Quadriceps wasting and physical inactivity in patients with COPD

Quadriceps weakness is an important complication of advanced chronic obstructive pulmonary disease (COPD) but few data exist concerning muscle bulk in early disease. We hypothesised that quadriceps bulk, measured by ultrasound rectus femoris cross-sectional area (USRF(CSA)), would be reduced in mild, as well as advanced, COPD compared with controls, and would correlate with physical activity. 161 patients with stable COPD and 40 healthy subjects had a measurement of USRF(CSA) and wore a multisensor armband to record physical activity. USRF(CSA) was reduced in Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I patients compared with healthy subjects (p=0.0002). Stage II-IV patients had reduced USRF(CSA) (p