You may have seen them in the gym: half of a large rubber ball
that’s flat on one side. They’re often blue in color and look
like a gigantic outtie belly button. “What are those things?”
you wonder. Well they’re BOSU balls (or balance trainers). It’s
the latest rave to hit fitness centers across America.BOSU is an acronym that stands for "Both Sides Up". You can use
the balls, also referred to as trainers, or balance trainers, on
either side. Whether the rounded bouncy dome part is up or the
fla.