The aim of this study was to evaluate the functional capacity and the performance of respiratory and quadriceps muscles in patients with chronic obstructive pulmonary disease (COPD) and relate them to nutritional status and forced expiratory volume in the first second (FEV1). METHODS: Twelve patients with moderate COPD (70±7 years, FEV1 52±17% predicted, body mass index (BMI) 23±4kg/m²) and seven healthy volunteers (69±8 years, FEV1 127±12% predicted, BMI 27±3kg/m²) were evaluated. All of them underwent body composition analysis, measurement of respiratory muscle strength (maximum inspiratory pressure, MIP, and maximum expiratory pressure, MEP), cardiorespiratory exercise test (CET) and evaluation of palm grip strength, peak torque and total work or endurance of the quadriceps femoris. RESULTS: The patients with COPD had lower values for the free-fat mass (FFM) index (18±1 versus 21±1kg/m², p<0.05), maximum load attained in the CET (60±20 versus 102±18 watts, p<0.01), MIP (58±19 versus 87±21cmH2O, p<0.05), palm grip strength (38±6 versus 47±5kg, p<0.05), peak torque (103±21 versus 138±18Nm, p<0.05) and total work of the quadriceps femoris (1570±395 versus 2333±568J, p<0.05) when compared with the control group (independent Student’s t test). There was no correlation between FEV1 and the variables studied, while the FFM correlated with the total work of the quadriceps (Pearson, r=0.6290, p<0.05). CONCLUSIONS: These results indicate that patients with COPD show weakness of the inspiratory and quadriceps muscles and lower functional capacity, when compared with a healthy group. Moreover, they suggest that the degree of airflow obstruction is not a good predictor for quantifying the nutritional and muscle impairments in patients with COPD.
exercise intolerance; muscle performance; functional capacity; COPD
