The present invention relates to determining a neural respiratory drive (NRD) in patients with chronic obstructive pulmonary disease (COPD) based on surface electromyography measurements taken from the intercostal muscles on the chest of a subject (100). An electromyography system is presented that comprises a first electrode (2′) and a second electrode (3′) for contacting a skin of a subject (100), and a recorder (4′) for recording an electromyogram between the first electrode (2′) and the second electrode (3′)； wherein the first electrode (2′) comprises a first electrode area (2A) and a second electrode area (2B) for contacting the skin of the subject (100), wherein the first electrode area (2A) and the second electrode area (2B) are insulated from each other； and the recorder (4′) is configured to form a noise measurement between the first electrode area (2A) and the second electrode area (2B) of the first electrode (2′) for determining a contact quality of an electrode-skin contact of the first electrode (2′). According to further aspects, a corresponding electromyogram recorder (4′) for an electromyography system, a method for electromyogram measurements and a corresponding computer program are presented.
