1. bench press: mainly practice the thickness of pectoralis major and thoracic groove. Action: put the dumbbell on the bench with both hands, put the dumbbell on the shoulder, and palm up. Push the dumbbell up until the arm is straight, stop for a while, and then slowly recover. Tip: Push-ups and squats are curved, so that pectoralis major can be fully contracted and fully extended. 2. Pushing upwards: mainly practicing upper chest muscles. Action: the action essentials are the same as those recommended for lying position, except that the stool surface is adjusted to an inclined angle of 30 ~ 40 degrees and leans on it. 3. Sleeping bird: mainly practicing the middle thoracic groove. Action: On the supine stool, hold dumbbells with both hands, palms facing each other, and naturally stretch your arms over your chest. The elbow of the arm is slightly bent to lower the dumbbell to the lowest point on both sides, the pectoral muscle is fully extended, and the pectoral muscle is forcibly contracted to lift and restore the arm. 4. supine straight arm pull-ups: expanding the chest and practicing the best action of pectoralis major and serratus anterior. Action: Lie on your back on the cross stool, with your shoulders on the ground and your feet on the ground. Hold one end of the dumbbell on the chest with both hands, and slowly put (put down) the dumbbell on the back of the head with the shoulder as the axis (feel the stretching of the chest muscles and chest). When it reaches the limit, lift the dumbbell to restore it. Note: In order to prevent damage, the descending process should not be too fast.