The plank on the BOSU balance trainer is actually easier than the plank
on the floor due to the decreased amount of body weight which needs to be
stabilized. While the uneven surface of the BOSU provides some instability
which may be challenging to some, the BOSU plank is mainly used simply
because the BOSU is handy and other exercises can be easily transitioned
into such as the BOSU dynamic plank.
