Ab machines are popular tools for training the abdominals, often because they are advertised as being more effective than traditional ab exercises. This, however, is often not the case, as found in a study sponsored by the American Council on Exercise and published in "ACE FitnessMatters." Some machines are poorly constructed and overpriced, as well. Well-made and effective exercises that fit in a home gym do exist, though, if you are discerning in your purchases.
The Ab Works is one of the many ab machines made for supporting the neck and back while doing crunches. The Ab Works machine, however, was the only machine highly recommended by "Popular Mechanics" in an article entitled "Crunch Time: Abdominal Exercise Machines." The Ab Works consists of a back and neck pad that you lie on and a bar to hold onto as you perform crunches. There are other exercises for the abs possible with this machine, but crunches are the most recognized.
The Torso Track is a small, long ab machine that can be easily slid under a bed or tilted against the wall for storing out of the way in a home gym. The Torso Track is significantly better for the abdominal muscles than a traditional floor crunch, according to the ACE-study. This includes the rectus abdominus and oblique muscles, which covers the front and sides of the abdomen. The Torso Track has handles that slide along a track as you hold onto them. Maintaining a flat back and stable torso as you slide the handles from a kneeling position works the abs. This does not require a lot of space.
The Ab Roller is similar to the ab works machines in size. Use of the Ab Roller for ab crunches is slightly more effective than a floor crunch, according to "Ace FitnessMatters." Keep in mind that the original Ab Roller was tested in this study. Newer models such as the Plus and Evolution offer more exercise and weight options, but have a slightly different design.
The Captain's Chair is arguably the best piece of equipment for ab exercises sold today, but it is larger than the other machines. If there is room in a home gym for this machine, it is worth purchasing. The ACE-study ranked the Captain's Chair as the best piece of equipment. The hanging leg raise exercise on this machine was beat only by a non-machine exercise called the bicycle maneuver for most effective ab exercise for the rectus abdominus. This exercise is the best for the obliques, though.