Quadriceps weakness is related to exercise capacity in idiopathic pulmonary fibrosis

Chest. 2005 Jun;127(6):2028-33. doi: 10.1378/chest.127.6.2028.


Study objective: In COPD, it has been shown that peripheral muscle dysfunction is a factor determining exercise intolerance. We examined the hypothesis that exercise capacity of patients with idiopathic pulmonary fibrosis (IPF) is, at least in part, determined by peripheral muscle dysfunction.

Methods: Maximum oxygen uptake (V(O2)max) was evaluated in 41 consecutive patients with IPF, along with potential determinants of exercise capacity, both in the lungs and in the peripheral muscles.

Results: Patients had reduced V(O2)max (893 +/- 314 mL, 46.0% predicted) and reduced quadriceps force (QF) [65% predicted]. Significant correlates of V(O2)max reduction were vital capacity (VC) [r = 0.79], total lung capacity (r = 0.64), diffusion capacity (r = 0.64), QF (r = 0.62), maximum expiratory pressure (r = 0.48), and Pa(O2) at rest (r = 0.33). In stepwise multiple regression analysis, VC and QF were independent predictors of V(O2)max. Furthermore, in subgroup analysis, QF was a significant contributing factor for V(O2)max in patients who discontinued exercise because of dyspnea and/or leg fatigue.

Conclusions: We conclude that QF is a predictor of exercise capacity in IPF. Measures that improve muscle function might improve exercise tolerance.

MeSH terms

  • Aged
  • Cohort Studies
  • Disease Progression
  • Exercise Tolerance / physiology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Muscle Fatigue / physiology*
  • Muscle, Skeletal / physiology*
  • Oxygen Consumption / physiology*
  • Predictive Value of Tests
  • Prognosis
  • Pulmonary Fibrosis / diagnosis*
  • Pulmonary Fibrosis / rehabilitation
  • Regression Analysis
  • Respiratory Function Tests
  • Sensitivity and Specificity
  • Severity of Illness Index