The causes of purple dots on the arms of push-ups are divided into physiologic and pathologic. Physiological causes are mainly due to body position, and pathological causes include thrombocytopenic purpura and allergic purpura. 1. Physiological: when doing push-ups, due to the position of the arm blood reflux difficulties, due to gravity causes blood to accumulate in the arm, part of the vascular permeability increases and cause arm congestion with purple dots. When the position is restored, the symptoms will disappear. 2. Thrombocytopenic purpura: Due to the decrease of platelets in blood, the coagulation function is impaired, which can easily cause local bleeding, mainly manifested as petechiae, purpura and ecchymosis of the skin all over the body. It is mainly manifested as generalized skin petechiae, purpura and ecchymosis. 3. Allergic purpura: Typical manifestation is brownish-red rash, protruding from the surface of the skin, and the color does not fade when pressed. In addition to the above causes, food allergy (e.g. seafood allergy) may also cause the above symptoms. It is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment.