Countless ab machines exist to help a person strengthen and tone the abdominal muscles, which surround the stomach. These machines can vary significantly in function and results, not to mention cost. Some ab machines are intended for use exclusively at the gym, since they tend to be quite bulky, heavy, and expensive, while others are designed for use at home. They are designed to be small and compact, as well as lightweight and inexpensive. Simpler equipment such as exercise balls and chin up bars can also be used to strengthen and tone the muscles of the stomach.
Anyone visiting the gym is likely to encounter fairly simple ab machines known as ab benches. These benches are usually situated on an incline, and the user will lie upside-down on the bench. His or her feet will be secured in foot cradles or around a padded bar, which allows him or her to do sit-ups on the bench. The incline is usually adjustable: the flatter the bench, the easier the sit-ups will be, and the steeper the bench, the harder the sit-ups will be. Such ab machines are very effective, but using them can be hard on the back if the person's form is not correct.
Ab balls are large exercise balls that are flexible and inflatable. These ab machines can be used for a variety of different exercises that can target the ab muscles or other muscles of the body. The ball is designed to support the body's weight, and a user can perform exercises while sitting in the ball, lying across it, or supporting only the upper body while the lower body must support itself. Such ab machines are sometimes used in conjunction with dumbbells so the user can enhance the workout with added weight resistance.
Ab twisters are ab machines that force the user to crunch and turn at the same time, thereby strengthening not only the abdominal muscles on the front of the stomach, but also those on the sides of the stomach. The design of such machines can vary significantly, but the general purpose is to cause a twisting motion while still supporting the body's weight. The downside to such machines is the strain that can be placed on the spine; people with lower back issues should generally avoid such machines, as they can lead to slipped discs or other types of discomfort in the back.