I'm an expat who's been living in Rio for the past year. I tried out several gyms before joining one and I believe this is the nicest gym in the zona sul (although you pay for it! It's not cheap). They have a wide range of classes and I regularly go to spinning, functional training, and some of the many abs/glutes focused classes. The only one I haven't liked is yoga because I thought it was boring. I also use the pool which is clean - only complaint is it's a little small (2 wide lanes) and the hours for open swim are limited due to classes going on.
Another nice feature is that there are always trainers in the weights areas who you can meet with in the beginning without extra cost to get started on a training plan, and ask advice from anytime about your form or new exercises.
I pre-paid for a year membership since I knew I was staying, but the gym also offers shorter-term options if you're only in Rio for a little while, and they're willing to negotiate on those. read more