BRIDGING THE GAP
RESEARCH and PRACTICALITY
The sizes for stability balls are 55 cm., 65 cm., and 75 cm. The common recommendations for a stability ball are a size 55 cm. for individuals below 5'4" tall, a size 65 cm. for individuals 5'5" to 5'11" tall, and a 75 cm. ball for individuals taller than 6'.
My colleagues and I recently submitted a manuscript on research we performed using a stability ball - comparing crunches on a ball versus on the floor - and found greater muscle activity during a crunch motion when the ball was placed below the lumbar curve of your back when compared to a traditional crunch on the floor.
In addition, we found less muscle activity during a crunch when performed with the stability ball was placed at the level of the scapula than in either of the two positions.
Ours, and other's, research proves the stability ball to be truly an effective training device either in the rehabilitation or athletic arena.