Investigation of oxidative stress, aerobic capacity, daily physical activity and pulmonary functions in patients with mild to moderate COPD

In patients with COPD, by determining the decrease in pulmonary functions and the disease-associated changes in life habits, aerobic exercise capacity, daily physical activity, oxidant and antioxidant status, body composition and health related quality of life changes, the characteristics of patients with COPD may be clarified better. In this study, investigation of total oxidant and antioxidant status, aerobic exercise capacity, daily physical activity, pulmonary functions, body composition, and health related quality of life changes as well as the associations among these parameters was aimed in patients with COPD versus healthy controls.A total of thirty male patients with COPD and thirty healthy male controls were included in this study. Aerobic exercise capacity was determined by Astrand submaximal exercise protocol. Daily physical activity was measured using accelerometer, while pulmonary function tests were measured by portable spirometer. Body composition were determined by using bioelectric impedance analysis system. Skinfold thickness was measured by skinfold caliper, and body circumference measurements were carried out by tape measure. Quality of life questionnaires (SF36 and chronic respiratory disease questionnaires) were applied. Statistical analyses were done using t-test, Mann-Whitney U and Pearson correlation tests of SPSS 16.0 computer program.Aerobic exercise capacity was found to be lower in patients with COPD in comparison to the ones in healthy controls. Aerobic exercise capacity also showed moderate to strong correlations with pulmonary functions. In terms of daily physical activity, no significant differences were found between two groups. The total oxidant value was higher in patients with COPD than the ones in healthy controls, whereas the total antioxidant value was lower in COPD group compared to the control group. Pulmonary function tests showed moderately negative correlations with the total oxidant value, and moderately positive correlations with total antioxidant value in patients with COPD. In addition, there was moderately a negative correlation between total oxidant value and aerobic exercise capacity, while there was moderately a positive correlation between total antioxidant values and aerobic exercise capacity in patients with COPD. Although there was no significant difference among values for age and BMI in both COPD and control groups, values for body fat percentage and waist to hip ratio were found higher in patients with COPD than the ones in healthy controls. Moreover, moderately negative correlations have also been observed between values for waist to hip ratio and pulmonary function tests.In conclusion, despite the fact that higher aerobic exercise capacity in patients with mild to moderate COPD compared to the ones in the healthy controls, unaffected daily physical activity might be attributed to the mild levels of pulmonary dysfunction. It seems that oxidative stress, pulmonary functions and aerobic capacity are interrelated parameters in patients with COPD and we think they might have a role in the pathogenesis of COPD. This study also suggest that abdominal obesity may be considered in the COPD phenotype.