[Impact that positive reinforcement during spirometry has on the measurement of VC in healthy volunteers].

Objective: Physiologically, VC can vary according to gender, age, body weight and posture, as well as ethnic and anthropometric characteristics. In addition, various diseases can alter VC. In order to measure VC, it is necessary to motivate the patient, to make the instructions understandable, to provide clear information and to have a capable examiner.