Hook feet under support and lie supine on floor or mat with hips and knees bent. With both hands, hold plate on chest with forearms crossed or use no weight.
Raise torso from floor by bending waist and hips. Return until back of shoulders contact with floor or mat. Repeat.
If feet are close to hips, bent arms can be lifted above knees, allowing for complete range of motion resulting in a more bell shaped resistance curve (ie: lessened resistance at top of movement) due to more varying force vectors against gravity. The same can be accomplished by placing feet slightly further away from hips, requiring no need to lift arms above knees (as shown).
Exercise can be performed without added weight until more resistance is needed. Exercise can be performed on incline board to increase resistance or decline board to decrease resistance. See Arm Position During Waist Exercises and movement performed with weight behind head. If upper back does not come completely down at end of movement, abdominal muscles may only be isometrically involved in exercise. Pectineus, Adductor Longus, and Brevis do not assist in hip flexion since hips are already initially bent. See Spot Reduction Myth. Also see Dangerous Exercise Essay.