4. Discussion
muscle dysfunction, COPD
MODERATE CHRONIC OBSTRUCTIVE PULMONARY DISEASE, INFLAMMATION, DISEASE, COPD, OXIDATIVE STRESS, INSULIN SENSITIVITY
This study aimed to examine the effects of eccentric cycling (ECC) and conventional concentric cycling (CONC) training on plasma markers of oxidative stress, systemic inflammation, and cardiometabolic health in patients with moderate chronic obstructive pulmonary disease (COPD). The main findings of this study were: (1) maximal aerobic capacity and time-to-exhaustion (TTE) performance were maintained after 12 weeks of ECC and CONC training; (2) CONC induced an increase in total antioxidant capacity (TAC) and ECC induced a decrease in GPx activity at rest; (3) exercise-induced oxidative stress (i.e., TBARS) showed a smaller increase after CONC training; (4) insulin sensitivity and HDL were improved after CONC training only. Thus, our initial hypothesis was supported as CONC training induced greater improvements in oxidative stress at rest and after exercise, and cardiometabolic health markers changed more favorably after CONC training compared with ECC, while inflammatory markers remained unchanged after both training interventions.We found that neither ECC nor CONC training improved maximal aerobic capacity (VOIncreased serum TBARS levels and reduced GPx activity have been associated with the disease severity of COPD patients [In our study, the TTE test was used to assess endurance capacity, and to induce a standardized (75% of individual POSystemic inflammatory markers were unchanged after ECC and CONC training (We found a 30.8 ± 22.9% decrease in HOMA-IR (Although reductions in circulating lipids have been previously reported after eccentric training [We acknowledge the limitations of our study. First, high variability in the outcome parameters may be due to differences in the severity of the disease of our patients; as we used patients with moderate COPD, this category may be too wide in symptoms and muscle dysfunction degrees, which increased variability. However, a stratified randomization was performed to distribute the participant in order to minimize this effect. Second, a small sample size was also recruited for this study, which also could have affected the variability of the results. Third, although all participants were diagnosed with moderate COPD, different clinical phenotypes exist [