Exercise method: 1) supine birds. Be careful not to hold your hands too tightly, and tighten your back muscles when you separate your arms, focusing on the contraction and extension of pectoralis major. 2) Flexion and extension of parallel bars. Pay attention to slow down, don't shake your body at will, keep balance, pay attention to the choice of grip distance, the choice of upper body inclination angle, and the angle between upper arm and trunk. 3) Tilt the dumbbell upward and press it. Be careful not to drop too low, so as not to strain your chest muscles. The angle of the inclined plate is controlled between 30 and 45 degrees. 4) Tilt the dumbbell downward and press it. Pay attention to put it on both sides of the lowest rib, not in the middle of pectoralis major, so as not to strain the shoulder joint. 5) butterflies and birds. Be careful not to open your arms too much. 6) Cross-clamp the chest of the puller. Pay attention to using light weight many times.