This is a warm-up, rehab and training exercise I always use back, hamstrings and glutes. Mostly you should work with just bodyweight, but sometimes use a little weight like a bar. In this exercise, the position of the back, the amplitude and the tempo of the movement are very important. Your lower back should always be tight, and should never be allowed to completely relax. The downward movement should be slow, while the upward movement should be fast with a 2-3 sec pause at the top. We recommend to finish the movement with your body parallel to the floor!