An exercise ball, also known as a yoga ball, is a ball constructed of soft elastic, typically in 5 diameters of 10-centimeter increments, from 35 centimeters to 85 centimeters, and filled with air. The air pressure is changed by removing a valve stem and either filling with air or letting the ball deflate. It is most often used in physical therapy, athletic training and exercise. It can also be used for weight training.
