title: Muscle strength as a determinant of oxygen uptake efficiency and maximal metabolic response in patients with mild-to-moderate COPD.
abstract: OBJECTIVE
  To compare the behavior of the oxygen uptake efficiency slope (OUES) with that of oxygen uptake at peak exertion (VO₂peak).
  
  
  METHODS
  This was a prospective cross-sectional study involving 21 patients (15 men) with mild-to-moderate COPD undergoing spirometry, handgrip strength (HGS) testing, cardiopulmonary exercise testing, and determination of lactate at peak exertion (LACpeak).
  
  
  RESULTS
  Mean weight was 66.7 ± 13.6 kg, and mean age was 60.7 ± 7.8 years. With the exception of FEV₁ and FEV1/FVC ratio (75.8 ± 18.6 of predicted and 56.6 ± 8.8, respectively), all spirometric variables were normal, as was HGS. The patients exhibited significant metabolic and hemodynamic stress, as evidenced by the means (% of predicted) for VO₂peak (93.1 ± 15.4), maximum HR (92.5 ± 10.4), and OUES (99.4 ± 24.4), as well as for the gas exchange rate (1.2 ± 0.1). The correlation between VO₂peak and OUES was significant (r = 0.747; p < 0.0001). The correlation between HGS and VO₂peak (r = 0.734; p < 0.0001) was more significant than was that between HGS and OUES (r = 0.453; p < 0.05). Similar results were found regarding the correlations of VO₂peak and OUES with MIP. Although LACpeak correlated significantly with VO₂peak (r = -0.731; p < 0.0001), only LACpeak/maximum power correlated significantly with OUES (r = -0.605; p = 0.004).
  
  
  CONCLUSIONS
  Our findings suggest that, in mild-to-moderate COPD, VO2 determinants other than overall muscle strength have a greater impact on OUES than on VO₂peak.
authors.affiliation: Federal University of Mato Grosso do Sul School of Medicine, Campo Grande, Brazil. paulo.muller@ufms.br
authors.forename: Paulo de Tarso Guerrero
authors.initials: Pde T
authors.lastname: Müller
authors.forename: Carlos Alberto de Assis
authors.initials: CA
authors.lastname: Viegas
authors.forename: Luiz Armando Pereira
authors.initials: LA
authors.lastname: Patusco
mesh_terms: D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism / Q000503:physiopathology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000502:physiology*; D012720:Severity of Illness Index
chemical_list: D019344:Lactic Acid