title: Quadriceps wasting and physical inactivity in patients with COPD.
abstract: 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<0.0001) compared with controls but were not significantly different from those with stage I disease. Physical activity level was reduced in stage I (p=0.002) and stage II-IV disease compared with controls. Using regression analysis, physical activity level was independently associated with USRF(CSA) in stage I (p=0.01) but not stage II-IV disease, where residual volume to total lung capacity ratio was the only independent predictor of physical activity level. Quadriceps wasting exists in patients with mild, as well as advanced, COPD, and is independently associated with physical inactivity in GOLD stage I disease. The identification of these patients may guide early lifestyle and therapeutic interventions.
authors.affiliation: NIHR Respiratory Biomedical Research Unit of Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, Fulham Road, SW3 6NP, UK. dinesh.shrikrishna@nhs.net
authors.forename: Dinesh
authors.initials: D
authors.lastname: Shrikrishna
authors.forename: Mehul
authors.initials: M
authors.lastname: Patel
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Tanner
authors.forename: John M
authors.initials: JM
authors.lastname: Seymour
authors.forename: Bronwen A
authors.initials: BA
authors.lastname: Connolly
authors.forename: Zudin A
authors.initials: ZA
authors.lastname: Puthucheary
authors.forename: Simon L F
authors.initials: SL
authors.lastname: Walsh
authors.forename: Susannah A
authors.initials: SA
authors.lastname: Bloch
authors.forename: Paul S
authors.initials: PS
authors.lastname: Sidhu
authors.forename: Nicholas
authors.initials: N
authors.lastname: Hart
authors.forename: Paul R
authors.initials: PR
authors.lastname: Kemp
authors.forename: John
authors.initials: J
authors.lastname: Moxham
authors.forename: Michael I
authors.initials: MI
authors.lastname: Polkey
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Hopkinson
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D018908:Muscle Weakness / Q000000981:diagnostic imaging / Q000209:etiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging; D014463:Ultrasonography