An exercise to improve strength and endurance of abdominal muscles. There are many variations, some do more harm than good. Harmful versions include those in which the legs are kept straight, and too much strain is imposed on the neck and lower back. Typically, the subject lies on his or her back, usually with hands on top of the head, knees bent, and soles of the feet flat on the floor about hip-width apart. The subject than curls up, either just lifting the shoulders off the floor or up to a sitting position, touching the elbows to the knees.
Subjects: Sports and Exercise Medicine.