Its more weights than aerobics if its the les mills one, it does get your heart rate up in some of the tracks though. Aww I miss it soooo much role on 6 weeks post op! http://w3.lesmills.com/westcoast/en/classes/bodypump/
ah i didnt do les mills, i hated it lol. did lots of like stepping with weights and squats and tummy stuff. actually tbh i think the stepping was the only aerobic part