Inclusion Criteria:  Subjects aged from 40-85 years with the BMI of 18-28kg/m2 are to be enrolled: sample sizes of the norms, heart failure and COPD groups are 10, 20, and 20, respectively, equally distributed in two years. All of the participants had been in a stable clinical condition for at least 1 month before participating in the study. None of the participants had contraindications for cardiopulmonary exercise tests (CPETs).  Exclusion Criteria:  Participants with diabetes mellitus, uncontrolled hypertension, arrhythmia, cancer, liver, renal or autoimmune diseases, or anemia were excluded. However, participants with well controlled diabetes mellitus were included in the HFrEF/HFmrEF group as these conditions often co-exist. Physical activity was not encouraged or limited during the study period.