Tension of the pectoralis minor muscle itself is not particularly harmful, may be due to the physiological manifestations produced by the movement, generally without treatment, rest can be relieved. However, if the muscle is overly tense for a long time, it is easy to cause myofasciitis, local tendon calcification, and pectoralis minor syndrome. 1. Myofasciitis: when the long-term repeated overstretching of muscles, can cause muscle fiber overload and muscle fatigue, resulting in aseptic inflammatory reaction, clinical manifestations are mainly local muscle pain, pain with activity inconvenience and soreness and weakness. 2. Local tendon calcification: tendon calcification is usually due to local overuse, resulting in chronic non-specific inflammatory reaction of the tendon, abnormal deposition of calcium salts in the tendon, radiographs can be seen in the local presence of streaks of calcium deposition, the main symptom is the local pain in the pectoralis minor muscle. 3. Pectoralis minor syndrome: it refers to the compression symptoms of the neurovascular bundle caused by the prolonged excessive tension of the pectoralis minor muscle. When the brachial plexus nerve is compressed, it can cause pain and numbness in the upper limb, and the symptom can be aggravated by the position of upper limb abduction and so on. When the arteries are compressed, the skin of the upper limbs and hands may be cold, painful and weak. If the pectoralis minor muscle is overly tense for a long time, it may lead to pathological phenomena. It is recommended to relax the muscles of the thoracic area in time and strengthen rest, if not alleviated, it is recommended to consult a professional for help in time.