Plasma metabolic profile in COPD patients: effects of exercise and endurance training

The study examines plasma metabolic profiles of patients with chronic obstructive pulmonary disease (COPD) to prove whether the disease influences metabolism at rest and after endurance training. This is based on the hypothesis that metabolome levels should reflect impaired skeletal muscle bioenergetics in COPD. The study aims to test this hypothesis by evaluating plasma metabolic profiles in COPD patients before and after 8 weeks of endurance exercise training. We studied blood samples from 18 COPD patients and 12 healthy subjects. Pre- and post-training blood plasma samples at rest and after constant-work rate exercise (CWRE) at 70% of pre-training Watts peak were analyzed by 1H-nuclear magnetic resonance spectroscopy to assess metabolite profiles. The two groups presented training-induced physiological changes in the VO2 peak and in blood lactate levels (P < 0.01 each). Before training, the two groups also showed differences in metabolic profiles at rest (P < 0.05). Levels of valine (r = 0.51, P < 0.01), alanine (r = 0.45, P < 0.05) and isoleucine (r = 0.51, P < 0.01) were positively associated with body composition (Fat Free Mass Index). While training showed a significant impact on the metabolic profile in healthy subjects (P < 0.001), with changes in levels of amino acids, creatine, succinate, pyruvate, glucose and lactate (P < 0.05 each), no equivalent training-induced effects were seen in COPD patients in whom only lactate decreased (P < 0.05). This study shows that plasma metabolic profiling contributes to the phenotypic characterization of COPD patients.