What constitutes meaningful gain in skeletal muscle strength in COPD?

Low muscle mass and strength is a common systemic consequence of chronic obstructive pulmonary disease (COPD) and an important determinant of clinical outcomes.1–3 Quadriceps muscle strength, in particular, predicts transplant-free survival in COPD independent of the severity of airflow obstruction.3 While it may be assumed that low muscle strength is an inevitable feature of advanced disease, this is far from reality. Rather, it represents dysfunction of the largest organ system by mass in the human body and is often present in the absence of severe disease.4