Key points of training: during the practice, the main strength is concentrated on the pectoralis major, so that the pectoralis major is always in a state of tension. Triceps brachii as a secondary supplementary strength. The key exercise parts of lying dumbbell bird: pectoralis major and deltoid muscle. Starting posture: lie on your back on a flat bench, hold dumbbells with both hands, palms facing each other, and push up until your arms are straight and supported on your chest. Action process: two hand-held dumbbells fall to both sides in parallel, with elbows slightly bent, until the muscles on both sides of the chest feel fully stretched, and the upper arm falls below the shoulder level. Take a deep breath when the dumbbell falls. Exhale when holding the bell and lifting it back to its original position. Key points of training: dumbbells fall to both sides. If the arms are straight, it is difficult for the chest muscles to get the feeling of stretching and muscle contraction.