Painful symptoms on both sides of the chest muscles, especially on both sides of the pectoralis major muscle, are likely to occur as a result of localized chronic muscle strain. The common triggering factor is excessive local strength training, often fitness people, if the training intensity is too large or incorrect movement, it is likely to lead to local injury, inflammation, inflammation or injury double stimulation, will make the local formation of scar, or even muscle contracture, so that the pain symptoms on both sides of the chest, once this symptom occurs, must not overwork, once overwork will Once this symptom occurs, you must not overexert yourself, as overexertion will induce significant pain. This location also has some lymph nodes in the human body, and when there is an infection in a certain part of the body, there may also be bilateral pain symptoms in the pectoral muscles.