Elastic resistance force and torque Elastic resistance is a unique type of resistance training compared to other traditional forms, such as isotonic or isokinetic resistances. The resistance provided by elastic bands or tubing is based on the amount that the band or tubing is stretched. This resistance can be measured in pounds/kilograms of force depending on the percentage the band or tubing is stretched from its resting length; this is known as force-elongation.
Regardless of how long the band or tubing is before it’s stretched, the force produced at its stretched length depends on the percent elongation. For example, an initial 2-foot (60 cm) length of green band that is stretched to 4 feet (120 cm, double its resting length) is at 100% elongation. Therefore, the resistance of the band is 4.6 pounds at that elongation. Each progressive step represents a consistent pull-force increase of 25% in the clinical range (Tan through Black) and 40% in the advanced range (Silver and Gold).
Developed by Juan Carlos Colado, PHD, University of Valencia, Valencia, Spain 1. Colado et al. 2012. J Strength Cond Res. 26 (11):3018-3024 2. Colado et al. 2014. J Sports Sci Med. 13:758