1. Stretch pectoralis major 15 seconds. Action explanation: the shoulders are raised horizontally and stretched backwards, and the chest muscles have a sense of stretching. Relax and lengthen the shortened chest muscles.

2. Stretch the anterior longitudinal ligament15s. Action explanation: Shoulders are extended backward, palms are opposite, palms are closed, head is tilted back, sternum is raised as high as possible, and breathing is even. When inhaling, you can obviously feel the sternum lifting upwards. Stretch and relax the contracted anterior longitudinal ligament.