These two movements are beneficial for the spine and lower back. The alligator tail also brings in leg and hip movement. Use some knee padding like a folded towel or blanket to make it nicer for the knees. There are different hand positions depending on wrist comfort. If you don't like kneeling, then don't bother doing these! You could do a seated cat spine roll instead, by sitting comfortably, even on a chair, and rounding your back so you look down, and then arch your back slightly and lift the chin and front ribs.