By holding the body in proper crunch position, the user reduces the risk of injury from improper technique, and gains more from the workout, he said. However, Dahle conceded that the risk of an injury from crunches is not great even without an Ab Roller. Calls to Body by Jake Enterprises, which distributes the Ab Rocker, were not returned. But Francis was dubious about the need for equipment for exercises that require people to only move their abs. Abs work has benefits, said Stuart Rugg, a researcher at Occidental College in Los Angeles, who was not part of Francis's study.
Torso strength helps to support the back and stabilizes the body.
However, Rugg noted that abs work won't rip off the layer of fat in front of the muscles. That has to be done by diet and calorie-burning aerobic exercise, he said. Worse from a point of view of looks, strengthening the stomach muscles without losing the fat may make the stomach seem even bigger, Rugg said. The stronger stomach wall can push out fat that may have previously sagged inward, he said. A person can get strong stomach muscles without buying equipment.