All Bullworker models passed the Bullworker Arnold Classic Challenge... a test of strength only power lifters who could bench press at least 400 lbs could accomplish. Does Model size matters in Isometrics…?  NEVER  When someone claims it does… they are lying about Isometric exercise Isometric  =  Fixed Resistance Isometric exercise is a form of exercise involving the static contraction of a muscle without any visible movement in the angle of the joint; fixed resistance. It should be noted that full muscle extension puts a greater strain on the joints.  Tighter compressions means less strain on your joints. Joints are not muscles… be kind to them. Two images of isometric shoulder exercises:
Both models allow for Isometric exercise. As evidenced by the photos; static muscle contraction is achieved through both models. Once a fixed resistance point of the exercise is established, the muscle is under a fixed load-bearing pressure… all shoulder muscles are under load.
Another example of ARM exercises with a 36 inch Classic and the 20 inch Steel-Bow:   Due to the principles of Isometric Exercises, both bicep muscles are under identical static contraction from different size models... the full size Bow Classic and the compact Steel-Bow. Excellent results are attained with either model... it is the exercise of fixed resistance. Next page: Iso-Motion