We did a lot of movements that required leaning over (things like tricep kickbacks, reverse flies, and bosu lifts). I don't know why but these moves really bothered my lower back. It's kind of a shame because I had to pause from some of these moves, even though the muscle it was supposed to target wasn't fatigued. I think my form is pretty solid, so I wonder if it's a sign of a weak core?
While I loved this class because it was HARD, I don't think I like it as much as Body Pump. The instructor was great because he walked around the room the whole time so you felt like you couldn't quit or slack on the moves. The downside to this is often he'd yell out a move and it would take a minute for the class to figure out what movement he was talking about. While most classes include a warm-up and a cool down, this instructor kept us moving and working the entire hour, so you have to include time to do the warm-up and cool down on your own. The kicker for me was that I felt like I was watching the clock throughout the class.
Not my favorite, but definitely a great class to make you work!