Steps of arm shoulder lacing exercise: stand up straight, cross your arms around your shoulders, just like hugging yourself, and then put your shoulders back. Traction muscle group: main muscle groups: trapezius muscle, rhomboid muscle, latissimus dorsi muscle and posterior deltoid muscle. Secondary muscle groups: supraspinatus, infraspinatus, teres major, teres minor. Action tip: Don't hold your chest back. Pull your shoulders back slowly and make a gradual stretch. Which muscle problems are helpful to repair: dislocation, dislocation, acromioclavicular joint separation, sternoclavicular joint separation, shoulder joint compression syndrome, rotator cuff inflammation, scapulohumeral periarthritis, shoulder coagulation (50 shoulders). Which sports are helpful: archery, cricket, baseball, softball, boxing, golf, tennis, badminton, squash, boating, canoeing, swimming and throwing in track and field.