Reduced muscle redox capacity after endurance training in patients with chronic obstructive pulmonary disease

The present study was undertaken to test whether endurance training in pati ents with COPD, along with enhancement of muscle bioenergetics, decreases m uscle redox capacity as a result of recurrent episodes of cell hypoxia indu ced by high intensity exercise sessions. Seventeen patients with COPD (FEV1 , 38 +/- 4% pred; Pa-o2, 69 +/- 2.7 mm Hg; Pa-Co2,42 +/- 1.7 mm Hg) and fiv e age-matched control subjects (C) were studied pretraining and posttrainin g. Reduced (GSH) and oxidized (GSSG) glutathione, lipid peroxidation, and g amma-glutamyl cysteine synthase heavy subunit chain mRNA expression (gamma GCS-HS mRNA) were measured in the vastus lateralis. Pretraining redox statu s at rest and after moderate (40% Wpeak) constant-work rate exercise were s imilar between groups. After training (Delta Wpeak, 27 +/- 7% and 37 +/- 18 %, COPD and C, respectively) (p < 0.05 each), GSSG levels increased only in patients with COPD (from 0.7 +/- 0.08 to 1.0 +/- 0.15 nmol/ mg protein, p < 0.05) with maintenance of GSH levels, whereas GSH markedly increased in C (from 4.6 +/- 1.03 to 8.7 +/- 0.41 nmol/ mg protein, p < 0.01). Post-train ing <gamma>GCS-HS mRNA levels increased after submaximal exercise in patien ts with COPD. No evidence of lipid peroxidation was observed. We conclude t hat although endurance training increased muscle redox potential in healthy subjects, patients with COPD showed a reduced ability to adapt to enduranc e training reflected in lower capacity to synthesize GSH.