You see them in almost any commercial gym. They sell them at most sporting goods stores. Many large gyms offer group fitness classes with them. In fact, you can even get certified to be a BOSU ball trainer. BOSU balls are the dome-shaped, inflatable, rubber half-balls that have become common fitness tools. Fitness enthusiasts can take any exercise and make it more challenging by performing it on a BOSU ball.
I have seen many pieces of fitness equipment over the years, but the BOSU ball, along with the exercise ball have become staples. It is a fitness tool; piece of equipment that can be used for improving some fitness deficits. It has its place. Training on an unstable surface, like a BOSU ball, has been shown to increase joint stabilizer muscle recruitment. For example, it is a beneficial training tool to enhance ankle stability after you sprain your ankle. However, it also has its limitations and trade-offs. This fact has been overlooked by many gym members and trainers.
Joint stability is important and an adequate level is required for strength training with free weights. This is why stability training is commonly used in the rehab world. After an injury or surgery you are probably going to need to improve joint stability to help restore normal joint function. Once joint stability is adequate, you derive little benefit from training on an unstable surface. In fact, you will limit the benefits of strength training by continuing to train on a BOSU ball.
In a given day you may see many people use the BOSU ball to perform everything from lunges and squats to push-ups and crunches. In fact, you may see trainers encouraging their clients to perform a plethora of these exercises. Sometimes, it is reasoned that performing an exercise while standing on a BOSU ball will help you effectively train your ‘core’ muscles, as you have to work harder to stabilize your body on the unstable surface.
Unfortunately, there is no research (or biomechanical) basis for the claims that performing an exercise like a squat on an unstable surface will enhance your leg or torso strength (core) more so than without it. In fact, just the opposite is true. Research does support the fact that you will actually see inferior results with unstable surface training versus stable surface training in measures of fitness and performance. Why? Well, it comes down to specificity, a very basic strength training principle that states the body will adapt to the kind of demands placed on it. Train on a BOSU ball and it will get a little easier as your body adapts to it. Though, when we measure fitness or performance, it is done on the stable ground. When you train on stable surfaces, you are able to increase the loading of muscles, tendons, ligaments and other joint structures and they adapt to it. When you train on an unstable surface, you are limited by your ability to balance and stabilize your body, so you can’t load the body to the same level as with stable surface training. As they say, “you can’t shoot a cannon from a canoe.” Think about it, can you run faster on an asphalt road or the beach?
So, next time you are at the gym, take a look around. Are people improving their strength or limiting it? There are times when you could enhance a joint’s stability with the appropriate application of a BOSU ball. However, most people (and unfortunately some personal trainers) misuse the BOSU ball because of a misunderstanding of some important strength training principles and misinterpretation of unstable surface training research from physical therapy.