First of all, as we all know, the pectoral muscles are divided into three parts: upper, middle and lower parts, so when practicing, they are also divided into three parts: flat push, up push and down push. When doing push-ups, when I was practicing in the gym, I observed that the stool was about 45 degrees, and my head leaned against the stool. The stool should not be too wide, not more than the shoulder width, as long as the movement is standardized and the weight is moderate, it will not be injured. There is also the problem of the inner side of the chest muscle, don't forget.