Progressive angular isometric loading and regressive angular isometric loading, also known as PAILs and RAILs, is a strength training method used to improve joint capacity and mobility. Tissue is held at length passively for at least two minutes, then is isometrically loaded at progressive angles working up to a maximum contraction and held for roughly ten seconds. Then the contraction is reversed, loading the regressive tissue (tissue on the back of the joint), and held maximally for another ten seconds. This method of isometric loading creates space in the joint by allowing access to greater range of motion, which allows us to access new tissue.
Joint function is the prerequisite for all movement. If someone has improper joint function/capacity, their movement patterns will be limited. PAILs and RAILs give the ability to improve joint function by opening up capsular space in the joint, which allows the body access to new tissue.
The Rack Athletic Performance Center