Abstract
Background: Pectoralis muscle area (PMA) is a computed tomography-based assessment that can provide insight into clinical features of other skeletal muscles. Respiratory and locomotor muscle dysfunction has been increasingly recognized in patients with interstitial lung disease (ILD). Its contribution to exercise performance has been controversial. We aimed to investigate if PMA is related with respiratory and locomotor skeletal muscle strength in ILD patients, and if skeletal muscle function is reduced and independently related with exercise capacity and dyspnea.
Methods: Cross-sectional study where subjects performed incremental cycling cardiopulmonary exercise testing with maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and quadriceps maximal voluntary contraction (qMVC) before and after exercise.
Results: Thirty ILD patients (forced vital capacity [FVC] and lung diffusing capacity [DLCO] of 60±15% and38±10% of predicted) and 15 healthy controls (C) were studied. Patients presented lower values of MIP and qMVC compared to C. PMA was associated with qMVC only (r= 0.52; p<0.01). Only MEP showed a significant strength decline after exercise, without difference comparing patients and C. In multivariate regression analysis, only FVC remained as independent predictor of peak aerobic capacity and MEP post exercise remained as independent predictor of peak exercise dyspnea.
Conclusion: ILD patients exhibited inspiratory and quadriceps muscle weakness, but PMA was associated with the later only. Muscle weakness was not associated to exercise capacity while expiratory muscle fatigue might underlie exertional dyspnea.
- Copyright ©the authors 2016
