Exercise-Induced Systemic Effects in Muscle-Wasted Patients with COPD

Abstract

Physical exercise is known to induce an acute inflammatory response and oxidative stress in healthy subjects and patients with chronic obstructive pulmonary disease (COPD). Increasing evidence associates systemic inflammation and oxidative stress with muscle wasting and muscle dysfunction in COPD. In the present study, it was hypothesized that exercise-induced systemic inflammatory and oxidative responses in muscle-wasted COPD patients are increased compared with non-muscle-wasted patients and healthy subjects. Pulmonary function, body composition, and quadriceps muscle strength were measured in 10 muscle-wasted (fat-free mass index (FFMI) < 16 kg x m(-2) (men), < 15 kg x m(-2) (women)), 10 non-muscle-wasted COPD patients, and 10 healthy subjects. Systemic inflammation (C-reactive protein (CRP), leukocytes, cytokines) and oxidative stress (production of reactive oxygen species (ROS) by neutrophils, plasma antioxidant capacity, protein oxidation, lipid peroxidation, oxidized to reduced glutathione ratio (GSSG/GSH)) were determined before and after maximal and submaximal (50% of maximal work rate) cycle ergometry. Low-grade systemic inflammation was significantly (P < 0.05) elevated in all COPD patients and tended to be highest in muscle-wasted patients. A decreased antioxidant status (plasma antioxidant capacity, P < 0.05; GSH, P < 0.05) and increased protein oxidation (P < 0.001) reflected increased basal oxidative stress in muscle-wasted COPD patients compared with both other groups. Both maximal and submaximal exercise caused increased inflammatory (IL-6, +1.1 pg. x mL(-1) vs rest, P < 0.05) and oxidative responses (ROS release by neutrophils, + 32%; GSSG/GSH + 29%; lipid peroxidation, + 30% vs rest) in muscle-wasted COPD patients, which were less pronounced or not observed in non-muscle-wasted patients and healthy subjects. These data indicate that both maximal and submaximal exercise induce increased systemic inflammatory and oxidative responses in muscle-wasted COPD patients compared with non-muscle-wasted patients and healthy subjects.