Great lower body work out. Up it a level and do a one legged squat. Raise one foot in a hopping position and rest it behind you on a chair. Squat and touch the ground. I bend forward and touch the ground with my fingers as I do these, so I don't put pressure on my lower back. Try and do 3 sets of 12 on each leg. Your glutes will hurt tomorrow but if you keep it up every second day, you will see results and it won't hurt any more.