Balancing the Strong Upward Pull of the Deltoid Muscle by Activating the Downward Pull of the Infrapinatus and Teres Minor Rotator Cuff Muscles
Working to avoid excessive motion (off-axis) in the shoulder joint by activating the infraspinatus and teres minor muscle to keep an instant center in the joint. Efforts to develop "boulder shoulders" can damage the rotator cuff -- especially the supraspinatus muscle. The rotator cuff muscles help keep the humerus (upper arm bone) in the the proper place in the glenohumeral joint (shoulder joint). Actions controlling the humerus include abduction (raising the arm), adduction (lowering the arm, think lat pulldown), horizontal adduction (think bench press, chest pulley flys), extension (think close-grip lat pulldown or straight arm triceps pressdown), flexion (think front raise), horizontal abduction (think posterior deltoid machine), external rotation (see video), and internal rotation (deduce opposite of external rotation in video). There are three groups of muscles that provide healthy, pain free, and functional motion of the arms and shoulder when the force tensio...