A stability ball is often used to replace a bench for weight training to challenge your balance when doing various exercises. Using the stability ball will improve functional strength and actively engage the muscles of the core when you're performing exercises on it.
Weight training on a stability ball helps enhance balance as well as strength. It gives you more options and can change the intensity of a traditional exercise on the floor. Using a stability ball allows you to work muscles that may have been neglected in standard exercises where there is no demand for balance. Posture is also effected by using the stability ball; as we gain strength and balance, posture is positively effected.
Bench vs. Ball
The same exercises that can be done on a flat bench can also be done on a stability ball. The difference is stability vs. an unstable surface. According to a study done by the Department of Exercise and Sports Science at Ithaca College, when training with a chest press exercise, the stability ball helps improve strength and work capacity. Having this unstable surface fires more muscles in your upper body during resistance training to help you find balance to complete the exercise.
Sitting, Standing, Lying
The stability ball can be used in resistance training to hit all muscles of the body and in all different positions. Sitting on the stability ball to perform an exercise requires the core muscles to be actively engaged as well as those being used in the specific exercise. For example, a lateral raise could be performed sitting on a stability ball to create an unsteady surface. The ball can also be used standing to target the lower body. For a ball squat, place the stability ball between your back and a wall, then you use the wall for support as you lower down into a squat. The ball also can act as a flat bench, and you can lie on it to perform exercises like a chest presses, skull crushers and a even chest fly.
Choosing a Weight
Because of the unstable surface of a stability ball, carefully choose your weight for a given exercise. You will typically use less weight on an unstable surface because your muscles will be more challenged.
Training the Core
The American Council of Exercise says the stability ball is one of the most versatile pieces of exercise equipment because it works the trunk in almost every exercise performed. A standard crunch can be performed on the ball, but with the unstable surface, all muscles of the core will be engaged to maintain form and function. Adding more resistance, like holding a weight on the chest, will make the exercise more challenging.