Ab coasters are an effective core exercise using an ab coaster machine. Sit on the seat, grip the handles, and place your knees on the knee pads. Use your core to pull your knees up towards your chest while keeping your upper body stable. Slowly lower your knees back down to the starting position.

1. Sit on the seat, grip the handles, and place your knees on the knee pads.
2. Use your core to pull your knees up towards your chest while keeping your upper body stable.
3. Slowly lower your knees back down to the starting position.