Your sit bones are still on the front of your fit ball when you walk forward. The spine should not collapse into an arch. When you shunt back into the upright position you should remain completely centered on the fit ball and not to bounce.
What does this exercise assist in the ballet class?
This exercise strengthens the upper torso to assist you not to collapse and fall out of any multiple pirouettes.
At what age should I be doing this exercise?
The age suggestion is 14 years and above for this combination, although this depends on the maturity and years of previous training. However this exercise has varied levels of training in all 3 levels of training. Yet some 13 year old students may be clearly strong enough to start training this exercise. However they must be completely competent in the senior level of training before moving forward into the Advanced level