title: Peripheral muscle weakness contributes to exercise limitation in COPD.
abstract: Recently, it was suggested that fatigue of peripheral muscles could contribute to exercise limitation in patients with chronic obstructive pulmonary disease (COPD). In order to quantify the role of peripheral muscle force, we restudied potential determinants of exercise capacity (6-min walking distance [6 MWD] and maximal oxygen consumption [V02max]) in 41 consecutive COPD patients (FEV1, 43 +/- 19% of predicted, TLCO, 56 +/- 25% of predicted) admitted to our pulmonary rehabilitation program. VO2max (incremental cycle ergometer test), 6 MWD (best of three), lung function (FEV1, FVC, TLC, FRC), diffusing capacity (TLCO), isometric quadriceps force (QF), hand grip force (HF), and maximal inspiratory (PImax) and expiratory (PEmax) pressures were measured. Patients had a poor 6 MWD (372 +/- 136 m) and VO2max (1.35 +/- 0.60 L, 71%), reduced respiratory (PImax 65 +/- 27%) and peripheral muscle force (QF 74 +/- 27%, HF 82 +/- 23%). In single regression analysis, significant correlations (r) were found for VO2max and TLCO (0.68), FEV1 (0.64), QF (0.55), HF (0.53), and body weight (0.49). Walking distance was significantly correlated with QF (0.63), HF (0.61), PImax (0.49), and TLCO (0.38). In stepwise multiple regression analysis, the variables significantly contributing to 6 MWD were QF and Plmax. For VO2max, variables significantly contributing were TLCO, QF, and FEV1. We conclude that lung function and peripheral muscle force are important determinants of exercise capacity in COPD.
authors.affiliation: Respiratory Division, University Hospitals, Katholieke Universiteit Leuven, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Gosselink
authors.forename: T
authors.initials: T
authors.lastname: Troosters
authors.forename: M
authors.initials: M
authors.lastname: Decramer
mesh_terms: D001835:Body Weight; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D005652:Functional Residual Capacity; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018908:Muscle Weakness / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010101:Oxygen Consumption; D005082:Physical Exertion / Q000502:physiology*; D011312:Pressure; D011653:Pulmonary Diffusing Capacity; D012123:Pulmonary Ventilation; D012044:Regression Analysis; D012132:Respiratory Muscles / Q000503:physiopathology; D014109:Total Lung Capacity; D014797:Vital Capacity; D016138:Walking / Q000502:physiology