Exercise ball ball, ball, fitness ball, gym ball, gymnastic ball, physio ball, pilates ball, naval mine, Pezzi ball, stability ball, Swedish ball, therapy ball, or yoga ball. The physical object known as a "Swiss Ball" was developed in 1963 by Aquilino Cosani, an Italian plastics manufacturer. He perfected a process for moulding large puncture-resistant plastic balls. Those balls, then known as "Pezzi balls", were first used in treatment programs for newborns and infants by Mary Quinton, a British physiotherapist working in Switzerland. Later, Dr. Susanne Klein-Vogelbach, the director at the Physical Therapy School in Basel, Switzerland, integrated the use of ball exercise
Elastic and plastic strain Elastic and plastic strain Internal strain within a metal is either elastic or plastic. In the case of elastic strain this is observed as a distortion of the crystal lattice, in the case of plastic strain this is observed by the presence of dislocations –the displacement of part of the crystal lattice. Such strain effects can result in unwanted cracking of the material, as is the case with residual plastic strain. In other cases deliberate introduction of plastic strain results in a strengthening of the material and other performance enhancing behaviors, for example in the manufacture of semi-conductors and solar