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ATOLLIT

So I've signed up to one of these classes this afternoon at my gym, as I get free classes with the membership I already have and I figured I should start making use of it.

I'm just wondering if anyone has been to one before and could tell me a little bit about how they found it??

I'm also wondering how many calories it is likely to burn - I've just seen a post about working out calories by heart rate but I don't think stopping to take my pulse in the middle of the class is likely to be something I can do! Any ideas?