Need help with how to log "Group Power"

Hey guys. I'm torn between how to log Group Power as I'm not sure if its considered aerobics, high impact or weight training. I've googled it and it comes up with mixed results. I don't have the money for an HRM or a Bodybugg so I'm kind of at the mercy of MFP. I seriously don't think I could burn something as impressive as 600+ calories in one hour and I'm too afraid to "eat it back" if its actually less. I feel like its definitely 400ish but still need help! Thanks a lot!