A large inflatable ball for gym work, also known as physioball or Swiss ball.
Writings – Articles
‘Have a ball!’ by Cathy Pollock on using a gym ball in Alexander Technique lessons, with five different activities.
‘The Alexander Technique and the exercise ball’ by Posie Robins Roth contains activities for using a gym ball in an Alexander Technique class.
Roy Palmer, in his book, Zone Mind, Zone Body, uses an exercise ball for the purpose of staying balanced while sitting on the ball.
Master the Art of Working Out by Malcolm Balk, Andrew Shields contains a section on working with an exercise ball.