On a daily basis, I see people doing 1 legged squats on things like a Bosu ball. Even worse, doing the same exercise with weights! I always wonder why are they doing this. I am constantly referring to a phrase called "Goal of the Exercise" (GOTE). If I am ever questioned by a client as to why we are "doing this" and I don’t know the answer, then really should we be doing it at all? What's the point of an exercise without a goal? The last time I witnessed squatting on a Bosu, the individual fell off 3 times!! Hardly confidence building. However, each time the person got back up again (under trainer instruction) to fall back off again. The trainer finally gave up and moved on to the "next" exercise. I found this slightly depressing from a professional point of view. Firstly it was obvious the person did not have the ability to squat on a Bosu (this was 2 legged by the way), secondly (and this is only assumption) there is no need to be squatting on a uneven surface and lastly but most importantly, the trainer had no way in her skill set to regress the exercise. In simple terms, it was a "trainer with a new toy syndrome." Okay, maybe thats too judgemental, but it really struck me as much more important to squat on a stable surface first where control could be exhibited rather than on an unstable surface. It also struck me that there was no carry over to the clients day to day life. Evidence exists that specific directions of instability can diminish key muscle contributions. Juris identified that saggital wobble decreases use of plantar flexors during a squat, however many trainers would have you believe that bosu squats would strengthen the aforementioned muscle( s). Roskoff G (MAT specialist to the Denver Broncos) went as far to say "never add instability to instability." It's a recipe for injury! Have you ever noticed what people's ankles are doing when they're squatting on a Bosu? So how could balance be improved?
Start on a stable surface initially and then look for micro progressions. For example, changes in the base of support... if we have control, we could progress maybe from bilateral to single base. Look to use single based support with emphasis on weight bearing on the outside of the foot or the inside of the same foot. You may introduce a flat surface balance board with minimal movement at each end (put a towel underneath for example) or even no movement at one end. If we go to this type of apparatus, we may have to reduce the base of support (between feet distance). We could even progress on a balance board with such variations such as "knees bent" or "knees locked."
Often during progressions of balance, trainers ignore the 3 possible planes of motion. With the right thought patterns, they could work out how to apply force or progressions in each plane. So, what if the person has problems...indeed what are we working on here? Is the problem sensory, is it in the communication or in the muscular response, is the challenge for the person at a specific joint or at the base, or is it in the information gathering and communication part of the exercise?
It must be realized from a trainers point of view that balance is foremost determined by the intersegemental force producing capabilities at each joint in the movement, with the priority starting at the base. You can only progress from can to can’t only as the can increases.
No one starts to bench press crap loads of weight so why do people persist in trying to start improving balance on a bosu or some other uneven surface? Instability plus instability only leads to further instability. Balance can only be improved when control is achieved.