SOD1 and chronic obstructive pulmonary disease: SOD1 and catalase expressions were significantly enhanced in healthy myotubes (p = 0.021, p = 0.030, respectively) but not in COPD myotubes after EPS (Figure 6D,H), and the variations in their expression tended to be higher (p = 0.083, p = 0.122, respectively; Figure 6E,I) in healthy myotubes (+68.6%, +60.4%, respectively) compared to COPD myotubes (+19.7%, +12.5%, respectively).