title: Prevalence of quadriceps muscle weakness in patients with COPD and its association with disease severity.
abstract: BACKGROUND
  COPD presents with an array of extra-pulmonary symptoms of which skeletal muscle dysfunction, particularly of the quadriceps, is well recognized. This contributes to impaired quality of life and increased health care utilization. Work on the quadriceps originated from the observation that a good proportion of COPD patients stop exercise due to the feeling of leg fatigue rather than breathlessness. This study was carried out with the aim of finding the prevalence of quadriceps weakness in a population set and correlate it with severity of COPD.
  
  
  METHODS
  This cross-sectional study was conducted in 75 subjects suffering from COPD aged 45 years or above. COPD severity in the subjects was graded based on the GOLD staging system. A digital hand held dynamometer (HHD) was used to measure quadriceps muscle strength. Descriptive statistics were done, and Pearson's Correlation Coefficient and ANOVA analysis was used for expressing the results.
  
  
  RESULTS
  Ninety two percent of subjects were suffering from quadriceps muscle weakness. Quadriceps weakness was present in significantly high proportions even in those suffering from mild disease and belonging to a younger age group. The mean quadriceps muscle force value decreased with disease severity and this relation was found to be significant (P<0.01).
  
  
  CONCLUSIONS
  Majority of the COPD patients were found to be suffering from quadriceps weakness, which was also present in significant proportions in subjects belonging to younger age groups and suffering from mild disease. These findings indicate that onset of muscle weakness in COPD may precede the onset of symptoms. These findings suggest need for early remedial measure to prevent occurrence of associated systemic diseases.
authors.affiliation: Kasturba Medical College, Manipal University, Mangaluru, Karnataka, India.
authors.forename: Sidharth
authors.initials: S
authors.lastname: Kharbanda
authors.affiliation: Department of Respiratory Medicine, Kasturba Medical College Hospital, Mangaluru, Karnataka, India.
authors.forename: Anand
authors.initials: A
authors.lastname: Ramakrishna
authors.affiliation: Department of Physiotherapy, Kasturba Medical College Hospital, Mangaluru, Karnataka, India.
authors.forename: Shyam
authors.initials: S
authors.lastname: Krishnan
mesh_terms: D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007194:India / Q000453:epidemiology; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D053581:Muscle Strength Dynamometer; D018908:Muscle Weakness / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D011237:Predictive Value of Tests; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D052097:Quadriceps Muscle / Q000503:physiopathology*; D012307:Risk Factors; D012720:Severity of Illness Index; D013147:Spirometry; D014797:Vital Capacity
keywords: COPD; FEV1; FVC; GOLD staging; Quadriceps muscle strength; hand-held dynamometer; skeletal muscle dysfunction; spirometry