Bring your knees as much to the front as possible. Engage your core. You can bring both knees to the front or you can bring your knees towards the elbow of one side to work on your lateral abdominal muscles. Instead of a slider, you can use a blanket, a towel or any other piece of cloth. Great core exercise!
Bring your resistance band under tension behind your shoulders. Arms are stretched to the sides. Bring your straight arms together in front of your chest.