**3.2 The Medical Research Council (MRC) dyspnea scale**

Dyspnea perception during daily activities was measured using the MRC dyspnea scale. Modified MRC chronic dyspnea self-administered questionnaire consisting of five questions about perceived breathlessness. Grade 1, "never troubled by breathlessness except on strenuous activity," to Grade 5, "too breathless to leave the house or breathless after undressing ( Bestall et al., 1999; Stenton, 2008).
