The asymmetry of pectoral muscle is caused by the imbalance of strength, and the imbalance of strength is caused by the asymmetry of action. There are many reasons for asymmetric movements, a large part of which is due to the problem of bone structure, but this can be completely corrected by training.

After many times of self-observation's training, I found that the power on the right side fell more on the shoulder, which led to the reduction of the power directly acting on the right chest. Similarly, as long as your left and right chest muscles are asymmetrical, there must be one side of the strength scattered on other muscles, either the shoulder or the humerus.

What is the reason? It's very simple, and the action is not standardized. The position of the right shoulder is higher than the left shoulder, and the abduction of the right elbow is not as big as that of the left hand. Therefore, every time I feel that the right side is pushing with the shoulder, the feeling of chest muscle congestion is obviously not as strong as that on the left side.