The BOSU isn’t an expletive, although some of my patients do swear when they use it. It is a funny looking piece of equipment: half ball, half platform. You can use one or two at a time, you can use them dome side up or bottom side up, you can put your feet on them, forearms, hands, knees, glutes…
It carries a warning on the bottom: "fall hazard." It’s goal is to stimulate the proprioceptors. What the heck are those? Proprioceptors are found in muscles, tendons and joints. They relay to your brain where you are in space. Yes, you are on planet earth in the Milky Way galaxy but what plane are you in? Is your body up or down, side to side, rotated right or left or a combination of these? The brain responds to this input by telling your body what to do to remain stable so ya don’t fall down!
The proprioceptors can become confused after an illness, injury, or post surgery for example. They then behave a little like your drunk uncle...responding sluggishly. In the therapy world we don’t start with the BOSU right away; it is used in a gradual progression of balance and stability training particularly with athletes.
The BOSU is not just useful for treatment of injury. It is a great tool for injury prevention and performance enhancement as well, especially when used in sport specific ways and always with guidance and instruction from a therapist or personal trainer.