As others have said, every gym has their own policies on that & it’s directly related to their insurance policy. One of the gyms I belong to is a place called Fitness 19 – a smaller chain gym in my neighborhood. I was able to sign my daughter up at age 12 – provided I was with her. I’m not sure at what age she can be in there without me, but I’m not worrying about that for a while! Simply check around – the Y’s are a great place to start. Good luck Sophie.