The Bender Ball® is an inflatable plastic ball approximately 9 inches (about 23 cm) in diameter that is the central component of the Bender Method™ of core training developed by fitness instructor Leslee Bender. She has worked in the fitness industry since the 1980s and developed the Bender Ball® as part of a fitness program she refers to as Selective Stabilization™. A Bender Ball® is used in different ways through different workouts, such as placed at the lower back while the user sits up and extends back toward the floor. The purpose of the ball is to allow the user to extend backward beyond his or her starting point as the user does crunches to exercise the abdominal muscles.
A straw is used to inflate the Bender Ball® and the inflation hole is then capped with a plug – both of which are included with the product. The ball is not intended to have weights over 300 pounds (about 136 kg) placed upon it and since it is inflated, it could be prone to bursting from excessive weight. Typically, the ball should not be inflated through the use of a compressor and should be used only on level, non-slippery floors.
By using an exercise ball, a user is able to greatly increase the muscle use necessary for such a workout. Crunches performed from a position of lying flat upon the floor only allow a person to pull him- or herself up into a sitting position, then lie back down on the floor. With something like the Bender Ball® placed at a person’s lower back, he or she is able to lower him- or herself back beyond the user's initial starting point; this requires greater muscular workout from the person’s abdominal region. Making such an exercise part of a person’s core training typically provides a more strenuous workout and usually leads to greater definition of the abdominal region.
The Bender Method™ is a particular set of workouts intended to be used in conjunction with the Bender Ball® and also is created by Leslee Bender; it can be purchased along with the exercise ball to complete the program. Independent research, however, has found that any sort of object about the size of the Bender Ball® that can be comfortably placed under the lower back of someone while he or she does a crunch will allow the user to achieve such increased abdominal exercise. Other products could produce similar results and anyone interested in such products should look into possible alternatives as well.