Exercise ball balls have been jumped across at 8.31 seconds.The record for the farthest jump between two Swiss balls was also made by Neil at a distance of 2.3 meters in 2012 A primary benefit of exercising with an exercise ball as opposed to exercising directly on a hard flat surface is that the body responds to the instability of the ball to remain balanced, engaging many more muscles. Those muscles become stronger over time to keep balance. Most frequently, the core body muscles — the abdominal muscles and back muscles — are the focus of exercise ball fitness programs. A major
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