Electromyographic manifestations of fatigue correlate with pulmonary function, 6-minute walk test, and time to exhaustion in COPD

Abstract

BACKGROUND: The aim of this study was to investigate whether electromyographic manifestations of fatigue and exercise tolerance were related to stage of disease in men with a COPD diagnosis. METHODS: Fourteen men with COPD with a diagnosis of mild to severe air flow obstruction were involved in 2 separate testing sessions. The first one consisted of a pulmonary function (FEV1 and FEV1/FVC) and an exercise tolerance assessment using the 6-min walk test. During the second session, a multichannel surface electromyography was recorded from vastus medialis and vastus lateralis muscles during an isometric knee extension at 70% of maximum voluntary contraction. The slope of muscle fiber conduction velocity during the contraction was calculated as the index of fatigue. RESULTS: Conduction velocity slope significantly correlated with FEV1 (vastus medialis: r = 0.86, P