Is the Bosu a good piece of exercise kit? Well, it depends upon what we do on it. Lying on it, face up or face down is good. Standing on it, flat side up has some benefits. Kneeling on it, or working on it on our hands and knees is fine. But standing on the domed side is not a very good idea. Why? Because of that dome: if we stand on it with both feet, our feet get forced into an outward tilt. Runners tend to learn fairly rapidly to change sides of the road regularly to avoid stressing the ankles when road running, due to the camber in the road. And then we leap willy nilly onto a cambered, wobbly surface and do some squats, or whatever. Not good.
Putting one foot on top, as in the above photo is less daft. Personally, I think there are many much better ways of ankle strengthening than putting them on a bouncy surface and risk straining the ligaments by a violent wobble. And putting one foot, shod in a standard trainer on a bouncy surface is asking for even more trouble, since the deep muscles of the foot have no chance of activating, being encased in high tech cushioning. But maybe Nike knows something about feet that man, being 2 million years old, doesn’t. Certainly Nike’s bean counters do.
There is a place for unstable training in the gym. And a session or two squatting on the flat surface of the Bosu – bouncy bit down – has a place in pre-ski-ing training. But we can never make ourselves strong on an unstable surface. Too much of our energy is going into not falling off the thing. And, funnily enough, we can’t make ourselves stable either.
At best, the Bosu is a good instrument of torture for the abs. It can present a balance challenge if balance is very poor. ((A Swiss ball is better – but standing on a Swiss ball is for the demented since falling off it backwards may kill. Falling off it from a stand in any direction may cause serious damage.)) Various core type exercises can be done on it for variety. Ideally, though, the ‘core’ works throughout any decent exercise session, so additional core work is only a brief part of events and not the main course. And an aerobic class done on a Bosu is just bonkers.