For GF the following 5 variables were entered: depression, muscle torque, % predicted FEV1, end SpO2, IL 6; for PF: depression, ISWT, % predicted FEV1 and age; for RA: depression, ISWT, % predicted FEV1 and BMI; for RM: depression, end Borg RPE and end SpO2 and for MF: depression, IL6 and end SpO2. Here, IL6 is linked to major depressive disorder.