Exercises/Jackknife Sit UpJackknife Sit UpEquipmentNoneTarget MuscleWaist(Abdominals, Abs)Similar Exercises to Jackknife Sit UpThese exercises also target the following muscles: WaistAb ScissorsWaistAb WheelWaistBicycle CrunchWaistBicycle Crunch Raised LegsWaistCable Core Palloff PressWaistCable CrunchWaistCable Twist (Down to up)WaistCable Twist (Up to down)WaistCrunchWaistCrunch (Machine)Waist