if you do them on your side you work your outer thigh. if you do it while laying on your back lifting both legs at once then it works your abs and if you do it one leg at a time while laying on your stomach then you're working your butt and lower back... i hope i helped! oh- and i think the ones on the side also help love handles. but those are all different leg lifts. when i do them i do them all around laying differently for a fuller work out.