Both the muscle force and the weight or load are on the same side for these joints, but they pull in different directions (see Fig. 4-1). The mechanical advantage of these joints is always less than 1. That means that merely to maintain balance, the force supplied by the muscles has to be many times greater than the combined weight of the body parts and the load.
During abduction, the shoulder joint functions as a typical class III lever (Fig. 4-5). The elbow joint can serve as a class I lever for extension and as a class III lever for flexion.
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Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.