Wearing a tight cotton vest will compress the chest. Wearing a tight vest will cause poor blood supply to the breast, which is likely to make the lungs unable to relax and breathe normally, resulting in chest tightness, shortness of breath and difficulty breathing. It may also lead to poor lymphatic reflux in the breast, leading to blood stasis in the breast, ischemia and hypoxia in the breast tissue, failure to discharge excretion products in time, and toxin accumulation affecting the normal development of the breast. People who wear body-shaping underwear will feel chest tightness, shortness of breath and difficulty breathing. Wearing this tight underwear for a long time may also lead to lung function problems or breast compression and deformation, and skin scars.