying to point out there were plenty of concrete outdoor courts in inner cities where kids played basketball, wall ball, football, etc. on concrete.  I believe most kids back then playing on concrete did survive without major injuries. 

Would hope the new CC would have an appropiate resilient floor that would lessen long term injury potential for both adults and kids that may use the gym if it is built.

ave Paquet