Use comfort as your guide. You should be able to sit in a comfortable position with hips and knees at approximately 90 degrees. You may slightly inflate or deflate the ball if you feel you are between sizes. Using different sizes of balls will allow you flexibility and variation as you progress with the exercise ball exercises. You may find that one brand of 55 cm ball may be bigger than a 55 cm ball of another brand. Try different sizes of balls for different exercises and be prepared to return a ball you bought because it didn't meet your needs. There are no hard and fast rules. Using different size balls will allow you more flexibility and variation with your exercise ball training. We recommend beginning your program with a softer ball if you've never used an exercise ball before.The firmer the ball, the more difficult you will find it to stabilize yourself on the ball. The more inflated the ball is, the less contact area there is with the floor, the more easily the ball will roll, and the more skill is required to maintain balance on the exercise ball.  |
