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Floored me with those Flat Abs Workout : also provides instructions on how to do these exercises correctly... via KAMA FITNESS
Start with your body on the floor in an X. Lift your left hand and bring the weight towards your right shin, lifting your torso and keeping your belly pulled into your spine, until you roll all the way up to balancing on your tailbone. You can come up onto your elbow a bit to make it a little easier—don’t use it as a crutch, but as a guide. Lower back down and alternate sides. Try turning your foot out, still keeping the leg straight, to get a deeper inner thigh workout at the same time.